taxonID	type	description	language	source
03B9420C1D18FFFA1DDBEAF3FEE2FE7B.taxon	diagnosis	Diagnosis. Freshwater Amphiporina lacking intestinal caecum; single pair of intestinal lateral diverticula extending anteriorly from pylorus-intestine junction; hermaphroditic.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D18FFFA1DDBEAF3FEE2FE7B.taxon	discussion	Remarks. The genus Prostoma is herein considered as consisting of two species, P. clepsinoides and P. puteale (see below).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1CFFFA1DDBEDC3FD25FADF.taxon	diagnosis	Diagnosis. An epigean Prostoma; eyes present, usually four or six in number; body usually reddish.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1CFFFA1DDBEDC3FD25FADF.taxon	discussion	Remarks. Until further confirmation by molecular data, all the epigean nominal species are considered junior synonyms of P. clepsinoides (see Discussion below).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1CFFFA1DDBE96FFC43F958.taxon	diagnosis	Diagnosis. A subterranean Prostoma; eyes absent; body white.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1CFFFA1DDBE96FFC43F958.taxon	discussion	Remarks. Pending further confirmation through molecular data, it is proposed herein that P. hercegovinense and P. communopore be considered junior synonyms of P. puteale.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEA4CFD59F843.taxon	description	Source. In the binomen “ Prostoma canadiensis ” [sic] by Gibson & Moore (1978: 80, figs 1 – 6).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEA4CFD59F843.taxon	materials_examined	Type locality. Parry Sound, Georgian Bay, Lake Huron, Canada (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEA4CFD59F843.taxon	etymology	Etymology. Adjective, canadiensis, - is, - e, meaning “ from Canada ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEA4CFD59F843.taxon	discussion	Remarks. With up to 12 proboscis nerves, P. canadiense has been regarded as a valid taxon (Gibson 1995: 494; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62); in the holotype, the proboscis nerves were 10 or 11 in number. Future molecular studies will confirm whether this character state falls within the range of intraspecific variation. Until then, this nominal species should be considered synonymous with P. clepsinoides. See Discussion for the validity of other taxonomic characters.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBE828FBB9F9F0.taxon	description	Source. In the binomen Stichostemma asensoriatum by Montgomery (1896: 436).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBE828FBB9F9F0.taxon	materials_examined	Type locality. A small stream, with the local name of Taylor’s Run, situated about a mile to the north-west of the town of W. Chester, Chester County, Pennsylvania, USA (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBE828FBB9F9F0.taxon	etymology	Etymology. Adjective, asensoriatus, - a, - um; from the negative prefix a -, the Late Latin sensōriUm (“ sensory apparatus ”), and the adjective-forming suffix - ātUs, referring to the supposed absence of the frontal organ.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBE828FBB9F9F0.taxon	discussion	Remarks. The absence the frontal organ, alleged to be specific for S. asensoriatum, is unusual among monostiliferous hoplonemerteans. While a likely explanation for this absence is that it resulted from an artifact during paraffin sectioning, this hypothesis is hardly falsifiable (but see Fig. 3 C, D). Prostoma asensoriatum is listed as a valid name by some authors (e. g., Bürger 1904: 69; Gibson 1995: 493; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62), although it was regarded as invalid by Stiasny-Wijnhoff (1938: 226) and Gibson & Moore (1976: 212). Stichostemma asensoriatum is herein considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEC80FC86FC14.taxon	description	Source. As “ Tetrastemma aquarum dulcium ” [sic] by Silliman (1884: 70, pl. III, figs 19 – 24).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEC80FC86FC14.taxon	materials_examined	Type locality. Monroe County, New York State, USA (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEC80FC86FC14.taxon	etymology	Etymology. Latin feminine noun in the genitive plural, meaning “ of sweet waters ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1DFFFB1DDBEC80FC86FC14.taxon	discussion	Remarks. The monostiliferous hoplonemertean proboscis and the characteristic six eyes depicted in the original illustration of the entire body (Silliman 1884, pl. III, fig. 19), along with its occurrence in a freshwater environment, undoubtedly indicate that the nominal species Tetrastemma aquarumdulcium belongs to Prostoma. Other than “ Tetrastemma aquarum dulcium ”, Silliman (1884) described and re-described 15 species of freshwater turbellarians. Because these 15 were all indicated by binomina, Silliman’s (1884) article can be regarded as consistent with the Principle of Binominal Nomenclature (cf. Article 11.4). It is clear from the description of this taxon placed in Tetrastemma that Silliman (1884) had no intention to establish a new subspecies; besides, there had been no such species as “ Tetrastemma aquarum ”. The two words “ aquarum dulcium ” together refer to “ of sweet waters [of freshwater] ” and thus can be deemed “ a single entity ” in the sense of Article 11.9.5. Therefore, these should be united as aquarumdulcium, rather than the hyphenated form aquarum-dulcium employed by Monticelli (1916: 415) and Corrêa (1964: 549). Volume 41 of Zeitschrift für wissenschaftliche Zoologie contains four issues: the first issue was published on 4 November 1884, the second on 30 December 1884, the third on 17 March 1885, and the fourth on 8 May 1885. Silliman’s article was included in the first issue; thus, the date of publication for Tetrastemma aquarumdulcium is 1884, instead of 1885, as mentioned by later authors (e. g., Bürger 1895: 590; Gibson 1995: 511). Tetrastemma aquarumdulcium has been regarded as synonymous with Prostoma clepsinoides by Bürger (1904: 68) and with Prostoma graecense by Stiasny-Wijnhoff (1938: 226). Gibson & Moore (1976: 197) considered Prostoma aquarumdulcium as a nomen dubium, stating that “ [s] ince the form cannot be clearly distinguished from most of the remaining Prostoma species, the name aquarum dulcium must be invalidated ”. Tetrastemma aquarumdulcium is now once again placed in the synonymy of P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEC80FF14FCC3.taxon	description	Source. In the binomen Prostoma cisalpinum by Vialli (1927: 185).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEC80FF14FCC3.taxon	materials_examined	Type locality. Province of Brescia and Province of Cremona, Lombardy, Italy (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEC80FF14FCC3.taxon	etymology	Etymology. Latin adjective, cisalpīnUs, - a, - um, “ on this [the Roman or south] side of the Alps ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEC80FF14FCC3.taxon	discussion	Remarks. Vialli (1927) considered his P. cisalpinum to most closely resemble P. padanum Pierantoni, 1926 and distinguished the two by the body size (P. cisalpinum being twice the length of P. padanum), the number of eyes (6 in P. cisalpinum; 4 in P. padanum), the position of the cerebral-organ openings; the length of the stylet, and the number of gonads on each side of the body (27 – 28 in P. cisalpinum; 10 in P. padanum). Vialli (1927) also distinguished P. cisalpinum from P. graecense by the absence of tactile bristles at the rhynchodaeal opening and the anus. Vialli (1927) argued that P. cisalpinum is a simultaneous hermaphrodite, while P. eilhaldi was protandrous. Stiasny-Wijnhoff (1938: 226) regarded P. cisalpinum as conspecific with Prostoma eilhardi. Gibson & Moore (1976: 194) considered P. cisalpinum a nomen dubium, and Gibson (1995: 494) listed P. cisalpinum as an invalid name. Prostoma cisalpinum is herein considered synonymous with P. clepsinoides. Volume 65 of Atti della società italiana di scienze naturali e del museo civico di storia naturale in Milano contained four issues. While Issues 1 and 2 were published in 1926, Issues 3 and 4 (which included Vialli’s article) were in 1927. Although later authors regarded the publication date of Vialli’s article, and the name cisalpinum, as 1926 (Stiasny-Wijnhoff 1938: 230; Gibson & Moore 1976: 194; Gibson 1995: 494), the correct publication date is 1927.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEF9CFB69FAF7.taxon	description	Source. In the binomen Prostoma clepsinoides by Dugès (1828: 140, pl. 4, fig. 1, pl. 5, figs 25, 26).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEF9CFB69FAF7.taxon	materials_examined	Type locality. Not explicitly mentioned in the original description; deemed to be Montpellier, France (Fig. 9), by later authors (e. g., Böhmig in Mojsisovics 1893; Joubin 1894; Koroleva et al. 2014).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEF9CFB69FAF7.taxon	etymology	Etymology. Noun, from the glossiphoniid freshwater-leech genus Clepsine Savigny, 1822 and the Latin suffix - oides (“ one that resembles ”). For the publication date of Savigny’s Description de l’Égypte, see Tollitt (1986).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBEF9CFB69FAF7.taxon	discussion	Remarks. The incorrect original spelling of the specific name clepsinoïdes (with ï bearing diaeresis) has been corrected in accordance with Articles 11.2, 27, and 32.5.2. Prostoma clepsinoides has been regarded a nomen dubium by Stiasny-Wijnhoff (1938: 226, as “ P. clepsinoïdes ”) and by Gibson & Moore (1976: 194). Although P. clepsinoides was listed as an invalid name by Gibson (1995: 495), it is now restored as valid.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBE948FD59F88B.taxon	description	Source. In the binomen Prostoma communopore by Senz (1996: 24, figs 1 – 7).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBE948FD59F88B.taxon	materials_examined	Type locality. Ground water among fine sand at a depth of 1.2 m in Kleinzell, “ Kalter Brunnen ”, 40 km southwest of Wien, Austria (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBE948FD59F88B.taxon	etymology	Etymology. Herein regarded as indeclinable according to Article 31.2.3, because its ending is not decisive as to whether it is an adjective or a noun; from the Latin adjective commūnis, “ common ”, and masculine noun porus, “ pore ”, referring to the oesophagus and the rhynchodaeum opening in a common atrium.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D1FFFF91DDBE948FD59F88B.taxon	discussion	Remarks. One of three stygobiont nominal Prostoma species. The common opening of the oesophagus and the rhynchodaeum — considered to be one of the characteristics of this species — can result from the fixation of insufficiently anaesthetized specimens (Fig. 3 A) and, thus, should not be regarded as the normal or natural configuration of these tracts, much less a specie-specific feature for taxonomic purposes. Prostoma communopore has been regarded as a valid taxon by subsequent researchers (Chernyshev et al. 1998: 60; Sundberg & Gibson 2008: 62), but is herein considered synonymous with P. puteale until future studies prove otherwise. See Discussion for the validity of other taxonomic characters.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEC80FC86FD50.taxon	description	Source. In the binomen Polia dugesii by Quatrefages (1849: 210, pl. 13, figs 11 – 13).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEC80FC86FD50.taxon	materials_examined	Type locality. Canal Saint-Martin in Paris, France (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEC80FC86FD50.taxon	etymology	Etymology. A masculine noun in the genitive singular, after Antoine Louis Dugès (1797 – 1838), a French obstetrician and naturalist who discovered and reported freshwater nemerteans for the first time in the history of research.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEC80FC86FD50.taxon	discussion	Remarks. The monostiliferous hoplonemertean proboscis (Quatrefages 1849, pl. 13, fig. 13) and the characteristic six eyes (Quatrefages 1849, pl. 13, fig. 12) depicted in the original illustration, along with its occurrence in a freshwater environment, undoubtedly indicate that the nominal species Polia dugesii belongs to the genus Prostoma. Polia dugesii was transferred to Emea Leidy, 1850 by Leidy (1851: 288). Bürger (1895: 590) placed “ Polia dugèsi ” [sic] in the synonymy of Tetrastemma clepsinoides (Dugès, 1828). Later, Bürger (1904: 68) listed Polia dugesii in the synonymy of Prostoma clepsinoides Dugès, 1828. Prostoma dugesii was regarded as a nomen dubium by Stiasny-Wijnhoff (1938: 224, as “ P. dugèsi ”) and also by Gibson & Moore (1976: 194, as “ dugesi ”). Polia dugesii is now once again placed in the synonymy of P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEEECFD1CFAC8.taxon	description	Source. In the binomen Stichostemma eilhardi by Montgomery (1894: 12).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEEECFD1CFAC8.taxon	materials_examined	Type locality. A water basin in the Berlin Zoological Institute, Berlin, Germany (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEEECFD1CFAC8.taxon	etymology	Etymology. Masculine noun in the genitive singular, after Franz Eilhard Schulze (1840 – 1921), a German anatomist and zoologist and a professor at Friedrich Wilhelm University of Berlin (now Humboldt University of Berlin); Schulze was a supervisor of Thomas Harrison Montgomery Jr. ’ s (1873 – 1912) doctoral thesis.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE61DDBEEECFD1CFAC8.taxon	discussion	Remarks. Stichostemma eilhardi is the type species of Stichostemma Montgomery, 1894 (gender neuter; fixed by monotypy, Article 68.3). It was proposed in Montgomery (1894) and Montgomery (1895), both of which are almost identical in content. Montgomery (1894) was an inaugural dissertation that was publicly defended on 5 December 1894. Montgomery (1895) appeared in Volume 59, Number 1, of Zeitschrift für wissenschaftliche Zoologie, issued on 8 March 1895. The exact publication date is not stated in Montgomery (1894). The name eilhardi may be deemed to have been published on 5 December 1894, according to Article 21.3 (Date incompletely specified). Although P. eilhardi has been regarded as valid by subsequent researchers (Stiasny-Wijnhoff, 1938: 227; Gibson & Moore, 1976: 200; Chernyshev et al. 1998: 61; Gibson 1995: 495; Sundberg & Gibson 2008: 62), it is herein considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE71DDBE994FCA2FEBB.taxon	description	Source. In the binomen Tetrastemma graecensis [sic] by Böhmig in Mojsisovics (1893: LXXXII [82]).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE71DDBE994FCA2FEBB.taxon	materials_examined	Type locality. A waterbody in a botanical garden in Graz, Styria, Austria (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE71DDBE994FCA2FEBB.taxon	etymology	Etymology. Latin adjective, graecensis, - is, - e, meaning “ from Graz ”, while in many other cases it also refers to “ from Greece ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D00FFE71DDBE994FCA2FEBB.taxon	discussion	Remarks. The species name “ Tetrastemma graecensis ” was proposed during a presentation by Ludwig Böhmig at a meeting of the zoology section of the Naturwissenschaftlicher Verein für Steiermark [Natural-Science Association of Styria] on 17 December 1892. The contents of Böhmig’s talk were included in a report by Mojsisovics (1893: LXXXII – LXXXIX [82 – 89]). The author of the name graecensis (graecense) is therefore Böhmig, rather than Mojsisovics, according to Article 50.2. Strict adherence to Recommendation 51 E would be that the author of graecense be cited as ‘ Böhmig in Mojsisovics, 1893 ’. In the present paper, however, it is simplified as ‘ Böhmig, 1893 ’. Mojsisovics’ article appeared in Volume 29 of the Mittheilungen des naturwissenschaftlichen Vereines für Steiermark, which contained various reports of the Verein ’ s activity in 1892 (Jahrgang 1892, ‘ business year 1892 ’). While “ Jahrgang 1892 ” is printed on the title page of the volume, the actual publication year, 1893, is also printed on the same title page. The publication date of the name graecensis is thus 1893, although it has long been erroneously ascribed to 1892 in all subsequent literature to the best of my knowledge (e. g., Bürger 1895: 590; Bürger 1904: 69; Gibson & Moore 1976: 200; Gibson 1995: 516; Chernyshev et al. 1998: 61; Kajihara 2007: 311).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBEF9DFD63FAF7.taxon	description	Source. In the binomen Prostoma hercegovinense by Tarman (1961: 183).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBEF9DFD63FAF7.taxon	materials_examined	Type locality. Two caves in Bosnia and Herzegovina; one near Zavala in Vjetrenica, the other in Bileća (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBEF9DFD63FAF7.taxon	etymology	Etymology. Adjective, hercegovinensis, - is, - e, meaning “ from Hercegovina ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBEF9DFD63FAF7.taxon	discussion	Remarks. Prostoma hercegovinense, one of three stygobiont nominal species in the genus, has been regarded as a valid taxon by subsequent researchers (Gibson 1995: 495; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62). Chernyshev et al. (1998: 62) noted that distinguishing P. hercegovinense from P. puteale Beauchamp, 1932 would be difficult due to the simple original description of the former. It is herein considered synonymous with P. puteale until future studies prove otherwise.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBE949FD8CF8D3.taxon	description	Source. In the binomen Prostoma jenningsi by Gibson & Young (1971: 122, text-fig. 1, pl. 1, figs a – d).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBE949FD8CF8D3.taxon	materials_examined	Type locality. Marginal vegetation and among mud between plant roots and basal leaves in a pond near Croston, Lancashire, England (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBE949FD8CF8D3.taxon	etymology	Etymology. Masculine noun in the genitive singular; after Joseph B. Jennings at the University of Leeds, a former teacher of the first author, Raymond Gibson, “ to mark his contributions to the field of invertebrate digestive physiology ” (Gibson & Young 1971: 122).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBE949FD8CF8D3.taxon	discussion	Remarks. Prostoma jenningsi has been regarded as a valid taxon by subsequent researchers (Gibson & Moore 1976: 203; Gibson 1995: 496; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62). However, an extensive survey of the type locality and its vicinity failed to find any individuals genetically distinct from other worldwide forms, suggesting that P. jenningsi would be a junior synonym of older-established species (Quigg et al. 2020). It is now synonymised with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBED85FB02FCC3.taxon	description	Source. In the binomen Stichostemma grandis [sic] by Ikeda (1913: 240, text-figs 1 – 2, pl. IV, figs 1 – 5).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBED85FB02FCC3.taxon	materials_examined	Type locality. A botanical garden in the Hiroshima Normal School (now Hiroshima University), Hiroshima, Japan (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBED85FB02FCC3.taxon	etymology	Etymology. Latin adjective, grandis, - is, - e, meaning “ large ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE71DDBED85FB02FCC3.taxon	discussion	Remarks. Ikeda (1913: 248) compared Prostoma grande with P. graecense, P. eilhardi, and P. asensoriatum in terms of nine characters (maximum body length, body colour, presence / absence of frontal organ, presence / absence of sensory spines, number of eyes, number of proboscis nerves, degree of posterior extension of cephalic glands, number of gonads, and mode of hermaphroditism [simultaneous / protandrous]). Prostoma grande was regarded as a valid taxon by Stiasny-Wijnhoff (1938: 226), but as a nomen dubium by Gibson & Moore (1976: 195) and listed as an invalid name by Gibson (1995: 495). It is now considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE41DDBEB6DFAE5FEE7.taxon	description	Source. In the binomen Prostoma kolasai by Gibson & Moore (1976: 204, figs 2, 3). Type locality. Konin Lakes, Konin, Poznań, Poland (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D01FFE41DDBEB6DFAE5FEE7.taxon	etymology	Etymology. Masculine noun in the genitive singular; after Jerzy Kolasa, the original finder of the species. Remarks. Although the species has been regarded as a valid taxon by subsequent researchers (Gibson 1995: 496; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62), it is herein considered synonymous with P. clepsinoides. For the overlooked presence of the frontal organ (Fig. 6 A – L) in the original description, see Discussion.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBEF9DFEEAFA83.taxon	description	Source. In the binomen Prostoma lombricoideum by Dugès (1830: 74, pl. 2, fig. 2).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBEF9DFEEAFA83.taxon	materials_examined	Type locality. Not explicitly mentioned in the original description; deemed to be Montpellier, France (Fig. 9), by later authors (e. g., Böhmig in Mojsisovics 1893; Joubin 1894).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBEF9DFEEAFA83.taxon	etymology	Etymology. Adjective, lombricoideus, - a, - um; from the Latin masculine noun lUmbrīcUs (genitive lUmbrīcī) and the Latin suffix - oideus (“ resembling ”).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBEF9DFEEAFA83.taxon	discussion	Remarks. The nemertean attribution of P. lombricoideum may be supported by documentation of the proboscis observed in this species (Dugès 1830), although it lacks any definitive illustration. Frequent incorrect spellings include lumbricoideum (e. g., Hallez 1910 a, b; Monticelli 1916; Vialli 1927) and lumbricoides (e. g., Bürger 1895: 591; Böhmig in Mojsisovics 1893: 479). Prostoma lombricoideum was regarded as a valid name by Stiasny-Wijnhoff (1938: 226, as “ P. lumbricoïdeum ”) but as a nomen dubium by Gibson & Moore (1976: 194, as “ lumbricoideum ”). Gibson (1995: 496) listed Prostoma lombricoideum as an invalid name. It is herein considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBE9DDFD1BF843.taxon	description	Source. In the trinomen Prostoma eilhardi macradenum by Sun & Yin (1995: 135, figs 1 – 3).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBE9DDFD1BF843.taxon	materials_examined	Type locality. A pond called Xiaoxihu (meaning “ small west lake ”) in Zhongshan Park, Qingdao, China (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBE9DDFD1BF843.taxon	etymology	Etymology. Adjective, macradenus, - a, - um; from Ancient Greek µ ᾰκρός (makros, “ large ”), ᾰ ̓ δήν (ad ḗn, “ gland ”), and the Latin adjective forming suffix - us, referring to the large cephalic gland.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBE9DDFD1BF843.taxon	discussion	Remarks. Sun & Yin (1995) noted that Prostoma eilhardi macradenum was similar to Prostoma graecense and Prostoma jenningsi, but could be distinguished by its indistinct and unciliated oesophagus, the rhynchodaeum without longitudinal musculature, and the proboscis with 9 – 10 nerves. Compared to the nominotypical P. e. eilhardi, the new subspecies was thought to be differentiated by its voluminous cephalic glands extending posteriorly behind the dorsal cerebral commissure. Elevated to the species rank by Chernyshev et al. (1998: 61), but it was listed as a subspecies in Sundberg & Gibson (2008) and Strand & Sundberg (2015). It is herein considered synonymous with P. clepsinoides until future studies prove otherwise.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBED79FC0EFCC3.taxon	description	Source. In the binomen Tetrastemma lacustre by Du Plessis (1892: 66).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBED79FC0EFCC3.taxon	materials_examined	Type locality. Lake Geneva in Anières, Geneva, Switzerland (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBED79FC0EFCC3.taxon	etymology	Etymology. Latin adjective, lacustris, - is, - e, meaning “ of lake ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D02FFE41DDBED79FC0EFCC3.taxon	discussion	Remarks. Redescribed as Emea lacustris by Du Plessis (1893: 329 – 357, pl. XII, figs 1 – 3). Tetrastemma lacustre Du Plessis, 1892 was regarded as synonymous with Prostoma lombricoideum Dugès, 1830 by Stiasny-Wijnhoff (1938: 225). Gibson & Moore (1976: 195) suggested that Tetrastemma lacustre might be synonymous with Tetrastemma graecense. Prostoma lacustre is listed as an invalid name by Gibson (1995: 496), but herein considered synonymous with P. clepsinoides. Volume 15, Number 381 of Zoologischer Anzeiger, in which Du Plessis’ (1892) article was included, was issued on 11 January 1892. The name lacustre Du Plessis, 1892 thus takes precedence over graecense Böhmig, 1893, the publication date of the latter has long been erroneously regarded as 1892.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEC80FD35FDC4.taxon	description	Source. In the binomen Koinoporus mapochi by Sanchez & Moretto (1988: 195).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEC80FD35FDC4.taxon	materials_examined	Type locality. Mapocho River, Talagante, central Chile (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEC80FD35FDC4.taxon	etymology	Etymology. A masculine noun in the genitive singular, meaning “ of the Mapocho River ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEC80FD35FDC4.taxon	discussion	Remarks. Koinoporus mapochi is the type species of Koinoporus Sanchez & Moretto, 1988 (gender masculine), fixed by original designation (Article 68.2). Koinoporus was considered distinctive from Prostoma mainly by the following three characteristics: i) the rhynchodaeum and the oesophagus open into a common atrium; ii) the stomach and the anterior intestine possess helicoidal somatic musculature; and iii) being ovoviviparous. The taxonomic validity of these characters is evaluated in the Discussion below. Koinoporus mapochi is herein considered synonymous with P. clepsinoides; thus, Koinoporus is a junior synonym of Prostoma; previously, the name mapochi has not been combined with Prostoma.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEE98FAF9FAAC.taxon	description	Source. In the binomen Prostoma ohmiense by Chernyshev et al. (1998: 53).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEE98FAF9FAAC.taxon	materials_examined	Type locality. Off Shin-asahi-chō, Lake Biwa, Shiga Prefecture, Japan (Figs 1, 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEE98FAF9FAAC.taxon	etymology	Etymology. Adjective, ohmiensis, - is, - e, meaning “ from Ohmi ”; Ohmi is an old Japanese place name referring to the district around Lake Biwa.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBEE98FAF9FAAC.taxon	discussion	Remarks. Prostoma ohmiense was listed as a valid taxon by Sundberg & Gibson (2008: 62). It was described based on specimens from Lake Biwa and was reportedly differentiated from other congeners by the following characteristics: i) four or six pairs of eyes, ii) a rhynchodaeal wall with thin longitudinal muscles, iii) a proboscis with nine nerves, iv) oesophageal epithelium largely devoid of cilia, with sparse cilia present ventrally, v) an indistinct pylorus, and vi) cephalic glands extending back to the brain and opening externally via the frontal organ. However, each individual character state was found in at least one of the nine specimens examined in this study. For example, character i) was observed in ICHUM 6278; ii), vi), v), vi) were observed in ICHUM 6272; and iii) was observed in ICHUM 6277. This pattern can be interpreted as evidence that these traditionally used morphological characters vary either intraspecifically or randomly during histological preparation (e. g., protrusion of the oesophagus or stomach during fixation), rendering them unreliable for species-level discrimination. Indeed, previous studies have reported that differences in such internal characters may either be masked by contraction artifacts during fixation or fall within the range of intraspecific variation in some marine monostiliferans (Sundberg 1979, 1980; Norenburg 1986; Envall & Sundberg 1993). The present material from the type locality now suggests that this nominal species belongs to the cosmopolitan epigean Prostoma, to which the name P. clepsinoides is applied in this paper.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBE9B0FD1CF824.taxon	description	Source. Pierantoni (1926: 436) noted “ Prostoma padanum ” and “ P. padanum sp. nov. ”, but in a taxonomic heading on another page “ Prostoma (Stichostemma) padanus ” [sic] (Pierantoni 1926: 440).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBE9B0FD1CF824.taxon	materials_examined	Type locality. A slow water flow near the west bank of the River Po in the district Millefonti, Turin, Italy (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBE9B0FD1CF824.taxon	etymology	Etymology. Adjective, padanus, - a, - um, from Padus (the River Po) and the suffix - ānUs, meaning “ of the River Po ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D03FFE51DDBE9B0FD1CF824.taxon	discussion	Remarks. Pierantoni (1926) characterized P. padanum as small in size (8 mm long, 0.5 mm wide), with a head tapering anteriorly, almost conical, and a reddish flesh colour near the cephalic region; lacking tactile bristles on both ends of the body; possessing a frontal organ; with the rhynchodaeum opening together with the oesophagus; the rhynchocoel extending posteriorly for 2 / 3 of the body length; the proboscis anterior chamber the same width as posterior chamber, and twice as long as the latter; and being simultaneous hermaphrodite, with external and probably cross fertilization. Prostoma padanum was regarded as a valid taxon by Stiasny-Wijnhoff (1938: 227), but as a nomen dubium by Gibson & Moore (1976: 194). It was listed as an invalid name by Gibson (1995: 497), but herein considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE31DDBE9F8FC30FF03.taxon	description	Source. In the binomen Emea rubra by Leidy (1850: 125).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE31DDBE9F8FC30FF03.taxon	materials_examined	Type locality. Philadelphia, USA (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE31DDBE9F8FC30FF03.taxon	etymology	Etymology. Latin adjective, ruber, rubra, rubrum, meaning “ red ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE31DDBE9F8FC30FF03.taxon	discussion	Remarks. Leidy’s (1850: 125) original description of the ‘ alimentary canal’ — “ intestine cylindrical, narrowed posteriorly, furnished with a small, round, muscular stomach, containing a corneous dental apparatus at its entrance ” — does not seem to apply to a monostiliferous hoplonemertean. However, another sentence in Leidy’s (1851: 288) redescription, “ [oe] sophagus very long and tortuous, villous, furnished at its bottom with a single spine or nail-like tooth, and four others upon each side in a rudimentary condition, enclosed in a sac ”, strongly suggests that the proboscis anterior and middle chambers were mistaken as the oesophagus and the stomach, respectively. If this is correct, the taxon’s monostilifrous hoplonemertean identity is almost unquestionable; the yellowish fleshcoloured body with two or three pairs of eyes is indicative of Prostoma affiliation. Emea rubra is the type species of Emea Leidy, 1850 (gender feminine), fixed by monotypy (Article 68.3). The genus Emea was listed as synonymous with Prostoma by Bürger (1904: 53). Prostoma rubrum was regarded as a nomen dubium by Stiasny-Wijnhoff (1938: 224, as “ P. rubra ”) and by Gibson & Moore (1976: 196). Prostoma rubrum is listed as an invalid name in Gibson (1995: 498), but herein considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEC80FE80FD08.taxon	description	Source. In the binomen Limnemertes poyangensis by Gibson & Wang (2002: 186).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEC80FE80FD08.taxon	materials_examined	Type locality. Poyang Lake, People’s Republic of China, in the northern Jiangxi Province at the junction between the middle and lower reaches of Changjiang (Yangtze) River, 28 ° 25 ' – 29 ° 45 ' N, 115 ° 48 ' – 116 ° 44 ' E (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEC80FE80FD08.taxon	etymology	Etymology. Adjective, poyangensis, - is, - e, meaning “ from Poyang ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEC80FE80FD08.taxon	discussion	Remarks. Limnemertes poyangensis is the type species of Limnemertes Gibson & Wang, 2002 (gender feminine), fixed by original designation (Article 68.2). Gibson & Wang (2002) differentiated Limnemertes from Prostoma mainly by i) being gonochoristic (whereas Prosoma is hermaphroditic), ii) having a short rhynchocoel, less than half the body length (whereas it extends to approximately two-thirds in adult Prostoma), and iii) the anteriorly divided body-wall longitudinal musculature. The first character is not convincing because the original description of L. poyangensis does not include any photomicrographs of the reproductive system. The second character is dubious because the measurement was conducted on fixed specimens cleared in xylene (ibid., p. 191) rather than on living state or sectioned material, and it may therefore be inaccurate. For the third character, see Discussion. Limnemertes poyangensis is herein considered synonymous with P. clepsinoides until future studies prove otherwise; thus, Limnemertes is a junior synonym of Prostoma; the name poyangensis has not been combined with Prostoma.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEF54FCEDFA67.taxon	description	Source. As a variety, Prostoma clepsinoides var. putealis [sic] by Beauchamp (1932: 269, fig. 1).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEF54FCEDFA67.taxon	materials_examined	Type locality. A well in Illkirch-Graffenstaden, France, in the ground water layer of the alluvium of the Rhine near Strasbourg (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEF54FCEDFA67.taxon	etymology	Etymology. Adjective, pUteālis, - is, - e, meaning “ pertaining to well ”; from the masculine noun, puteus, “ pit, dungeon; well; cistern ”, and the suffix - ālis, forming adjective of relationship from nouns or numerals.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D04FFE21DDBEF54FCEDFA67.taxon	discussion	Remarks. One of three stygobiontic nominal Prostoma species. Beauchamp (1932) considered this eyeless form a variety of P. clepsinoides Dugès, 1828. Before 1985, however, subsequent researchers (e. g., Stiasny-Wijnhoff 1938: 225; Gibson & Moore 1976: 198) regarded the taxon as a distinct species due to its remarkable characteristics (e. g., pure white body colour, without eyes) compared with other epigean species (mostly reddish body, with four to six eyes), and referred to it as Prostoma puteale. The name puteale is thus an available species-group name in accordance with Article 45.6.4.1, which states, “ a name that is infrasubspecific under Article 45.6.4 is nevertheless deemed to be subspecific from its original publication if, before 1985, it was either adopted as the valid name of a species or subspecies or was treated as a senior homonym ”. Prostoma puteale has been regarded as a valid taxon by subsequent researchers (e. g., Stiasny-Wijnhoff 1938: 226; Gibson & Moore 1976: 198; Gibson 1995: 497; Chernyshev et al. 1998: 61; Sundberg & Gibson 2008: 62).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBE9B1FCCEF86F.taxon	description	Source. As “ p. biancastro ” [sic] in Delle Chiaje (1841: 111).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBE9B1FCCEF86F.taxon	materials_examined	Type locality. Sicily, Italy.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBE9B1FCCEF86F.taxon	etymology	Etymology. Italian adjective, biancastro, meaning “ whitish ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBE9B1FCCEF86F.taxon	discussion	Remarks. Dugès (1830: 74) identified a four-eyed species found under stones in the rocky intertidal zone of the Mediterranean as Prostoma candidum (Müller, 1774). The specimen was fusiform, 22 mm in length, yellowish and mottled with white, with a brown line extending from the anterior to the posterior. Later, Delle Chiaje (1841: 111) observed a form with four eyes and a greenish-yellow body in Sicily, which he tentatively identified as Prostoma candidum of Dugès (1830). In a taxonomic heading, Delle Chiaje (1841: 111) referred to it as “ P. candidum? (p. biancastro) DUG. ” Bürger (1904: 64) included Delle Chiaje’s (1841) “ P. biancastro ” in the synonymy of Prostoma candidum (Müller, 1774). “ Prostoma biancestro Delle Chiaje, 1841 ” [sic] is listed as if it were an available (but invalid) name by Gibson (1995: 494). However, it is evident from Delle Chiaje’s (1841) text that “ biancastro ” was an Italian vernacular name rather than a scientific name.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBED5DFBADFD53.taxon	description	Source. In the binomen Prostoma sebethis by Monticelli (1910 a: 33).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBED5DFBADFD53.taxon	materials_examined	Type locality. Sebeto, a small river running in Naples, Italy (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBED5DFBADFD53.taxon	etymology	Etymology. A feminine noun in the nominative / genitive singular (both cases have the same ending); Sebethis is a nymph, daughter of the river and god Sebethus, near Naples (Mandelbaum 1981: 400).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBED5DFBADFD53.taxon	discussion	Remarks. Also mentioned as a new species in Monticelli (1910 b: 367) and described in more detail in Monticelli (1916: 401 – 417, pl. 16, figs 1 – 8), which, however, was based on a single, immature specimen. Stiasny-Wijnhoff (1938: 222) and Gibson & Moore (1976: 194) regarded Prostoma sebethis as a nomen dubium, and Gibson (1995: 498) listed it as an invalid name. It is now considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBEEEDFC60FB5B.taxon	description	Source. In the binomen Tetrastemma turanicum by Fedchenko (1872: 101, pl. XIV, figs 1 – 4).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBEEEDFC60FB5B.taxon	materials_examined	Type locality. Tashkent, Uzbekistan (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBEEEDFC60FB5B.taxon	etymology	Etymology. Adjective, - us, - a, - um; from Turan (a region in Central Asia, originally populated by Iranian Central Asian nomads; later, Iranians came to identify Turkic neighbours as Turanians) and the attributive adjective forming suffix - icus.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D05FFE31DDBEEEDFC60FB5B.taxon	discussion	Remarks. The monostiliferous hoplonemertean proboscis and the characteristic six eyes depicted in the original illustration of the entire body (Fedchenko 1872, pl. XIV, fig. 1), along with its occurrence in a freshwater environment, undoubtedly indicate that the nominal species Tetrastemma turanicum belongs to Prostoma. Prostoma turanicum was regarded as a nomen dubium by Gibson & Moore (1976: 194), listed as an invalid name by Gibson (1995: 498), and is now considered synonymous with P. clepsinoides.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEF54FF18FB10.taxon	description	Source. Published in the binomen “ Emea Sillimani, Grd. ” [sic] by Girard (1893: 242).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEF54FF18FB10.taxon	materials_examined	Type locality. Monroe County, New York State, USA (same for Tetrastemma aquarumdulcium Silliman, 1884) (Fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEF54FF18FB10.taxon	etymology	Etymology. A masculine noun in the genitive singular, after Wyllis A. Silliman, who described Tetrastemma aquarumdulcium.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEF54FF18FB10.taxon	discussion	Remarks. Girard (1893: 242) transferred Tetrastemma aquarumdulcium Silliman, 1884 to Emea, renaming it Emea sillimani and attributing himself as the naming authority in a taxonomic heading. This was accompanied by the synonymy: “ SYN. — Tetrastemma aquarum dulcium, Sillim. Zeits. wiss. Zool., XLI, 1885, p. 70, pl. III, 19 – 24. ” Emea sillimani is unavailable under Article 11.6, although Gibson (1995: 362) listed it as an invalid (but available) name.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEC80FABCFD08.taxon	description	Source. As “ hokkaidoensis ” (Stiasny-Wijnhoff 1938: 222) and “ P. hokkaidoensis ” (Stiasny-Wijnhoff 1938: 224).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEC80FABCFD08.taxon	materials_examined	Type locality. Sapporo, Hokkaido, Japan.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEC80FABCFD08.taxon	etymology	Etymology. Adjective, - is, - is, - e; “ from Hokkaido ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D06FFE01DDBEC80FABCFD08.taxon	discussion	Remarks. Stiasny-Wijnhoff (1938) mistakingly interpreted Ishizuka (1933) as having established a taxon named Prostoma hokkaidoense. In reality, Ishizuka (1933: 218) stated only that “ the nemertean of Sapporo [in Hokkaido] is probably referable to the European species, P. graecense ”, without mentioning any name such as hokkaidoensis or hokkaidoense. The name Prostoma hokkaidoense might have been deemed established by Stiasny-Wijnhoff (1938) via bibliographic reference (Article 13.1.2) to Ishizuka (1933). However, Stiasny-Wijnhoff (1938) recognized only six valid species (P. lombricoideum, P. puteale, P. grande, P. padanum, P. graecense, and P. eilhardi), and Prostoma hokkaidoense was not treated as a valid taxon. Therefore, Prostoma hokkaidoense is unavailable under Article 11.5, which requires names to be used as valid when proposed. Nonetheless, Gibson (1995: 496) listed “ Prostoma hokkaidoensis Stiasny-Wijnhoff, 1938 ” as if it were an available name, and Crandall et al. (2002: 14, 21, 29, 43) included “ Prostoma hokkaidoense Stiasny-Wijnhoff, 1938 ” as a valid name. Gibson & Moore (1976: 194), addressing Stiasny-Wijnhoff’s (1938) misconception, correctly noted that “ hokkaidoense is clearly not taxonomically allowable ”. However, the issue pertains to nomenclatural status rather than taxonomy.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0AFFED1DDBEB24FDFDFF2F.taxon	description	Source. In the binomen Prostoma albolineatum by Timofeev (1911: 37, fig. 6).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0AFFED1DDBEB24FDFDFF2F.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0AFFED1DDBEB24FDFDFF2F.taxon	etymology	Etymology. Adjective, albolīneātUs, - a, - um; from Latin albus, “ white ”, and līneātUs, “ lined ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0AFFED1DDBEB24FDFDFF2F.taxon	discussion	Remarks. Now Tetrastemma albolineatum (Timofeev, 1911) (Gibson 1995: 493). See Annex 2 for an English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBED31FE9AFD53.taxon	description	Source. In the binomen Prostoma armatum by Dugès (1830: 74).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBED31FE9AFD53.taxon	materials_examined	Type locality. Mediterranean; rocky intertidal, under stones.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBED31FE9AFD53.taxon	etymology	Etymology. Latin adjective, armātUs, - a, - um, meaning “ armed, equipped, fortified, armoured ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBED31FE9AFD53.taxon	discussion	Remarks. Prostoma armatum Dugès, 1830 was synonymized with Emplectonema echinoderma (Marion, 1873) by Bürger (1904: 23). At the same time, Bürger (1904: 67) introduced Prostoma quatrefagesi Bürger, 1904 as a new replacement name for Polia armata Quatrefages, 1846 to avoid putative homonymy with Prostoma armatum Dugès, 1830. However, because the two nominal species Prostoma armatum Dugès, 1830 and Polia armata Quatrefages, 1846 were not regarded congeneric by Bürger (1904), the replacement name Prostoma quatrefagesi Bürger, 1904 was unnecessary.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEEEDFBF3FBCF.taxon	description	Source. In the binomen “ Prostomo aseptata ” by Friedrich (1935: 17); cf. Article 11.9.3.2 (combination with the correct original spelling of the generic name).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEEEDFBF3FBCF.taxon	materials_examined	Type locality. Kiel Bay, Germany.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEEEDFBF3FBCF.taxon	etymology	Etymology. Adjective, - us, - a, - um; from the negative prefix a -, the Latin neuter noun sēptUm (genitive sēptī), and the adjective-forming suffix - ātUs, referring to the supposed absence of the precerebral septum.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEEEDFBF3FBCF.taxon	discussion	Remarks. The original spelling has been mandatorily changed according to Articles 31.2 and 34.2 (gender agreement). Now Tetrastemma aseptatum (Friedrich, 1935) (Friedrich 1955: 169).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBE891FBF8FA3B.taxon	description	Source. In the binomen “ Prostoma Beaumonti ” by Southern (1913: 17, pl. I, fig. 3 A – C); cf. Article 32.5.2.5 (initial upper-case letter must be replaced with a lower-case letter).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBE891FBF8FA3B.taxon	materials_examined	Type locality. Clare Island, Ireland: Blacksod Bay (2 fathoms), Lough Swilly (7 – 10 fathoms), Galway Bay (1 – 3 fathoms), and Valencia Harbour (8 – 9 fathoms).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBE891FBF8FA3B.taxon	etymology	Etymology. Masculine noun in the genitive case, after Walter Ibbotson Beaumont (born in 1861 or 1862; died on 3 May 1912, drowned in a sailing accident at Tarbert, Loch Fyne), a British faunist (Hansson 1997).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBE891FBF8FA3B.taxon	discussion	Remarks. Now Tetrastemma beaumonti (Southern, 1913) (Gibson 1982: 158).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEA04FDFDF8D3.taxon	description	Source. In the binomen Prostoma bipeltatum by Timofeev (1911: 38, fig. 8).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEA04FDFDF8D3.taxon	materials_examined	Type locality. Villefranche-sur-Mer.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEA04FDFDF8D3.taxon	etymology	Etymology. Adjective, bipeltātUs, - a, - um; from the prefix bi-, “ having two parts; occurring twice ”, and the adjective peltātUs, “ armed with a pelta; shield-bearing ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFED1DDBEA04FDFDF8D3.taxon	discussion	Remarks. Now Tetrastemma bipeltatum (Timofeev, 1911) (Gibson 1995: 494). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFEA1DDBEB6DFDFDFEBB.taxon	description	Source. In the binomen Prostoma bistriatum by Timofeev (1911: 36, fig. 3).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFEA1DDBEB6DFDFDFEBB.taxon	materials_examined	Type locality. Villefranche-sur-Mer.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFEA1DDBEB6DFDFDFEBB.taxon	etymology	Etymology. Adjective, bistriātUs, - a, - um; from the prefix bi-, “ having two parts; occurring twice ”, and the adjective striātUs, “ furrowed; grooved, fluted, striated ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0BFFEA1DDBEB6DFDFDFEBB.taxon	discussion	Remarks. Now Tetrastemma bistriatum (Timofeev, 1911) (Gibson 1995: 494). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBED84FC61FD7F.taxon	description	Source. In the binomen “ Prostoma brunnea ” by Friedrich (1935: 16).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBED84FC61FD7F.taxon	materials_examined	Type locality. Kiel Bay, Germany.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBED84FC61FD7F.taxon	etymology	Etymology. Latin adjective, - us, - a, - um, meaning “ brown ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBED84FC61FD7F.taxon	discussion	Remarks. The spelling has been mandatorily changed according to Articles 31.2 and 34.2 (gender agreement). Now Tetrastemma brunneum (Friedrich, 1935) (Friedrich 1955: 168).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEEC1FBEBFC5F.taxon	description	Source. In the binomen Prostoma dutoiti by Wheeler (1940 a: 39, fig. 10 A – D).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEEC1FBEBFC5F.taxon	materials_examined	Type locality. Bats Cave Rocks, East London, South Africa.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEEC1FBEBFC5F.taxon	etymology	Etymology. Masculine noun in the genitive singular, after C. A. du Toit	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEEC1FBEBFC5F.taxon	discussion	Remarks. Now Tetrastemma dutoiti (Wheeler, 1940) (Wheeler, 1940 b: 236).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEFE1FAD4FAF7.taxon	description	Source. In the binomen “ Prostoma Herouardi ” by Oxner (1908: 1, figs 1 – 3); cf. Article 32.5.2.5 (initial upper-case letter must be replaced with a lower-case letter).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEFE1FAD4FAF7.taxon	materials_examined	Type locality. Roscoff, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEFE1FAD4FAF7.taxon	etymology	Etymology. Masculine noun in the genitive singular, after the holothurian specialist Edgard Joseph Émile Hérouard (1858 – 1932), who in 1902 became sous-directeur de la Station biologique de Roscoff (Hansson 1997).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEA1DDBEFE1FAD4FAF7.taxon	discussion	Remarks. Now Tetrastemma herouardi (Oxner, 1908) (Marine Biological Association 1957: 107).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEB1DDBEAD1FEBAFE73.taxon	description	Source. In the binomen Prostoma maculatum by Timofeev (1911: 38, fig. 7).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEB1DDBEAD1FEBAFE73.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEB1DDBEAD1FEBAFE73.taxon	etymology	Etymology. Latin adjective, macUlātUs, - a, - um, meaning “ stained, spotted ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0CFFEB1DDBEAD1FEBAFE73.taxon	discussion	Remarks. Gibson (1995: 497, 525) replaced Prostoma maculatum Timofeev, 1911 [“ Timofeeva, 1912 ” in Gibson (1995)] with Tetrastemma timofeevai Gibson, 1995, with an intention to avoid secondary homonymy between Tetrastemma maculatum Sumner, 1894. However, the latter had been synonymized with Oerstedia nigra (Riches, 1893) by Bürger (1904: 72). The two nominal species Tetrastemma maculatum Sumner, 1894 and Prostoma maculatum Timofeev, 1911 were thus no longer considered congeneric as of 1995. Therefore, Tetrastemma timofeevai Gibson, 1995 is a junior synonym of Tetrastemma maculatum (Timofeev, 1911) according to Article 59.4, which stipulates that a “ species-group name rejected after 1960 on grounds of secondary homonymy is to be reinstated as valid by an author who considers that the two species-group taxa in question are not congeneric ”. Timofeev’s taxon should be referred to as Tetrastemma maculatum (Timofeev, 1911). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEF09FAE5FB13.taxon	description	Source. As a replacement name for Polia armata Quatrefages, 1846 by Bürger (1904: 67).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEF09FAE5FB13.taxon	materials_examined	Type locality. Sicily, Italy.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEF09FAE5FB13.taxon	etymology	Etymology. Masculine noun in the genitive singular, after Jean Louis Armand de Quatrefages de Bréau (1810 – 1892), a French biologist.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEF09FAE5FB13.taxon	discussion	Remarks. Bürger (1904: 67) replaced Polia armata Quatrefages, 1846 with Prostoma quatrefagesi Bürger, 1904, with an intention to avoid secondary homonymy with Prostoma armatum Dugès, 1830. However, Bürger (1904: 23) placed Prostoma armatum Dugès, 1830 in a synonymy of Emplectonema echinoderma (Marion, 1873). The two species were, and have been, not regarded conspecific. Article 59.3 states that “ A junior secondary homonym replaced before 1961 is permanently invalid unless the substitute name is not in use and the relevant taxa are no longer considered congeneric, in which case the junior homonym is not to be rejected on grounds of that replacement ”. The species should now be Tetrastemma quatrefagesi (Bürger, 1904) (Gibson 1995: 523).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBE92DFD0CF9AB.taxon	description	Source. As the binomen Prostoma roseocephalum submitted by Okuda in Okada et al. (1947: 1469, fig. 4141 [1 – 4]), with Yamaoka attributed as the naming authority.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBE92DFD0CF9AB.taxon	materials_examined	Type locality. Under stones and among algal holdfasta; Shimoda, Japan.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBE92DFD0CF9AB.taxon	etymology	Etymology. Adjective, from roseus (“ rosy ”) and - cephalus (“ headed ”), indicating the reddish cephalic patch.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBE92DFD0CF9AB.taxon	discussion	Remarks. Now Tetrastemma roseocephalum (Yamaoka, 1947) (Crandall et al. 2001). Tetrastemma yamaokai Iwata, 1954 is its junior synonym (Kajihara 2017).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEDCDFE02FD37.taxon	description	Source. In the binomen Prostoma mixtum by Timofeev (1911: 36, fig. 4).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEDCDFE02FD37.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEDCDFE02FD37.taxon	etymology	Etymology. Latin adjective, mixtus, - a, - um, meaning “ mixed ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEDCDFE02FD37.taxon	discussion	Remarks. Now Tetrastemma mixtum (Timofeev, 1911) (Gibson 1995: 497). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEAB5FE02F86F.taxon	description	Source. In the binomen Prostoma simplex by Timofeev (1911: p. 39, fig. 9).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEAB5FE02F86F.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEAB5FE02F86F.taxon	etymology	Etymology. Latin adjective, simplex, simplex, simplex, meaning “ simple ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0DFFEB1DDBEAB5FE02F86F.taxon	discussion	Remarks. Now Tetrastemma simplex (Timofeev, 1911) (Gibson 1995: 498). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEC80FC29FDC7.taxon	description	Source. In the binomen Prostoma spectaculum by Yamaoka (1940: 16, fig. 3 A, B).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEC80FC29FDC7.taxon	materials_examined	Type locality. Naha and Chinen, Okinawa, Japan.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEC80FC29FDC7.taxon	etymology	Etymology. Latin neuter noun in the nominative singular (spectācUlUm; genitive spectācUlī), meaning “ show, spectacle; public or civic event ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEC80FC29FDC7.taxon	discussion	Remarks. Now Prosadenoporus spectaculum (Yamaoka, 1940) (Maslakova & Norenburg 2008: 1718). I have used this specific name with the ending - us (e. g., Kajihara 2017, 2020), which, however, should be regarded as an incorrect subsequent spelling (Article 33.3). None of the Latin dictionaries available to me contain an adjective such as ‘ spectaculus ’, and Article 31.2.2 states: “ When the author of a species-group name did not indicate whether he or she regarded it as a noun or as an adjective, and where it may be regarded as either and the evidence of usage is not decisive, it is to be treated as a noun in apposition to the name of its genus ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEE98FD2AFB3F.taxon	description	Source. In the binomen Prostoma suhmi as a replacement name for Tetrastemma fuscum Willemoes-Suhm in Tizard et al., 1885 by Bürger (1904: 66).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEE98FD2AFB3F.taxon	materials_examined	Type locality. Between Bermuda and the Azores, on the body of the grapsid crab Planes minutus (Linnaeus, 1758).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEE98FD2AFB3F.taxon	etymology	Etymology. Masculine noun in the genitive singular, after Rudolf von Willemoes-Suhm (1847 – 1875), a German naturalist served aboard the Challenger expedition.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBEE98FD2AFB3F.taxon	discussion	Remarks. Bürger (1904: 66) replaced Tetrastemma fuscum Willemoes-Suhm in Tizard et al., 1885 with Prostoma suhmi Bürger, 1904 to avoid primary homonymy with Tetastemma fuscum Örsted, 1843. Tetrastemma fuscum Örsted, 1843 was described from the Swedish island of Ven (Hven) in the Øresund strait, and synonymized with Oerstedia dorsalis (Abildgaard, 1806) by Bergendal (1900: 587). Tetrastemma fuscum Willemoes-Suhm in Tizard et al., 1885 was reported as an unidentified species of Tetrastemma by Willemoes-Suhm (1874), ectoparasitic on the crab Nautilograpsus minutus (Linnaeus, 1758) [now Planes minutus (Linnaeus, 1758)] (Tizard et al. 1885: 169). Willemoes-Suhm’s taxon is now known as Tetrastemma suhmi (Bürger, 1904) (Gibson 1995: 498, 525), although it is likely a member of Carcinonemertidae.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBE900FE3BF9AB.taxon	description	Source. In the binomen “ Prostoma tutus ” by Monastero (1931: 59, fig. 8).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBE900FE3BF9AB.taxon	materials_examined	Type locality. A beach in Sferracavallo, Sicily, Italy.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBE900FE3BF9AB.taxon	etymology	Etymology. Latin adjective, tūtUs, - a, - um, meaning “ safe, prudent; secure; protected ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE81DDBE900FE3BF9AB.taxon	discussion	Remarks. Now Tetrastemma tutum (Gibson 1995: 498, as “ Tetrastemma tutus ”), with the ending of the specific name being mandatorily changed in accordance with Articles 31.2 and 34.2. Monastero’s work on nemerteans from the coast of Palermo was published in Volume 16 of the third series of Atti della reale accademia di scienze, lettere e belle arti di Palermo in 1931.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE91DDBEAB4FEECFEBB.taxon	description	Source. As a substitute name for Tetrastemma roseum Verrill, 1892 by Bürger (1904: 58).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE91DDBEAB4FEECFEBB.taxon	materials_examined	Type locality. Off Block Island, 22 fathoms; Rhode Island, USA.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE91DDBEAB4FEECFEBB.taxon	etymology	Etymology. Masculine noun in the genitive singular, after Addison Emery Verrill (1839 – 1926), an American zoologist.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0EFFE91DDBEAB4FEECFEBB.taxon	discussion	Remarks. Bürger (1904: 58) replaced Tetrastemma roseum Verrill, 1892 with Prostoma verrilli Bürger, 1904 to avoid secondary homonymy with Nemertes rosea Kölliker, 1845 [originally in incorrect spelling “ roseus ”]. At the same time, Bürger (1904: 65) uncertainly placed Nemertes rosea Kölliker, 1845 in a synonymy of Prostoma helvolum (Bürger, 1895), the latter is now Tetrastemma helvolum Bürger, 1895 (Gibson 1995: 495). Apparently, Bürger (1904) regarded Nemertes rosea Kölliker, 1845 as a nomen dubium; otherwise, the taxonomic taxon encompassing the nominal taxon Tetrastemma helvorum Bürger, 1895 should have been referred to as Tetrastemma roseum (Kölliker, 1845). Gibson (1995: 499) listed Tetrastemma verrilli (Bürger, 1904) as a valid name for Verrill’s (1892) taxon.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBED85FE02FD53.taxon	description	Source. In the binomem Prostoma viera by Timofeev (1911: 37, fig. 5).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBED85FE02FD53.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBED85FE02FD53.taxon	etymology	Etymology. Uncertain; possibly a female given name in the Slavic languages, meaning “ faith ”; herein regarded as indeclinable according to Article 31.2.3.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBED85FE02FD53.taxon	discussion	Remarks. Now Tetrastemma viera (Timofeev, 1911) (Gibson 1995: 499). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBEEEDFE02FC17.taxon	description	Source. In the binomen Prostoma viperula by Timofeev (1911: 38).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBEEEDFE02FC17.taxon	materials_examined	Type locality. Villefranche-sur-Mer, France.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBEEEDFE02FC17.taxon	etymology	Etymology. Noun, from the Latin feminine vīpera, “ viper ”, and the diminutive suffix - ula.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBEEEDFE02FC17.taxon	discussion	Remarks. Now Tetrastemma viperula (Timofeev, 1911) (Gibson 1995: 499). See Annex 2 for English translation of the original description.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBE829FC7BF8FF.taxon	description	Source. As a new replacement name for Oerstedia vittata Hubrecht, 1879 by Bürger (1904: 59).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBE829FC7BF8FF.taxon	materials_examined	Type locality. Naples, Italy.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBE829FC7BF8FF.taxon	etymology	Etymology. Adjective, vittiger, vittigera, vittigerum; from the Latin feminine noun vitta, “ band, ribbon ”, and the suffix - ger, meaning “ - bearing, - carrying ”.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D0FFFE91DDBE829FC7BF8FF.taxon	discussion	Remarks. Bürger (1904: 59) replaced Oerstedia vittata Hubrecht, 1879 with Prostoma vittigerum Bürger, 1904 to avoid secondary homonymy with Tetrastemma vittatum Verrill, because Bürger (1904) regarded the two nominal species being placed in Prostoma. If Tetrastemma vittatum Verrill, 1874 is conspecific with Cosmocephala cordiceps Jensen, 1878 — as suggested by Brunberg (1964) and Norenburg (1986) — then this taxon should be referred to as Cyanophthalma vittata (Verrill, 1874), instead of Cyanophthalma cordiceps (Jensen, 1878) (cf. Gibson 1995: 527; Junoy et al. 2011: 622; Hookabe & Kajihara 2020: 268). Hubrecht’s (1879) taxon from Naples, Italy, is now Tetrastemma vittigerum (Bürger, 1904) (Kirsteuer 1963: 591). Recent molecular phylogenetic analyses have suggested that specimens collected in Spain (Kvist et al. 2014) and France (Chernyshev et al. 2021) identified as T. vittigerum are closely related to Vieitezia luzumurbeae Junoy et al., 2010. The two names vittigerum Bürger, 1904 and vittatum Verrill, 1874 will likely be combined respectively with Vieitezia (Chernsyshve et al. 2021) and Cyanophthalma (Hookabe & Kajihara 2020: 268) when sufficient data become available. In that case, the secondary homonymy between vittata Hubrecht, 1879 (replaced with vittigerum Bürger, 1904) and vittatum Verrill, 1874 will be resolved. Even in that case, vittata Hubrecht, 1879 remains permanently invalid in accordance with Article 59.3, because the substitute name vittigerum Bürger, 1904 is currently in use.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D30FFD41DDBEAD1FD58F829.taxon	description	(Annex Fig. 1 A) Description. Yellowish-white nemertean, with transparent pink digestive canal. Length 9 – 12 mm. Head slightly widened, posteriorly tapering significantly; head slightly demarcated from remaining body. Eyes large; anterior eyes closely set to each other. Basis 1.5 times longer than main stylet. Locality. One male and two females were found in sand on the beach near the laboratory (Annex Fig. 2, XII).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D30FFD41DDBEAD1FD58F829.taxon	discussion	Remarks. The original figure (рис. 1) shows two accessory stylet pouches, each containing four accessory stylets. ANNEX FIGURE 1. Original drawings of 10 species established by Timofeev (1911): A, Nemertopsis capitulata Timofeev, 1911; B, Amphiporus nigrostriatus Timofeev, 1911; C, Tetrastemma bistriatum (Timofeev, 1911); D, Tetrastemma mixtum (Timofeev, 1911); E, Tetrastemma viera (Timofeev, 1911); F, Tetrastemma albolineatum (Timofeev, 1911); F', yellow variety of T. albolineatum with white cephalic glands along with the mid-dorsal stripe forming a cruciform marking on the head; G, Tetrastemma maculatum (Timofeev, 1911); H, Tetrastemma bipeltatum (Timofeev, 1911); I, Tetrastemma simplex (Timofeev, 1911); J, Paralineus elisabethae Schütz, 1911; modified from Timofeev (1911). ANNEX FIGURE 2. Map of the Bay of Villefranche-sur-Mer showing 25 sampling points in Timofeev (1911) indicated with Roman numerals; modified from Timofeev (1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEC80FE99FE2B.taxon	description	(Annex Fig. 1 B) Description. Small nemertean up to 10 mm long; gray or grayish brown in colour, with large brown spot on head and pronounced dark-brown stripe on dorsal surface of body. Locality. Sublittoral, silt, together with Cephalotnrix from ca. 16 – 18 m depth (Annex Fig. 2, III, dredging number 44). Two specimens were found, both males.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEC80FE99FE2B.taxon	discussion	Remarks. The original figure (рис. 2) shows two accessory stylet pouches, each containing two to three accessory stylets.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEE34FCB4FC5F.taxon	description	(Annex Fig. 1 C) Description. Very small nemertean, approximately 6 mm long and 0.5 mm wide. Body white with yellowish tint. Two dark-brown stripes running dorsally, separated by wide area darker than rest of body, in middle of which narrow, shiny-white strip of glandular cells stretches. Dark-brown half-ring present behind posterior pair of eyes, from which aforementioned two dorsal stripes extend. Cephalic gland in form of white spot between eyes. At posterior end of body, white anal gland also present. Locality. Two specimens, sublittoral silt at 16 – 18 m depth (Annex Fig. 2, III, dredging number 44).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEE34FCB4FC5F.taxon	discussion	Remarks. The original figure (рис. 3) shows two accessory stylet pouches, each containing two and three accessory stylets; now Tetrastemma bipeltatum (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEFE0FD1DFA3B.taxon	description	(Annex Fig. 1 D) Description. Body length from 10 to 25 mm, width up to 0.7 mm. Body slightly thickened in middle, rounded. Head slightly separated from remaining body. Body colour yellowish, with pink or brown tint. Dark brown cephalic patch present behind anterior pair eyes, often covering the latter; bright white spot (sometimes divided into two) of cephalic gland present in front of cephalic patch. Behind cephalic patch, transversely accumulated glands of white strip present, from which white glandular strip extends posteriorly, stretching across entire dorsum of animal, reaching anal gland. Locality. Sublittoral silt at 16 – 18 m depth (Annex Fig. 2, II, III, IV, V). Darse, muddy silt, 5 m deep (Annex Fig. 2, VI).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEFE0FD1DFA3B.taxon	discussion	Remarks. The original figure (рис. 4) shows two accessory stylet pouches, each containing two to four accessory stylets; now Tetrastemma mixtum (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEA04FE5DF86C.taxon	description	(Annex Fig. 1 E) Description. Body about 10 mm long, cylindrical in shape; head not demarcated from remaining body; posterior end rounded. Main colour dirty yellow. Immediately behind posterior pair of eyes, wide ring of dotted, yellowbrown pigment present; from this ring, narrow stripe of similar pigment stretches dorsally. Eyes six; small grain of additional pigments (same as eye pigments) present around each of eyes in middle pair. Locality. Silt from a depth of 150 m at the exit of the bay (Annex Fig. 2, XXIV, dredging number 38).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D33FFD51DDBEA04FE5DF86C.taxon	discussion	Remarks. The original figure (рис. 5) shows two accessory stylet pouches, each containing three accessory stylets; now Tetrastemma viera (Timofeev, 1911), although the three pairs of eyes suggest that this species may not belong in Tetrastemma.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEC80FC50FC5F.taxon	description	(Annex Fig. 1 F, F') Description. Body length up to 12 mm. Head slightly widened. Body rather wide in middle, tapering towards posterior end. Main body colour beautiful pinkish-purple. Body transparent; alimentary canal shiny orange, sometimes brick-red, disguising delicate basement colour of animal. Wide, bright, white stripe (green in transmitted light) running on dorsal surface, narrowing towards both ends of body, especially posteriorly; in middle portion of body, it reaches greatest, sometimes significant, width; occasionally, at front end of body (on head), this stripe is very weakly expressed, until it almost disappears completely. Eyes orange; cephalic furrows sometimes tinged with reddish-red colour. In epidermis, grains of reddish pigments often noticeable, sometimes so densely that entire body seems to be reddish, retaining basement purple colour only on head. In addition to the pinkish-purple Prostoma albolineata (Annex Fig. 1 F), there is a yellow, differently coloured Prostoma occurring in sublittoral silt, which I attribute to the same species, because often the latter is not different, except for colour, from the above-described P. albolineatum. Sometimes the white stripe on the dorsal surface does not stand out sharply against the yellow background of the body; sometimes it is narrower than that of the violet form, and sometimes a white cephalic gland is located between the four eyes, merging with the stripe, so that the white stripe on the head anteriorly has a kind of cruciform expansion (Annex Fig. 1 F'). Localities. Coastal algae with hydroids (Annex Fig. 2, XX, XXII). Off Darse, dirty silt, 5 m deep (Annex Fig. 2, VI). Sublittoral, silt, depths 16 – 18 m (Annex Fig. 2, II, III, IV). Roots of Posidonia (Annex Fig. 2, XII, IX). Stones with bryozoans, 50 m depth (Annex Fig. 2, XXIII).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEC80FC50FC5F.taxon	discussion	Remarks. The original figure (рис. 6 a, b) shows two accessory stylet pouches, each containing two or three accessory stylets; now Tetrastemma albolineatum (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEFE0FCBFF9AB.taxon	description	(Annex Fig. 1 G) Description. Body length up to 14 mm, width up to 0.5 mm. Head not separated from remaining body. Body thickest at posterior 1 / 3, ending blunt-conically. With distinct brown cephalic patch behind first pair of eyes, as in Prostoma coronatum. Clusters of shiny, white glands present behind and in front of cephalic patch. Body colour from dirty yellow to reddish, less often pinkish and brown; anterior end of body transparent. Dorsally, more-orless sharp, rather large, white spots with red greenish and bluish tints being obvious. With transmitted light, these spots are transparent, delicate, pinkish-red colour, sometimes little noticeable. Location of spots on dorsal surface variable: sometimes arranged medially in single, sparse row; or 2 – 3, randomly located rows along midline; or sometimes scattered along the back without order (as in the attached figure). Rarely, smaller white specks of glands are mixed with the spots. Localities. Dirty silt, off Darse (Annex Fig. 2, VI). Sublittoral, silt, depth 16 – 18 m (Annex Fig. 2, II). Among roots of Posidonia (Annex Fig. 2, VII, VIII, IX). Small gravel with shells, depth 40 m (Annex Fig. 2, XIX). Stones with bryozoans, 50 m (( Annex Fig. 2, XXIII).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEFE0FCBFF9AB.taxon	discussion	Remarks. The original figure (рис. 7) shows two accessory stylet pouches, each containing two or three accessory stylets; now Tetrastemma maculatum (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEAB4FC80F827.taxon	description	[No illustration in the original description] Description. Up to 20 mm long, about 0.5 mm wide. Extremely graceful nemertean with head weakly demarcated from body; body somewhat thicker than in middle portion, greenish, transparent; cephalic furrows coloured slightly reddish brown. Single, bright white mid-dorsal stripe (glandular) stretching from rear end of head to tail; irregularly shaped white processes laterally branching off from mid-dorsal stripe. Locality. Passable, among roots of Posidonia (Annex Fig. 2, IX). Quite abundant.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D34FFD21DDBEAB4FC80F827.taxon	discussion	Remarks. Now Tetrastemma viperula (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D35FFD31DDBEC80FCB4FDC7.taxon	description	(Annex Fig. 1 H) Description. Very small nemertean, up to 8 mm in length. Body thin, round, gradually tapering slightly towards both ends. Alimentary canal delicate pink, transparent, visible through carmine-red colour [of basement body?]. Large, brown cephalic patch behind anterior pair of eyes. Shiny white anal glands with same shape as cephalic patch present at posterior end of the body is a. In front and behind the head pigment spot, there is an accumulation of white, glandular cells. Rather bright, orange-yellow mid-dorsal stripe, formed by epidermal pigments, running for entire body. Locality. Stones with bryozoans, 50 m deep (Annex Fig. 2, XXIII), 5 specimens.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D35FFD31DDBEC80FCB4FDC7.taxon	discussion	Remarks. The original figure (рис. 8) shows two accessory stylet pouches, each containing two or three accessory stylets; now Tetrastemma bipeltatum (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D35FFD31DDBEE98FD22FC33.taxon	description	(Annex Fig. 1 I) Description. Up to 9 mm long and 0.6 mm wide. Small nemertean, relatively long, rather thick. Body anteriorly barely narrowed, posteriorly thick, ending bluntly. Body colour white, with light, yellowish tint; almost opaque, no marks. By the shape of the body, it is better to attribute it to the genus Oerstedia. Locality. Sand with small, broken shells, 35 – 40 m deep (Annex Fig. 2, XV), abundant.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D35FFD31DDBEE98FD22FC33.taxon	discussion	Remarks. The original figure (рис. 9) shows two accessory stylet pouches, each containing three accessory stylets; now Tetrastemma simplex (Timofeev, 1911).	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
03B9420C1D36FFD01DDBEC80FF77FE0C.taxon	description	[No illustration in the original description] Description. Body 18 to 35 mm long and about 1 mm wide. Head, in area of lateral slits, slightly widened. Body brick in colour, with brownish or cherry tint. Ventrally only sometimes lighter than dorsal surface, but always coloured. Anterior end of head and edges of lateral slits white; tail transparent. Dorsally with about 16 narrow stripes, wider in middle, tapering to body edges. At cephalic tip, 5 – 6 black eyes clearly visible against background, located in two lateral groups. Localities. Sublittoral, silt, ca. 16 – 18 m depth (Annex Fig. 2, IV). Cabrette, sand with coralines, depth ca. 40 m.	en	Kajihara, Hiroshi (2025): A taxonomic revision of the freshwater monostiliferous hoplonemertean genus Prostoma Dugès, 1828 (Nemertea: Eumonostilifera): a radical solution or an over-lumping? Zootaxa 5646 (4): 451-500, DOI: 10.11646/zootaxa.5646.4.1, URL: https://doi.org/10.11646/zootaxa.5646.4.1
