Perinereis larentukana (Grube in Peters, 1881) Villalobos-Guerrero, 2019

Villalobos-Guerrero, Tulio F., 2019, Redescription of two overlooked species of the Perinereis nuntia complex and morphological delimitation of P. nuntia (Savigny in Lamarck, 1818) from the Red Sea (Annelida, Nereididae), Zoosystema 41 (24), pp. 465-496 : 483-488

publication ID	https://doi.org/ 10.5252/zoosystema2019v41a24
publication LSID	urn:lsid:zoobank.org:pub:9347D7C7-1D9D-4682-A9B9-BD7E11AF97B4
DOI	https://doi.org/10.5281/zenodo.4439498
persistent identifier	https://treatment.plazi.org/id/03B28785-F469-BE51-A7BF-A5F9FB7C75C4
treatment provided by	Felipe
scientific name	Perinereis larentukana
status	comb. nov.

Treatment

Perinereis larentukana View in CoL (Grube in Peters, 1881), reinst., n. comb.

( Figs 1 View FIG G-I; 8A-L; 9A-F)

Nereis (Neanthes) larentukana Grube in Peters, 1881: 110-111 View in CoL .

Neanthes larentukana View in CoL – Hartman 1959: 250. — Wiktor 1980: 273.

Nereis larentukana View in CoL – Hartwich 1993: 111.

Perinereis nuntia View in CoL – Wilson & Glasby 1993: 266-268, fig. 11a-g. — Glasby & Hsieh 2006: 563-565, fig. 6a-f (partim, non Savigny in Lamarck, 1818).

TYPE MATERIAL. — 7 syntypes of Nereis (Neanthes) larentukana : 1 specimen, MPW 411, labelled as “ holotypus lub syntypus ”, in poor condition; 4 specimens, ZMB 863, labeled as “ Syntypen ”, in good conditions; two specimens ( ZMB 4002-Q), labeled as “ Syntypen ”, in poor conditions. All collected by E. K. von Martens, from Larantuka, Flores, East Nusa Tenggara, Indonesia, no further data but see remarks and Appendix.

DIAGNOSIS. — Specimens with antennae joined, nuchal organs 3 times longer than posterior eyes, postero-dorsal tentacular cirri reaching chaetigers 2-3. Jaws with 2 canals. Maxillary ring: AI= 2-3; AII = 7-9; AIII = 9-17, 1 lateral cone; AIV = 20-28, merged paragnaths absent. Oral ring: AVI-V-VI pattern, υ- shaped; AV =3-4, paragnaths behind AVI; AVI = 4-8, arc short, regular, bars short, even, except inner one slightly longer; AVII-VIII = 26-34, 2 transverse rows, proximal with large cones. Gap between AVI and AVII-VIII broad. Dorsal cirri short, one-half length of dorsal ligule, inserted posteriorly on two-thirds of it. Dorsal ligule even throughout body, subequal to median ligule; distal lobe bluntly conical posteriorly. Ventral cirri short, digitiform. Homogomph spinigers with blade finely serrated, evenly spaced; absent in subacicular neurochaeta. Heterogomph spinigers such as notopodial; absent in a few anterior chaetigers. Heterogomph falcigers with short and medium blades.

HABITAT. — Unknown.

TYPE LOCALITY. — Larantuka, Flores, East Nusa Tenggara, Indonesia.

DISTRIBUTION. — West Timor, East Flores (East Nusa Tenggara); Ambon ( Moluccas); Besuki (East Java).

DESCRIPTION

Measurements. Syntype, ZMB 863, atoke, lacking posterior region, LT= 127 (216-235) mm, L15 = 21.1 (17-25.3) mm, W15=4.3 (3.6-4.6) mm, and 117 (154-192) chaetigers.

Pigmentation. Body epidermal pigmentation faded, some slight traces of pale brown pigmentation in prostomium and posterior parapodia. Brownish glandular patches in ligules, most intense posteriorly ( Fig. 9E, F View FIG ).

Head. Prostomium sub-pentagonal, narrow anterior end ( Fig. 8A, B View FIG ), 1.3 times wider than long; anterolateral sides 2 times wider than antennal diameter. Palpophores cylindrical ( Fig. 8A View FIG ), thick, 1.2 times longer than wide, nearly equaling entire length of prostomium; one deep wrinkle placed horizontally in one-half of palpophore. Antennae joined ( Fig. 8A, B View FIG ), gap one-sixth of antennal diameter; digitiform, barely sharpened tip, slightly thickened, extending backward to nearly one-half of prostomium. Eyes in sub-trapezoidal arrangement, blackish, anterior and posterior pairs well separated (1.6 times size of posterior; Fig. 8B View FIG ); lens barely visible, purplish. Anterior pair of eyes reniform, nearly subequal to antennal diameter; lens oval, located anterolaterally, touching margin of eye, covering 50%. Posterior pair of eyes rounded, subequal to anterior pair; lens rounded, located posterolaterally, not touching margin, covering 60%. Nuchal organs deeply embedded, slightly oblique, notoriously long, 3 times longer than posterior eyes ( Fig. 8B View FIG ).

Apodous anterior segment & tentacular cirri. Apodous anterior segment 3.3 (3.3-4.2) times wider than long, 1.2 (1.2- 1.4) times longer than chaetiger 1. Tentacular cirri pattern: Postero-dorsal cirri 1.5 times longer than antero-dorsal ones; anterior-ventral cirri slightly smaller than postero-ventral one. Antero-dorsal cirri reaching chaetiger 1 (1-2); antero-ventral 1.2 (1-1.3) times longer than palpophore. Postero-dorsal reaching chaetiger 3 (2-3); postero-ventral extending over prostomium to reach one-half of it. Dorsal cirrophores wrinkled, cylindrical; postero-dorsal cirrophores longest, 2.5 times length of postero-ventral cylindrical ones.

Pharynx. Not everted, previously dissected (description based on syntype with everted pharynx). Jaws blackish in distal third, then brownish; 8 (6-7) denticles, well-developed, 4 denticles ensheathed proximally, inner margin of fang flattened, equaling next 2.5 denticles; pulp cavity two-fifths length of jaw ( Fig. 8C View FIG ), distal apex leveling between first and second basal denticles; 2 longitudinal canals emerging from pulp cavity ( Fig. 8D View FIG ). Maxillary ring ( Fig. 8E View FIG ): paragnaths conical, none worn, reddish amber colored, slightly smaller than those in oral ring. AI=2 (2-3), longitudinal regular line, cones subequal to the longest of AII. AIIa =8 (7-9), AIIb=9 (4-10), oblique irregular patch, two irregular rows. AIII=13 (9-17), oval patch, three irregular transverse rows, one cone laterally isolated in each side. AIVa =21 (21-26), AIVb= 20 (20-28), lemniscateshaped patch, maxillary portion smaller than proximal one, inner cones smallest; merged paragnaths absent. Oral ring ( Figs 1 View FIG G-I, 8F-H): AVI-V-VI pattern, υ- shaped ( Figs 1 View FIG G-I, 8F); AVI not overlapping proximally AV. Paragnaths conical and shield-shaped bars, reddish and brownish amber colored. AV =3 (3-4), equilateral triangular patch, clearly isolated from those on AVI, brownish amber, distal cone slightly bigger. AVIa=7 (4-8), AVIb=6 (5-7), arc of paragnaths short, regular, reddish amber, shield-shaped bars; bars short, tip barely worn, subequal except inner one slightly longer than others ( Fig. 8G View FIG ); ridges barely prominent, narrow, three-quarters width of palpophore. AVII-VIII =26 (26-34), conical paragnaths, most of them placed in longitudinal wrinkles of ring ( Fig. 8H View FIG ); single band of two main transverse rows, increasing in number dorsoventrally from 1 to 2 rows, distal one regular with mainly big, reddish amber cones, proximal row irregular, zigzagged smaller, brownish amber cones. Gap between AVI and AVII- VIII broad, as wide as three-quarters width of palpophore.

Notopodia. Dorsal cirri digitiform throughout body; slightly longer than dorsal ligule in first parapodia, smaller than it from parapodia 5, three-quarters length of ligule in anterior parapodia, one-half from median ones; cirrus longer than length of proximal lobe of dorsal ligule in first parapodia ( Fig. 9A View FIG ), subequal to it in anterior ( Fig. 9B View FIG ), smaller from median ones ( Fig. 9 View FIG C-F); cirri inserted on one-third in anterior parapodia ( Fig. 9A, B View FIG ), one-half in median ( Fig. 9 View FIG C-E), two-thirds in posterior ones ( Fig. 9F View FIG ). Dorsal ligule similar throughout body; ligule 1.5 (1.5-1.8) times width of median ligule in posterior parapodia ( Fig.9F View FIG ). Distal lobe of dorsal ligule bluntly rounded in anterior parapodia, bluntly conical from median parapodia; distal lobe slightly longer than proximal one in first parapodia, subequal to it in anterior, four-fifths or three-fifths length of proximal from median ones ( Fig. 9 View FIG D-F). Dorsal ligule slightly shorter than median ligule in anterior parapodia ( Fig. 9B View FIG ), slightly longer than it from median ( Fig. 9 View FIG C-F). One main glandular patch in dorsal ligule, central, becoming darker and bigger from parapodia 45; oval, covering 25-30% in median parapodia ( Fig. 9D View FIG ); rounded, covering 50-60% in posterior ones ( Fig. 9F View FIG ). Notoacicular process poorly developed.

Neuropodia. Neuracicular ligule barely smaller than ventral throughout body; twice wider than ventral ligule in anterior parapodia, 3 times wider from median ones. Superior lobe digitiform, shorter than inferior lobe throughout body, projecting beyond end of neuracicular ligule only in first 6 parapodia (5-9), reduced from parapodia 16 (15-21). Inferior lobe rounded ( Fig. 9A, B View FIG ), narrowing progressively from parapodia 30 (28-33). Ventral ligule digitiform, shorter than median ligule throughout body, two-thirds length of ligule in anterior parapodia, one-half length from median ones. Ventral cirri digitiform, smaller than ventral ligule throughout body, leveling base of ligule, except in first 18 parapodia, one-half or two-fifths of ligule.

Chaetae. Notochaetae with homogomph spinigers, blade finely serrated towards toothed edge, evenly spaced. Neurochaetal supracicular fascicle with homogomph spinigers and heterogomph falcigers, both present throughout; spinigers as notopodial ones ( Fig. 8I View FIG ), as numerous as falcigers in same fascicle of anterior and median chaetigers, more than falcigers in posterior one; falcigers with short and medium blades (b/a =1-1.57 times), serrated region 0.31-0.35 of total blade length ( Fig. 8J View FIG ). Neurochaetal subacicular fascicle with heterogomph spinigers and heterogomph falcigers, spinigers absent in first 2 (2-7) chaetigers, falcigers present throughout body; spinigers with blade finely serrated towards toothed edge, evenly spaced, less numerous than falcigers in fascicle; falcigers with short and medium blades (b/a =1.05-1.62 times), serrated region 0.33-0.44 of total blade length ( Fig. 8K View FIG ).

Pygidium. Dehiscent but one complete syntype with short and thick anal cirri ( Fig. 8L View FIG ), as long as last 3 (2-5) chaetigers, cirrophores poorly developed.

REMARKS

Grube in Peters (1881) described Nereis (Neanthes) larentukana using specimens from Larantuka ( Indonesia) and collected by von Martens in January 1863 (see details in Appendix). The type material of N. (Neanthes) larentukana is currently lodged at the Museum of Natural History of the Wroclaw University (MPW) and at the ZMB ( Wiktor 1980; Hartwich 1993; Glasby & al Hakim 2017). It consists of seven syntypes that match accurately the original description that was based apparently in at least two specimens.

Grube (1874) proposed three groups within the subgenus Nereis (Lycoris) ; among them, a group lumping the N. nuntia related species, characterized by having several paragnaths in an arched row running towards the center of AV. Later, Grube in Peters (1881) considered the above concerning species in N. ( Neanthes ), which is also a member of the P. nuntia complex. It is still uncertain why Grube resumed using Neanthes as subgenus; however, it is probably that based on his 1874 work, he realized lately that N. nuntia group might represent other distinct but valid subgenus with Neanthes as representative. Perhaps, he followed the second group of Neanthes proposed by Kinberg (1865) for N. variegata (Grube & Örsted in Grube, 1858) (currently as Pseudonereis variegata ), which was regarded as having AV =3, just like N. (Neanthes) larentukana . However, Kinberg (1865) misinterpreted Grube’s original description of N. variegata on the oral ring: “annulus posterior […] supra singulis 3 juxtapositis”, transl. “posterior ring […] 3 single dorsal (paragnaths) placed close together” (Grube & Örsted in Grube 1858). According to Ehlers (1901), who examined the type specimen of N. variegata , and my revision on a topotype previously identified by Grube (ZMB 3671), the species has one large cone on AV and one single large compressed paragnath in each side of AVI. Intriguingly, it is noteworthy that Ehlers (1901) found, although very few, topotypes having three cones in a triangle or transverse row on AV.

The type material of N. (Neanthes) larentukana has not been examined since its description. Furthermore, the species has been scarcely addressed in the literature and commonly listed as Neanthes ( Hartman 1959; Fauchald 1972; Wilson 1984; Salazar-Vallejo et al. 2014; Glasby & al Hakim 2017); however, no details on its validity have been provided. After the examination of the type specimens, it is unveiled that N. (Neanthes) larentukana is a member of the P.nuntia species complex, mainly by having conical paragnaths on both pharyngeal rings, an arc of several shield-shaped paragnaths on AVI, notochaeta with only homogomph spinigers, and dorsal and median ligules slightly uneven throughout the body ( Wilson & Glasby 1993; Glasby & Hsieh 2006; this study). Therefore, it is regarded as a Perinereis species, P. larentukana n. comb.

Based on the revision of the type material of P. larentukana n. comb., and compared with the redescription of P. nuntia herein provided, these two species differ in several features. In P. larentukana n. comb., the AVI-V-VI pattern is υ- shaped ( Fig. 1H View FIG , 8G View FIG ); whereas in P. nuntia , it is χ- shaped ( Fig. 1 View FIG D-F, 2F). In P. larentukana n. comb., the dorsal cirrus from median parapodia is digitiform, shorter than dorsal ligule ( Fig. 9 View FIG C-F); whereas in P.nuntia it is cirriform, notoriously longer than ligule ( Fig. 2 View FIG I-K). In addition, in P. larentukana n. comb., the dorsal ligule from median parapodia is bluntly conical ( Fig. 9 View FIG C-F), whereas in P. nuntia the ligule is tapered and sharply pointed ( Fig. 2 View FIG I-K). Furthermore, P. larentukana n. comb. lacks heterogomph spinigers in the first few anterior chaetigers, whereas in P. nuntia this type of chaeta is present in all chaetigers. The heterogomph falcigers in P. larentukana n. comb. are shorter (b / a =1.05-1.62 times) and less serrated (serrated region 0.31- 0.44) than those in P. nuntia (b / a =1.37-2.15 times; serrated region 0.42-0.56). The nuchal organs are notoriously longer in P. larentukana n. comb. (3 times longer than posterior eye; Fig. 8B View FIG ) than those of P. nuntia (subequal to posterior eyes; Fig. 2A View FIG ). Likewise, P. larentukana n. comb. has two transverse rows of paragnaths on AVII-VIII ( Fig. 8H View FIG ), increasing from 1 to 2 in dorsoventral direction; whereas, P. nuntia has four rows ( Fig. 2E, G View FIG ), increasing from 2 to 4 in the same direction. Perinereis larentukana n. comb. has AIV =20-28, AVI= 4-8, and AVII-VIII =26-34; whereas P. nuntia has AIV =14-19, AVI = 8-10, and AVII-VIII=36-50. Complete specimens of P. larentukana n. comb. have a greater number of segments (154-192) than those of P. nuntia (109-127).

Among the species in the P. nuntia complex, P. larentukana n. comb. is similar to those species with dorsal cirri distinctly shorter than dorsal ligule. However, it is more closely related to P. heterodonta Gravier, 1899 ( Djibouti) and P. quatrefagesi ( Grube, 1878) (Bohol, Philippines), both previously referred as junior synonyms of P. nuntia ( Wilson & Glasby 1993) . Yousefi et al. (2011) recently reinstated the former species from the synonymy based on some specimens from near to the Gulf of Oman. They considered P.heterodonta as different from P.nuntia by lacking heterogomph spinigers in anterior neuropodia, by having shorter tentacular and dorsal cirri, AV =0-1, and AVII- VIII with fewer paragnaths (further differences, see remarks of P. nuntia ). However, the number of paragnaths on AIII, AIV and AVII-VIII from Iranian specimens also slightly differ from those from Djibouti. Due to these differences, the information of the original description and illustrations of P. heterodonta ( Gravier 1899, 1902) and the posterior characterizations with specimens from the type locality ( Gravier 1902; Fauvel 1919) were used to show that it differs from P. larentukana n. comb.

Despite P. larentukana n. comb. and P. heterodonta lack heterogomph spinigers in anterior chaetigers, they differ in several features. In P. larentukana n. comb., the AVI-V-VI pattern is υ- shaped; whereas in P. heterodonta , it is λ- shaped. In P. larentukana n. comb., the antennae are joined (gap onesixth of antennal diameter), whereas in P. heterodonta they are separated (gap subequal to antennal diameter). In addition, P. larentukana n. comb. has AV with 3-4 conical paragnaths, AVI with 4-8 shield-shaped bars in a regular transverse row, and AVII-VIII with 26-34 cones; whereas, in P.heterodonta , the AV lacks paragnaths, the arc of AVI has 10-18 shield-shaped bars obliquely disposed, and the AVII-VIII has 18 paragnaths, some are cones and others are p-bars. Likewise, P. larentukana n. comb. lacks heterogomph spinigers only in the first 1-7 chaetigers, whereas in P. heterodonta are lacking at least in the first 43 chaetigers. Finally, the postero-dorsal tentacular cirri are shorter in P. larentukana n. comb. (reaching chaetigers 2-3) than in P. heterodonta (reaching chaetigers 3-6).

Regarding P.quatrefagesi, Grube (1878) briefly described the species without illustrations and based on only one poorly preserved specimen from the Philippines; however, some relevant features were provided. For instance, some of the anterior end: antennae close enough to each other, shorter than one-half of prostomium; dorsal-most tentacular reaching chaetiger 5; AI with 3 paragnaths in a longitudinal row, AII with 7 in a circular patch, AIII with a transversely oval patch and 2 isolated cones, AIV with 18 paragnaths in 2-3 rows, AV with 1 cone, AVI with 8 bars in a transverse row, and AVII-VIII with 19 in 2 rows. Likewise, some features of parapodia; short, even throughout the body; the ligules are blunt, slightly tapered, with the dorsal ligule slightly broader, longer than median one, and ventral ligule small, rounded; dorsal cirrus short, almost one-half length of dorsal ligule; and among others.

Fauvel (1919) synonymized P. quatrefagesi transferring it into his group P. nuntia var. vallata . Later, Augener (1933) recognized the species as valid, but using specimens from the northern Moluccas and the description of Gnatholycastis brocki Ehlers, 1920 ( Ambon Island), which was regarded as a junior synonym of P. quatrefagesi ever since (e.g. Hartman 1959; Salazar-Vallejo et al. 2014). However, G. brocki is characterized by having a prostomium with a slightly incised distal end, a papilliform dorsal cirrus located distally on an expanded dorsal ligule in posterior parapodia, and an arc of paragnaths on AVI ( Ehlers 1920). This description, in fact, matches P. caeruleis ( Hoagland, 1921) (Sulawesi) rather than P. quatrefagesi , a species also recognized within the P. nuntia complex ( Wilson & Glasby 1993). Although the revision of the type material is needed, it is possibly that G. brocki and P. caeruleis are the same. If this is the case, the former name has priority over the latter (ICZN 1999, Art. 23.1), which has been erroneously dated as 1920 because of the cover page of the paper, but the volume of Hoagland’s work was in fact formally published until March 1921 ( True & Oesher 1947). Following the above, P. quatrefagesi was inaccurately regarded as valid. It is noteworthy that Glasby & Hsieh (2006) considered P. caeruleis as not belonging to the P. nuntia complex, such as other two species ( P. akuna and P. rhombodonta Wu, Sun & Yang, 1981 ), by the presence of pyramidal paragnaths on AVI, and a band of several rows of small cones separated from larger ones on AVII-VIII.

Perinereis quatrefagesi remained somewhat unnoticed in the literature until Hylleberg et al. (1986) examined in detail several atoke and epitoke specimens from the Gulf of Thailand. Their specimens fitted accurately the original description. They were different to P. brevicirris and P. nuntia , but Nereis (Perinereis) rumphii Horst, 1919 (Banda Sea) and P. weijhouensis Wu, Sun & Yang, 1981 (Guangxi, China) were referred as synonyms of P. quatrefagesi . Nevertheless, they may be regarded as independent species according to the original descriptions and Hylleberg et al. (1986) characterization.

Nereis (P.) rumphii differs from P. quatrefagesi in the shape of median parapodia in the epitoke female. The former species has a median ligule with an expanded lower-basal lamella and a ventral ligule with a sharp upper-basal projection, which are lacking in both ligules of P. quatrefagesi . Horst’s description of the atoke N. (P.) rumphii fits that provided above for P. larentukana n. comb., although the syntypes of the former species should be examined before regarding it as a junior synonym. Likewise, P. larentukana n. comb. differs from P. quatrefagesi because the former lack heterogomph spinigers in the first few anterior chaetigers, whereas this kind of chaeta is present throughout the body in P. quatrefagesi .

Also, P. weijhouensis is different from P. quatrefagesi because the dorsal cirrus is twice longer than dorsal ligule in posterior parapodia, the homogomph spinigers are in both neuropodial fascicles, and lacks heterogomph spinigers.Whereas in P. quatrefagesi , the dorsal cirrus is shorter than or nearly subequal to the ligule in same parapodia, the homogomph spinigers are present only in the neuropodial supracicular fascicle, and the heterogomph spinigers in the neuropodia. Perinereis weijhouensis was also synonymized with P. nuntia by Wilson & Glasby (1993), but it may also be raised from this synonymy taking in account the distribution pattern of spinigers mentioned above ( P. nuntia similar to that in P. quatrefagesi ); also, by having the arc of paragnaths on AVI clearly separated from each other (rows adjoining mid-dorsally in P. nuntia ).

Wilson & Glasby (1993) examined the holotype of P.quatrefagesi regarding it as a junior synonym of P. nuntia . No further details on its morphology were added to those mentioned in the original description, except that only a few chaetae are intact and the body is almost completely digested, remaining only the pale empty skin. Nevertheless, P. quatrefagesi herein is regarded as valid; it differs from P. nuntia by the length of dorsal cirrus, the mutual separation of arcs on AVI, and the number and arrangement of paragnaths on AVII-VIII. Perinereis quatrefagesi has dorsal cirrus shorter than or nearly subequal to the dorsal ligule in posterior parapodia, whereas in P. nuntia it is much longer (2-3 times) than ligule in same parapodia. In P. quatrefagesi , the arcs of paragnaths on AVI are clearly separated from each other by the broad ridge of AV; whereas in P. nuntia , the arcs of paragnaths on AVI nearly adjoin mid-dorsally by the narrow ridge of AV. Furthermore, the AVII-VIII in P. quatrefagesi has 19-36 paragnaths in up to 3 rows, whereas P. nuntia has 36-50 paragnaths in 4-5 rows.

Finally, Glasby & Hsieh (2006) extended the description of P. nuntia using material from several localities of the Indo-Pacific, illustrating a specimen from Singapore. However, it is evident that at least the Singaporean material belongs to a species closer to P. larentukana n. comb. and P. quatrefagesi , rather than P. nuntia . Some features of the anterior region looks alike to P. larentukana n. comb. / P. quatrefagesi (e.g. prostomium, antennae, dorsum of pharynx, among others). However, the slender dorsal cirrus, subequal to the dorsal ligule in posterior parapodia, and the absence of heterogomph spinigers in many anterior chaetigers, suggest that it is a different (possibly undescribed) species.