taxonID	type	description	language	source
03CB87F1FFB7FFBA31FDE77AFC36FBAE.taxon	type_taxon	Type genus. Dactylopleustes Karaman & Barnard, 1979: 112. Genera. Dactylopleustes Karaman & Barnard, 1979.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB7FFBA31FDE77AFC36FBAE.taxon	diagnosis	Diagnosis (from Bousfield & Hendrycks 1994, 1995 with additions). Body small, smooth, deep-plated. Urosomite 2 not occluded dorsally. Rostrum short. Eyes large, reniform. Antenna 1 short, pediform or subpediform. Accessory flagellum minute, one-articulate, scale-form. Upper lip: notch shallow, lobes only slightly or not asymmetrical. Lower lip with / without deep, distinct inner lobes. Mandibular molar small, rounded, non-triturative; right lacinia absent; palp article 2 short or not, article 3 without baso-facial A-setae. Maxilla 1: outer plate short, broad, with 11 – 30 apical strong pectinate setae (spine-like setae); inner plate with single apical seta; palp large, terminal article broad. Maxilla 2: plates short, subequal, inner plate with / without single stout seta along inner margin. Maxilliped: both plates short, weakly armed; palp articles short, article 4 pectinate. Coxal plates 1 – 4 deep, coxa 1 shortest. Coxal gills medium, sac-like on pereopods 2 – 4, plate-like on pereopods 5 – 6, lacking on pereopod 7. Gnathopods 1 and 2 small, slender, weakly subchelate: carpus and propodus elongate, longer in gnathopod 2; palmar margins short, lacking medial tooth, posterior margin variously setose; dactylus short, stout, as long as or overlapping palm. Pereopods 3 – 7 short; carpus and propodus with numerous short spine-like setae posteriorly in pereopods 3, 4 and anteriorly in pereopods 5 – 7; dactylus short, inner margin finely crenulate or pectinate. Pereopods 5 regularly homopodous; coxal plate regularly or strongly posterolobate; basis broad. Epimeral plates regular, unmodified. Uropod 1: rami subequal, broad-lanceolate. Uropods 2 and 3: rami unequal, outer ramus broad-lanceolate, the shorter than inner. Telson keeled proximally, apex rounded.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB7FFBA31FDE77AFC36FBAE.taxon	distribution	Distribution. Marine waters of boreal Pacific.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB7FFBA31FDE77AFC36FBAE.taxon	discussion	Remarks. Subfamily Dactylopleustinae is a monotypic taxon consisting of the genus Dactylopleustes only. Bousfield & Hendrycks (1994) showed the subfamily Dactylopleustinae to be related to the subfamilies Pleustinae Buchholz, 1874 and Pleusirinae Bousfield & Hendrycks, 1994, based on cladistic analysis. The subfamily Dactylopleustinae differs from the subfamily Pleustinae in the structures of rounded and non-triturative mandibular molar (columnar and triturative in Pleustinae) and maxilla 1 outer plate with 11 – 30 pectinate apical setae (9 pectinate setae in Pleustinae). The subfamily Dactylopleustinae differs from the subfamily Pleusirinae in the structures of maxilla 1 outer plate with 11 – 30 pectinate apical setae, inner plate with single apical seta (outer plate with 9 pectinate setae, inner plate without setae in Pleusirinae), and in the structure of gnathopods 1 and 2. According to the listed characteristics, the subfamily Dactylopleustinae is remote from Pleustinae and Pleusirinae. Bousfield & Hendrycks (1995) brought subfamily Dactylopleustinae closer together with the genus Parapleustes Buchholz, 1874 (subfamily Parapleustinae Bousfield & Hendrycks, 1994) based on the non-triturative molar of mandible and ordinary form of maxilliped. In my opinion, the genus Dactylopleustes is most similar in morphology to a genus Chromopleustes Bousfield & Hendrycks, 1995 (subfamily Parapleustinae), on the non-triturative molar of mandible, numerous pectinate apical setae on the outer plate of maxilla 1, ordinary form of maxilliped (outer plate with a few strong apical setae), and the shapes of gnathopods 1 and 2 (with elongate carpus and propodus). Thus, the subfamily Dactylopleustinae shares a common ancestor with the subfamily Parapleustinae. Species of the genus Dactylopleustes have peculiar antenna 1, mouthparts, gnathopods and pereopods specialized for commensal life clinging to globular sea urchins of the genus Strongylocentrotus Brandt, 1835 (Tzvetkova 1975; Bousfield & Hendrycks 1994, 1995). These characters, as well as the peculiar mixture of plesiomorphic and apomorphic features, confirm the allocation of the genus Dactylopleustes Karaman & Barnard, 1979 to a separate subfamily status of Dactylopleustinae (Bousfield & Hendrycks 1994, 1995).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB6FF8831FDE68DFA47FD2C.taxon	type_taxon	Type species. Parapleustes echinoicus Tzvetkova, 1975.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB6FF8831FDE68DFA47FD2C.taxon	diagnosis	Diagnosis (from Karaman & Barnard 1979; Barnard & Karaman 1991; Bousfield & Hendrycks 1995, with additions). Body small, smooth, lysianassiform; coxal plates deep, pereopods short. Rostrum short, about equal to latral head lobe. Inferior antennal sinus shallow. Antenna 1 short, not longer than antenna 2; peduncular article 2 shorter than article 1, article 3 very short. Antenna 2 pediform, flagellum shorter than peduncle. Mouthparts highly modified. Lower lip: inner lobes tall if present, outer lobes large, nearly horizontal. Mandibular molar process small, rounded, without triturating surface; left lacinia 5 – 9 - dentate, right lacinia absent; palp slender, article 1 short, without setae, article 2 weakly setose, article 3 with pectinate setae along inner margin. Maxilla 1: outer plate short, broad, apical setae numerous, slender, innermost seta strongest. Maxilla 2: outer plate with strong spine-like apical setae. Maxilliped: plates weakly armed; inner plate with / without a few tiny button-shape apical setae; outer plate, inner margin concave, apex weakly setose; palp short, article 1 almost as long as article 2, article 3 longest, with medio-distal row of setae, article 4 slender. Coxal plates 1 – 4 broad, much deeper than body plates (excluding D. longoantennis sp. nov.), coxal plate 1 distinctly smallest, not expanded distally; postero-distal cusps 2 – 5 per plate, small. Coxal gills largest on pereopods 3 – 5, smallest on pereopod 6. Gnathopods short, small, subequal in length, subsimilar, not sexually dimorphic; basis slender, anterior margin variously setose (more strongly in gnathopod 1); merus rounded distally; carpus subequal in length to propodus, variously setose posteriorly; propodus, palm very short, convex, with a few short spine-like setae at postero-distal angle, posterior margin long, with 2 – 4 groups of setae in gnathopod 1, 2 – 5 groups of setae in gnathopod 2; dactylus short, smooth. Pereopods 3 – 7 short; carpus and propodus with numerous short spine-like setae; dactylus very short, stout, inner margin nearly straight, finely crenulate or pectinate. Pereopods 5 – 7 regularly homopodous; coxal plate very deep, posterior lobe rounded below, basis broad, evenly rounded or with rounded obtuse angle behind. Epimeral plates medium deep, broad, ventral margin smooth or with a few tiny spine-like setae, postero-distal corner acuminate. Pleopod peduncle short, rami with variously reduced numbers of articles, not sexually dimorphic. Uropods 1 and 2 short, stout; rami sublanceolate, margins serially “ spinose ” (with tiny spine-like setae), tips without setae or with single spine-like seta (in D. obsolescens). Uropod 3: peduncle short, stout, rami broad-lanceolate, inner ramus larger than outer.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB6FF8831FDE68DFA47FD2C.taxon	distribution	Distribution. Marine waters of boreal Pacific.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB6FF8831FDE68DFA47FD2C.taxon	discussion	Remarks. Karaman & Barnard (1979) established a new genus Dactylopleustes with only the type species Parapleustes echinoicus Tzvetkova, 1975. The main distinguishing features of the genus after Karaman & Barnard (1979) were structures of dactylus of pereopods 3 – 7 (“ swollen, bearing large inferior distal notch and serrate or tuberculate inferior margin ”) and maxilla 2 (“ apices of maxilla 2 spinose ”). Barnard & Karaman (1991) adhered to the characteristics diagnostic of Karaman & Barnard (1979). Bousfield & Hendrycks (1995) expanded the diagnosis of the genus Dactylopleustes. New main features are: the shape of body, the structure of antenna 1 and 2, mouthparts, gnathopods, pereopods and pleopods. Bousfield & Hendrycks (1995) mentioned two subgeneric names within the genus Dactylopleustes in their key. These were Apodactylopleustes 1 and Neodactylopleustes, not described in a orinary and formal manner. The two subgeneric names are new to science, and seem to be available, because only one species ascribed to the respective subgenus (monotypy) in their key. Thus the genus Dactylopleustes contains 3 subgenera: Apodactylopleustes Bousfield & Hendrycks, 1995 (type species = D. obsolescens Hirayama, 1988, by monotypy), Neodactylopleustes Bousfield & Hendrycks, 1995 (type species = D. echinoides Bousfield & Hendrycks, 1995, by monotypy), and nominal subgenus Dactylopleustes Karaman & Barnard, 1979 (type species = Parapleustes echinoicus Tzvetkova, 1975, by original designation). The basis for the identification of subgenera was the ratio of the sizes of eyes, segments of the mandibular palp, coxal plates 1 and 2, telson, uropods 1 and 2, and the armament of the outer plate of maxilla 1. Tomikawa et al. (2004) described D. yoshimurai sp. nov. and provided a new key to all species, but did not adopted the subgenera proposed by Bousfield & Hendrycks (1995).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	description	Figures 1 e, 2 f, o, 3 h, q, 4 f, o, 5 f, o, 6 i, j, 7 j, k, 8 d, k, 9 – 13, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	materials_examined	Type material. Holotype: female, 5.05 mm, Х 54598 / Cr- 2456, Pacific Ocean, shelf of the eastern Kamchatka Peninsula, Avacha Bay, Vilyuchinskaya Bay (52 ° 37 ' 007 " N 158 ° 27 ' 026 " E, 7 m), stones with shells, on Strongylocentrotus polyacanthus A. Agassiz & H. L. Clark, 1907, 17 October 2022, collector D. D. Danilin. Paratypes: 1 female, 3.7 mm, Х 54599 / Cr- 2457, Pacific Ocean, shelf of the eastern Kamchatka Peninsula, Avacha Bay, Vilyuchinskaya Bay (52 ° 36 ' 52 " N 158 ° 29 ' 46 " E, 10.5 m), stones with shells, on S. polyacanthus, 21 April 2022, collector D. D. Danilin. Paratypes: 4 females, Х 54600 / Cr- 2458, with the same data as paratype Х 54599 / Cr- 2457.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	diagnosis	Diagnosis. Rostrum small, as long as lateral head lobe, lateral head lobe with rectangular anterior corner. Eye large, deep, reniform, black in alcohol. Antenna 1 about as long as antenna 2, accessory flagellum minute, one-articulate; flagellum with 5 – 6 articles. Antenna 2: flagellum with 4 – 5 articles. Upper lip: medial notch shallow. Mandible: palp article 2 with setae, as long as article 3, accessory spine row with 11 slender blades on right and 6 on left. Maxilla 1: outer plate with 17 rigid setae. Maxilla 2: outer plate with 11 stout spine-like setae. Maxilliped: inner plate with 2 small button-shaped apical setae (spines), outer plate with 2 heavy and 1 small apical setae, palp article 3 long and narrow. Pereopod 1 (gnathopod 1): propodus with 3 groups of long setae along posterior margin. Pereopod 2 (gnathopod 2): basis with setae sparsely scattered along anterior margin, propodus with 3 groups of long setae along posterior margin. Pereopods 3 and 4: basis with setae sparsely scattered along distal part of anterior margin. Pereopods 5 – 7: posterodistal lobe of basis rounded. Dactylus of pereopods 3 – 7 short, stout, inner margin finely crenulate. Pleopod 1 and 2: outer ramus with 11 articles. Uropod 1: outer ramus slightly shorter than inner ramus. Telson 1.6 times as long as wide.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	description	Description. Female (5.05 mm). Body colourless in alcohol. Pereonites, pleonites, and urosomites dorsally smooth. Head: length (excluding rostrum) exceeding pereonite 1; eye large, reniform; rostrum blunt, long, reaching about 0.5 times of antenna 1 peduncular article 1; lateral head lobe rectangular. Antenna 1 short, pediform; length ratio of peduncular articles 1 – 3 as 1.00: 0.44: 0.21; flagellum short, 0.66 times as long as peduncle, articles 1 – 3 with 1 aesthetasc for each. Antenna 2: peduncular article 5 slightly shorter than article 4, articles 1 – 3 combined shorter than article 4; article 2 with long posterodistal protrusion, subequal to article 3 length. Upper lip apically bilobate and slightly asymmetrical, without setae. Mandible: molar tuberculate, smooth; incisor with 7 – 8 teeth; left lacinia 6 - dentate, right lacinia absent; palp large, length ratio of articles 1 – 3 as 1.0: 2.8: 2.7; inner margin of palp article 3 lined with 4 strong pectinate D-setae, apex with 1 long and 3 short E-setae, A-seta absent; article 2 with 4 plumose setae along distal half of inner margin; article 1 without setae. Maxilla 1: inner plate with single plumose apical seta; apex of palp obliquely rounded, with row of 5 spine-like setae (Watling 1989: type IIA 3). Maxilla 2: inner plate slightly shorter and broader than outer plate; inner margin distally with single strong plumose seta. Maxilliped: inner plate short, reaching proximal margin of palp article 1, apex truncate, distally with 3 short setae and 2 button-shaped setae; outer plate short, exceeding palp article 1, outer margin rounded, inner margin with submarginal row of short simple setae sparsely scattered along margin; palp narrow, length ratio of articles 1 – 4 as 1.0: 1.1: 1.2: 1.2, inner margin of article 3 with a few setae and numerous setules; article 4 slender, with dense row of setules along inner margin. Coxal plates 1 – 4 increasing in depth from 1 to 3, coxal plate 4 as deep as plate 3. Coxal plate 1 with subparallel anterior and posterior margins, with rounded ventral margin, posteroventrally with 2 – 3 small teeth. Coxal plates 2 – 3 deep, ventral margins subrounded, plate 2 posteroventrally with 2 – 3 small teeth, plate 3 posteroventrally with 3 small teeth; coxal plate 4 broader, deeply excavate posteroproximally; coxae 5 – 7 posterolobate, coxa 5, anterior margin rounded, bare, posterior lobe with fine setae; coxa 6 with a few setae along anterior margin and with fine setae along posterior margin; coxa 7 with fine setae along posterior margin. Coxal gills on pereopods 2 – 6, medium in size, sac-like, with thin marginal filaments. Brood plates on pereopods 2 – 5, large in pereopod 4, leaf-shaped. Pereopod 1 (gnathopod 1): basis, anterior margin setose, posterior margin weakly expanded, with setae sparsely scattered along margin; ischium short, with posterodistal seta; merus, distal margin with row of setae; carpus, 2.1 times as long as wide, with 2 setae along anterior margin, posterior margin densely setose; propodus narrowly subrectangular, 0.84 times as long as carpus, 2.5 times as long as wide, posterior margin with 2 spine-like setae near palmar angle, palm slightly oblique; dactylus stout, overhanging palm, 0.45 times as long as propodus. Pereopod 2 (gnathopod 2): basis with setae sparsely scattered along anterior margin; ischium short, with posterodistal seta; merus, distal margin with row of setae, posterior margin with group of 2 setae midway; carpus long, 2.5 times as long as wide, posterior and distal margins densely setose, distal margin with 2 strong plumose setae; propodus narrowly subrectangular, 0.87 times as long as carpus, 2.4 times as long as wide, posterior margin with 2 spine-like setae near palmar angle, palm slightly oblique; dactylus stout, overhanging palm, 0.43 times as long as propodus. Pereopods 3 – 4 similar, length ratio from basis to dactylus 1.00: 0.28: 0.66: 0.45: 0.60: 0.24; basis linear, with setae sparsely scattered along distal part of anterior margin; merus anterodistally produced to 1 / 3 of carpus length, acute; posterior margin of carpus with 9 – 10 short spine-like setae; posterior margin of propodus with 16 (pereopod 3) — 22 (pereopod 4) short spine-like setae; dactylus stout, 0.35 – 0.40 times as long as propodus. Pereopods 5 – 7 closely homopodous, length ratio from basis to dactylus 1.00: 0.25: 0.74: 0.48: 0.69: 0.32; basis, posterior lobe rounded and minutely serrated; merus posterodistally produced to 1 / 3 – 2 / 5 of carpus length, acute, anterior margin with 6 – 9 short spine-like setae; carpus, anterior margin with 7 – 11 short spine-like setae; propodus 4.1 times as long as wide, anterior margin with 15 (pereopod 5), 17 (pereopod 6) and 17 (pereopod 7) short spine-like setae; dactylus stout. Epimeral plates 1 – 3, ventral margin with short spine-like setae, posteroventral corners subacute, posterior margins without serration. Pleopods regular, basal article of inner ramus with 3 stout two-pointed plumose setae (coupling setae) along inner margin; outer ramus with 11 (pleopods 1 and 2) and 10 (pleopod 3) articles, inner ramus with 10 (pleopods 1 and 2) and 8 – 9 (pleopod 3) articles. Uropod 1: peduncle 1.33 times as long as inner ramus; outer ramus 0.9 times as long as inner ramus; margins of peduncle and rami with serially-arranged numerous short spine-like setae. Uropod 2: inner ramus 1.1 times as long as peduncle, outer ramus 0.8 times as long as inner. Uropod 3: inner ramus 1.9 times as long as peduncle, with row of 5 – 6 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex; outer ramus about 0.6 times as long as inner, with 2 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex. Telson linguiform, with ventral keel, dorsal surface with 2 setae in distal half and 4 penicillate setae in proximal half, lateral margins parallel. Marsupium contained 2 juveniles of 1.1 mm length. Male unknown.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	materials_examined	Type locality. Pacific Ocean, shelf of the eastern Kamchatka Peninsula, Avacha Bay, Vilyuchinskaya Bay (52 ° 37 ' 007 " N 158 ° 27 ' 026 " E, 7 m).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	etymology	Etymology. Named after the type locality in Avacha Bay.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	biology_ecology	Ecology. Dactylopleustes awatschensis sp. nov. was found in the depths of 7 – 10.5 m on stones with shells, commensal on sea urchin Strongylocentrotus polyacanthus. Females with juveniles in marsupium were found in October.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	distribution	Distribution. Known only from the type locality.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFB1FFAA31FDE7A5FAD1FCAA.taxon	discussion	Remarks. Dactylopleustes awatschensis sp. nov. is morphologically close to the group of species with short, pediform antennae 1 and 2: D. echinoicus, D. echinoides, D. obsolescens, D. okhotensis sp. nov. and D. ornatus sp. nov. Dactylopleustes awatschensis sp. nov. differs from D. echinoides by the poorly setose bases of gnathopod 2 and pereopods 3 – 4 (strongly setose anteriorly in D. echinoides). From D. obsolescens the new species differs by the mandibular palp article 3 shorter than articles 1 and 2 together (longer in D. obsolescens), the propodus of gnathopod 2 with 3 groups of long setae along posterior margin (2 groups in D. obsolescens). From D. okhotensis sp. nov. and D. ornatus sp. nov. the new species differs by the apex of maxilliped outer plate with 2 heavy and 1 small apical setae (1 heavy and 1 small apical setae in D. ornatus sp. nov.), and by the propodus of gnathopod with 3 groups of long setae along posterior margin (2 groups in other species). Dactylopleustes awatschensis sp. nov. differs from D. echinoicus by the antenna 1 flagellum with 6 or fewer articles (8 articles in D. echinoicus) and by the mandibular palp article 3 subequal to article 2 in length (2 times as long as article 2 in D. echinoicus).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFAA31FDE189FAAEFB00.taxon	description	Figures 2 d, m, 3 f, o, 4 d, m, 5 d, m, 6 g, 7 g, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFAA31FDE189FAAEFB00.taxon	distribution	Distribution. Northern Pacific: Commander Islands, Bering Island, coastal shallow water, rocky reef, commensal on sea urchin Strongylocentrotus polyacanthus (Tzvetkova 1975; Dzhurinskyi 2013). Absent in my collections.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFAA31FDE76EFBB2F922.taxon	description	Figures 1 g, 2 h, q, 3 g, p, 4 e, n, 5 e, n, 6 h, 7 h, i, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFAA31FDE76EFBB2F922.taxon	distribution	Distribution. Northeastern Pacific: Vancouver Island, British Columbia, and the San Juan Channel, Washington, USA, in the depth range of 0 – 91 m, commensal on sea urchin Strongylocentrotus droebachiensis (O. F. Müller, 1776) (Bousfield & Hendrycks 1995; Tomikawa et al. 2004). Absent in my collections.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	description	Figures 1 a, 2 a, j, 3 a, b, l, 4 a, j, 5 a, j, 6 a, b, 7 a, b, 8 a, h, 14 – 18, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	materials_examined	Type material. Holotype: male, 6.6 mm, Х 54606 / Cr- 2464, Sea of Japan, Strait of Tartary, shelf of western Sakhalin (47 ° 02 ' 50 " N 142 ° 02 ' 35 " E, 10 m), rocks, on Strongylocentrotus intermedius (A. Agassiz, 1864), 01 March 2022, collector A. V. Ushakov.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	diagnosis	Diagnosis. Rostrum small, as long as lateral head lobe, lateral head lobe with acute corner. Eye large, deep, reniform, black in alcohol. Antenna 1 about as long as antenna 2, accessory flagellum minute, one-articulate; flagellum long, with 18 articles. Antenna 2: flagellum with 14 articles. Lower lip: outer lobes horizontal. Mandible: palp article 2 with setae, palp article 3 1.36 times as long as article 2, accessory spine row with 27 slender blades on right and 26 on left. Maxilla 1: outer plate with 30 rigid setae. Maxilla 2: outer plate with 14 stout spine-like setae. Maxilliped: inner plate with 6 small button-shaped apical setae (spines), outer plate with 3 heavy apical setae, palp article 3 long and narrow. Pereopod 1 (gnathopod 1): propodus with 3 groups of long setae along posterior margin. Pereopod 2 (gnathopod 2): anterior margin of basis setose, propodus with 5 groups of long setae along posterior margin. Pereopods 3 and 4: anterior margin of basis densely setose. Pereopods 5 – 7: posterodistal lobe of basis roundly truncate. Dactylus of pereopods 3 – 7 short, inner margin finely crenulate. Pleopods 1 and 2: outer ramus with 14 – 16 articles. Uropod 1: outer ramus slightly shorter than inner ramus. Telson 1.3 times as long as wide.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	description	Description. Male (6.6 mm). Body colourless in alcohol. Pereonites, pleonites, and urosomites dorsally smooth. Head: length (excluding rostrum) exceeding pereonites 1 and 2 together; eye large, reniform; rostrum acute, long, reaching about 1 / 3 length of antenna 1 peduncular article 1; lateral head lobe acute. Antenna 1 long, not pediform; length ratio of peduncular articles 1 – 3 as 1.00: 0.57: 0.24; flagellum long, 1.13 times as long as peduncle, articles 1, 2, 3, 4, 6, 8, 10 with a few aesthetascs for each. Antenna 2: peduncular article 5 slightly shorter than article 4, articles 1 – 3 combined shorter than article 4; article 4 with short posterodistal cusp. Upper lip: unknown. Lower lip: outer lobes horizontal. Mandible: molar weakly tuberculate, smooth; incisor with 9 teeth; left lacinia 9 - dentate, right lacinia absent; palp large, length ratio of articles 1 – 3 as 1.0: 2.5: 3.4; inner margin of palp article 3 lined with 8 strong pectinate D-setae, apex with 3 long and 1 short E-setae, A-seta absent, medial surface covered with numerous setules; article 2 with 8 setae along distal half of inner margin; article 1 without setae. Maxilla 1: inner plate with single club-shaped plumose apical seta; apex of palp obliquely rounded, with row of 8 spine-like setae (Watling 1989: type IIA 3). Maxilla 2: inner plate subequal in length to and broader than outer plate; inner margin in the middle with single strong plumose seta. Maxilliped: inner plate short, not reaching proximal margin of palp article 1, apex subrounded, with 3 short setae and 6 button-shaped setae; outer plate short, reaching about 2 / 3 length of palp article 2, apex truncate, outer margin rounded, inner margin with submarginal row of short simple setae sparsely scattered along margin; palp narrow, length ratio of articles 1 – 4 as 1.0: 1.1: 1.3: 1.3, inner margin of article 3 with numerous setae and covered with submarginal field of numerous setules; article 4 slender, slightly curved inside, with dense row of setules along inner margin. Coxal plates 1 – 4 increasing in depth from 1 to 4. Coxal plate 1 slightly expanding distally, with rounded ventral margin, posteroventrally with 3 – 4 small teeth. Coxal plates 2 – 3 deep, ventral margins subrounded, posteroventrally with 3 small teeth; coxal plate 4 broader, deeply excavate in proximal 1 / 3 posteriorly; coxae 5 – 7 posterolobate, coxa 5, anterior margin rounded, bare, posterior lobe with fine setae; coxa 6 with a few setae along anterior margin and with fine setae along posterior margin; coxa 7 with fine setae along posterior margin. Coxal gills on pereopods 2 – 6, medium in size, largest in pereopod 4, sac-like. Pereopod 1 (gnathopod 1): basis, anterior margin setose, posterior margin weakly expanded, with row of setae; ischium short, with posterodistal seta; merus, distal margin with row of setae, posterior margin with 3 groups of setae; carpus 2.2 times as long as wide, with 2 setae along anterior margin, posterior margin with 2 – 3 groups of plumose setae, with dense row of plumose setae and with 2 stout comb setae posterodistally, medial surface with 3 transverse groups of setae along posterior margin; propodus slightly narrowed distally, 0.92 times as long as carpus, 2.2 times as long as wide, posterior margin with 4 spine-like setae near palmar angle, medial surface with 3 transverse groups of setae along anterior margin, palm oblique, roundly passing to posterior margin; dactylus subequal to palm in length, 0.4 times as long as propodus. Pereopod 2 (gnathopod 2): basis, anterior and posterior margins setose; ischium short, with posterodistal seta; merus with row of simple setae sparsely scattered along distal margin, with 2 groups of long setae along posterior margin; carpus long and narrow, 2.7 times as long as wide, posterior margin with 4 groups of long setae, posterodistally with dense row of long setae and 2 stout comb setae; propodus slightly narrowed distally, 0.8 times as long as carpus, 2.5 times as long as wide, posterior margin with 4 spine-like setae near palmar angle, medial surface with 3 groups of setae along anterior margin and with row of 4 short setae parallel to posterior margin, palm oblique, roundly passing to posterior margin; dactylus short, slightly overhanging palm, 0.38 times as long as propodus. Pereopods 3 – 4 similar, length ratio from basis to dactylus 1.00: 0.34: 0.70: 0.49: 0.67: 0.25; basis sublinear, anterior and posterior margins densely setose; merus anterodistally produced to 1 / 4 of carpus length; posterior margin of carpus with 12 (pereopod 3) and 21 (pereopod 4) short spine-like setae; posterior margin of propodus with 23 (pereopod 3) — 24 (pereopod 4) short spine-like setae; dactylus medium wide, 0.36 – 0.39 times as long as propodus. Pereopods 5 – 7 closely homopodous, length ratio from basis to dactylus 1.00: 0.24: 0.68 – 0.80: 0.50 – 0.58: 0.75: 0.30; basis posterodistally truncate; merus posterodistally produced to 2 / 5 – 1 / 2 of carpus length, acute, anterior margin with 10 – 14 short spine-like setae; carpus, anterior margin with 18 – 23 short spine-like setae; propodus 4.1 times as long as wide, anterior margin with 33 (pereopod 5) and 22 (pereopod 6) short spine-like setae; dactylus medium wide. Epimeral plates 1 – 3: ventral margin with 3 (plates 1 and 2) and 5 (plate 3) short spine-like setae, posteroventral corners acute, posterior margins without serration. Pleopods regular, basal article of inner ramus with 4 stout two-pointed plumose setae (coupling setae) along inner margin; outer ramus with 16 (pleopod 1), 14 (pleopod 2) and 13 (pleopod 3) articles, inner ramus with 13 (pleopods 1 and 2) and 12 (pleopod 3) articles. Uropod 1: peduncle about as long as inner ramus; outer ramus 0.94 times as long as inner ramus; margins of peduncle and rami with serially-arranged numerous short spine-like setae. Uropod 2: inner ramus 1.6 times as long as peduncle, outer ramus 0.8 times as long as inner. Uropod 3: inner ramus 2.4 times as long as peduncle, with row of 7 – 8 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex; outer ramus about 0.6 times as long as inner, with 4 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex. Telson linguiform, with ventral keel, dorsal surface with 2 penicillate setae in distal half and 2 oblique rows of microscopic setules in proximal half. Female unknown.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	materials_examined	Type locality. Sea of Japan, Strait of Tartary, shelf of western Sakhalin Island, (47 ° 02 ' 50 " N 142 ° 02 ' 35 " E, 10 m).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	etymology	Etymology. Named from Latin “ longum antennae ” (long antenna) according to the structural features of antenna 1 and antenna 2.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	biology_ecology	Ecology. Dactylopleustes longoantennis sp. nov. was found on rocks in the depth of 10 m, commensal on sea urchin Strongylocentrotus intermedius.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	distribution	Distribution. Known only from the type locality.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFA6FFA331FDE501FDBCFAC6.taxon	discussion	Remarks. Dactylopleustes longoantennis sp. nov. is morphologically close to the species group with long plesiomorphic antennae 1 and 2: D. tzvetkovae sp. nov. and D. yoshimurai. Dactylopleustes longoantennis sp. nov. differs from D. tzvetkovae sp. nov. and D. yoshimurai by the flagellum of antenna 1 consisting of 18 articles (11 – 12 or fewer articles in other species), and the apex of maxilliped outer plate with 3 heavy apical setae (with 1 – 2 heavy and 1 small apical setae in other species).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFFA331FDE7A5FDDFF95A.taxon	description	Figures 1 d, 2 e, n, 3 k, t, 4 i, r, 5 i, r, 6 n, 7 o, 8 g, n, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFFA331FDE7A5FDDFF95A.taxon	distribution	Distribution. Northwestern Pacific: Kyushu Island, Ariake Sea, Japan (Hirayama 1988; Bousfield & Hendrycks 1995). Absent in my collections.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	description	Figures 1 f, 2 g, p, 3 j, s, 4 h, q, 5 h, q, 6 m, 7 n, 8 f, m, 19 – 23, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	materials_examined	Type material. Holotype: male, 3.4 mm, Х 54608 / Cr- 2466, Sea of Okhotsk, shelf of the western Kamchatka Peninsula (56 ° 13 ' 34 " N 155 ° 23 ' 07 " E, 52 m), sand, 04 August 2020, collector N. V. Shalaputin.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	diagnosis	Diagnosis. Rostrum small, as long as lateral head lobe, lateral head lobe with rectangular corner. Eye large, deep, weakly reniform, black in alcohol. Antenna 1 about as long as antenna 2, accessory flagellum minute, one-articulate; flagellum with 5 – 6 articles. Antenna 2: flagellum with 4 – 5 articles. Upper lip: medial notch deep. Mandible: palp article 2 with setae, palp article 3 1.48 times as long as article 2, accessory spine row with 8 slender blades on right and 6 blades on left. Maxilla 1: outer plate with 15 rigid setae. Maxilla 2: outer plate with 6 stout spine-like setae. Maxilliped: inner plate with 3 small button-shaped apical setae (spines), outer plate with 2 heavy and 1 small apical setae, palp article 3 long and narrow. Pereopod 1 (gnathopod 1): propodus with 2 groups of long setae along posterior margin. Pereopod 2 (gnathopod 2): basis with setae sparsely scattered along anterior margin, propodus with 3 groups of long setae along posterior margin. Pereopods 3 and 4: basis with setae sparsely scattered along anterior margin. Pereopods 5 – 7: posterodistal lobe of basis rounded. Dactylus of pereopods 3 – 7 short, stout, inner margin finely crenulate. Pleopods 1 and 2: outer ramus with 8 – 10 articles. Uropod 1: outer ramus slightly shorter than inner ramus. Telson 1.5 times as long as wide.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	description	Description. Male (3.4 mm). Body colourless in alcohol. Pereonites, pleonites, and urosomites dorsally smooth. Head: length (excluding rostrum) exceeding pereonites 1 and 2 together; eye large, weakly reniform; rostrum, blunt, long, reaching about 1 / 3 length of antenna 1 peduncular article 1; lateral head lobe rectangular. Antenna 1 short, pediform; length ratio of peduncular articles 1 – 3 as 1.00: 0.58: 0.25; flagellum short, 0.67 times as long as peduncle, articles 1 – 4 with 2 aesthetascs for each. Antenna 2: peduncular article 5 slightly shorter than article 4, articles 1 – 3 combined shorter than article 4; article 2 with long posterodistal protrusion, subequal to article 3 length. Upper lip apically bilobate and slightly asymmetrical, without setae. Lower lip: outer lobes horizontal. Mandible: molar tuberculate, smooth; incisor with 7 – 8 teeth, posterior tooth styliform; left lacinia 5 - dentate, right lacinia absent; palp large, length ratio of articles 1 – 3 as 1.0: 2.1: 3.1; inner margin of palp article 3 lined with 3 strong pectinate D-setae, apex with 4 long E-setae, A-seta absent; article 2 with 1 – 2 setae at distal half of inner margin; article 1 without setae. Maxilla 1: inner plate with single plumose apical seta; apex of palp obliquely rounded, with row of 5 – 6 spine-like setae (Watling 1989: type IIA 3). Maxilla 2: inner plate slightly longer than and as broad as outer plate; inner margin distally with single strong plumose seta. Maxilliped: inner plate short, not reaching proximal margin of palp article 1, apex subrounded, with 2 short setae and 3 button-shaped setae; outer plate short, reaching about 1 / 4 – 1 / 3 length of palp article 2, outer margin rounded, inner margin slightly concave, with 1 marginal and 2 facial short simple setae; palp narrow, length ratio of articles 1 – 4 as 1.0: 0.9: 1.3: 1.3, inner margin of article 3 with 3 setae and numerous spine-like setules; article 4 slender, finely pectinate, with dense row of setules along inner margin. Coxal plates 1 – 4 increasing in depth from 1 to 4. Coxal plate 1 with subparallel anterior and posterior margins, with rounded ventral margin, posteroventrally with 2 small teeth. Coxal plates 2 – 3 deep, ventral margins subrounded, plate 2 posteroventrally with 2 small teeth, plate 3 posteroventrally with 1 small tooth; coxal plate 4 broader, deeply excavate posteroproximally; coxae 5 – 7 posterolobate, coxa 5, anterior margin rounded, bare, posterior lobe with fine setae; coxa 6 with a few setae along anterior margin and with fine setae along posterior margin; coxa 7 with fine setae along posterior margin. Coxal gills on pereopods 2 – 6, medium in size, sac-like. Pereopod 1 (gnathopod 1): basis, anterior margin setose, posterior margin weakly expanded proximally, without setae; ischium short, with posterodistal seta; merus, distal margin with row of long setae, posterior margin with single seta midway; carpus 1.7 times as long as wide, posterior margin with 1 group of setae midway, distal margin with row of simple setae and 2 strong plumose setae; propodus slightly narrowing distally, 1.1 times as long as carpus, 2.1 times as long as wide, posterior margin with group of 1 – 2 spine-like setae near palmar angle, palm oblique; dactylus stout, subequal to palm in length, 0.33 times as long as propodus. Pereopod 2 (gnathopod 2): basis, anterior margin with single proximal seta and single anterodistal seta; ischium short, with group of 2 posterodistal setae; merus, distal margin with row of setae, posterior margin with 2 single setae; carpus long, 2.0 times as long as wide, posterior margin with 2 groups of setae, distal margin with row of simple setae and 2 strong plumose setae; propodus slightly narrowing distally, subequal in length to carpus, 2.2 times as long as wide, posterior margin with 2 single spine-like setae near palmar angle, palm oblique; dactylus stout, subequal to palm length, 0.34 times as long as propodus. Pereopods 3 – 4 similar, length ratio from basis to dactylus 1.00: 0.34: 0.63: 0.42: 0.58 – 0.69: 0.24; basis linear, with setae sparsely scattered along anterior and posterior margins; merus anterodistally produced to 1 / 5 – 1 / 4 of carpus length, acute; posterior margin of carpus with 5 – 8 short spine-like setae; posterior margin of propodus with 10 – 12 short spine-like setae; dactylus stout, 0.35 – 0.40 times as long as propodus. Pereopods 5 – 7 closely homopodous, length ratio from basis to dactylus 1.00: 0.25: 0.73: 0.48: 0.72: 0.27; basis, posterior lobe rounded; merus posterodistally produced to 1 / 2 of carpus length, acute, anterior margin with 6 – 8 short spine-like setae; carpus, anterior margin with 7 – 9 short spine-like setae; propodus 2.6 times as long as wide, anterior margin with 13 (pereopod 5), 12 (pereopod 6) and 9 (pereopod 7) short spine-like setae; dactylus stout, 0.35 – 0.39 times as long as propodus. Epimeral plates 1 – 3: ventral margins with short spine-like setae, posteroventral corners with short blunt protrusion, posterior margins with single minute seta, without serration. Pleopods regular, basal article of inner ramus with 3 – 4 stout two-pointed plumose setae (coupling setae) along inner margin; outer ramus with 7 – 9 articles, inner ramus with 7 – 8 (pleopods 1 and 2) and 6 (pleopod 3) articles. Uropod 1: peduncle 1.2 times as long as inner ramus; outer ramus 0.9 times as long as inner ramus; margins of peduncle and rami with serially-arranged numerous short spine-like setae. Uropod 2: inner ramus 1.1 times as long as peduncle, outer ramus 0.9 times as long as inner. Uropod 3: inner ramus 2.2 times as long as peduncle, with row of 3 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex; outer ramus about 0.6 times as long as inner, with 3 small spine-like setae along lateral margin and single small spine-like seta on medial margin, with acute and non-spinose apex. Telson linguiform, with ventral keel, dorsal surface with 2 distal setules and 2 sublateral groups of 2 penicillate setae. Female unknown.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	materials_examined	Type locality. Northwest of Pacific Ocean, Sea of Okhotsk, shelf of the western Kamchatka Peninsula (56 ° 13 ' 34 " N 155 ° 23 ' 07 " E, 52 m).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	etymology	Etymology. Named after the type locality, Sea of Okhotsk.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	biology_ecology	Ecology. Dactylopleustes okhotensis sp. nov. was found on sand in the depth of 52 m in the layer of constant low temperature (- 1.2 - + 0.5 ° C). The host is unknown. This station was dominated by the flat sea urchin Echinarachnius parma (Lamarck, 1816), but a globular sea urchin Strongylocentrotus pallidus (G. O. Sars, 1872) may also have existed.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	distribution	Distribution. Known only from the type locality.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FFAFFF9831FDE4D9FBD5FD72.taxon	discussion	Remarks. Dactylopleustes okhotensis sp. nov. is morphologically close to the species group with short, pediform antennae 1 and 2: D. awatschensis sp. nov., D. echinoicus, D. echinoides, D. obsolescens and D. ornatus sp. nov. Dactylopleustes okhotensis sp. nov. differs from D. echinoides by the poorly setose bases of gnathopod 2, pereopods 3 and 4 (strongly setose anteriorly in D. echinoides). From D. obsolescens the new species differs by the mandibular palp article 3 shorter than articles 1 and 2 together (longer in D. obsolescens), the oblique palmar margins of gnathopods 1 and 2 (transverse in D. obsolescens), and the propodus of gnathopod 2 with 3 groups of long setae along posterior margin (2 groups in D. obsolescens). Dactylopleustes okhotensis sp. nov. differs from D. awatschensis sp. nov. by the maxilla 2 outer plate with 6 stout spine-like apical setae (8 – 11 spine-like setae in D. awatschensis sp. nov.), and the gnathopod 1 propodus with 2 groups of long setae along posterior margin (with 3 groups of long setae along posterior margin in other species). From D. ornatus sp. nov. the new species differs by maxilla 2 outer plate with 6 stout spine-like apical setae (7 – 9 in D. ornatus sp. nov.), the apex of maxilliped outer plate with 2 heavy and 1 small apical setae (1 heavy and 1 small apical setae in D. ornatus sp. nov.), and the long and narrow palp article 3 of maxilliped (short and stout in D. ornatus sp. nov.).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	description	Figures 1 h, 2 i, r, 3 i, r, 4 g, p, 5 g, p, 6 k, l, 7 l, m, 8 e, l, 24 – 30, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	materials_examined	Type material. Holotype: female, 3.1 mm, Х 54601 / Cr- 2459, Sea of Okhotsk, Sakhalin, Aniva Bay (46 ° 36 ' 35 " N 142 ° 59 ' 57 " E, littoral), rock, on Strongylocentrotus intermedius, 28 July 2021, collector S. V. Labay. Paratypes: 1 female, 2.9 mm, Х 54602 / Cr- 2460, with same data as the holotype; paratypes: 16 females, Х 54603 / Cr- 2461, with same data as the holotype. Addition material. 1 female, 2.6 mm, Х 54604 / Cr- 2462, Sea of Japan, Strait of Tartary, shelf of western Sakhalin Island, (47 ° 02 ' 55 " N 142 ° 02 ' 49 " E, 4 m), coarse sand, on S. intermedius, 09 September 2021, collector A. V. Ushakov; 2 females, Х 54605 / Cr- 2463, with same data as Х 54604 / Cr- 2462.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	diagnosis	Diagnosis. Rostrum small, as long as lateral head lobe, lateral head lobe with subrectangular corner. Eye large, deep, suboval, white when alive, black in alcohol. Antenna 1 about as long as antenna 2, accessory flagellum minute, one-articulate; flagellum with 5 – 6 articles. Antenna 2: flagellum with 5 articles. Upper lip: medial notch shallow. Mandible: palp article 2 with setae, palp article 3 1.27 times as long as article 2, accessory spine row with 12 slender blades on right and 8 slender blades on left. Maxilla 1: outer plate with 16 rigid setae. Maxilla 2: outer plate with 7 – 9 stout spine-like setae. Maxilliped: inner plate with 3 small button-shaped apical setae (spines), outer plate with 1 heavy and 1 small apical setae, palp article 3 short and wide, expanded medially. Pereopod 1 (gnathopod 1): propodus with 2 groups of long setae along posterior margin. Pereopod 2 (gnathopod 2): basis with setae sparsely scattered along anterior margin, propodus with 3 groups of long setae along posterior margin. Pereopods 3 and 4: basis with setae sparsely scattered along anterior margin. Pereopods 5 – 7: posterodistal lobe of basis roundly truncate. Dactylus of pereopods 3 – 7 short, stout, inner margin finely crenulate. Pleopods 1 and 2: outer ramus with 9 – 10 articles. Uropod 1: outer ramus slightly shorter than inner ramus. Telson 1.5 times as long as wide.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	description	Description. Female (3.1 mm). Brightly coloured when alive. Head and pereonites 1 – 5 with a transverse brown stripe for each. Coxal plates 1 – 3 with 2 submarginal brown stripes looped ventrally. Coxal plate 4 with 3 stripes. Pereonites 6, 7, pleonites, urosomites, pereopods 5 – 7 and uropods with blurred brown pattern. Flagella of antennae 1 and 2 with a red band at the middle and with red tip. Body colourless in alcohol. Pereonites, pleonites, and urosomites dorsally smooth. Head: length exceeding pereonites 1 and 2 together; eye large, suboval; rostrum blunt, high, reaching about 0.5 times of antenna 1 peduncular article 1; lateral head lobe subrectangular. Antenna 1 short, pediform; length ratio of peduncular articles 1 – 3 as 1.00: 0.53: 0.22; flagellum short, 0.74 times as long as peduncle, articles 1, 3, 5, 6 with 1 – 2 aesthetascs for each. Antenna 2: peduncular articles 5 subequal to article 4 in length, articles 1 – 3 combined shorter than article 4. Upper lip: apically bilobate, without setae. Lower lip: outer lobes horizontal. Mandible: molar tuberculate, smooth; incisor with 7 – 8 teeth, posterior tooth styliform; left lacinia 6 - dentate, right lacinia absent; palp large, length ratio of articles 1 – 3 as 1.0: 1.7: 2.6; inner margin of palp article 3 lined with 4 strong pectinate D-setae, apex with 3 long and 1 short E-setae, A-seta absent; article 2 with 2 setae at distal half of inner margin; article 1 without setae. Maxilla 1: inner plate with single plumose apical seta; apex of palp obliquely rounded, with row of 4 spine-like setae (Watling 1989: type IIA 3). Maxilla 2: inner plate slightly shorter than outer plate; inner margin distally with single strong plumose seta. Maxilliped: inner plate short, not reaching proximal margin of palp article 1, apex subrounded, with 2 short setae and 3 button-shaped setae; outer plate short, reaching about 1 / 2 length of palp article 2, apex rounded, inner margin with submarginal row of 4 short simple setae; palp, length ratio of articles 1 – 4 as 1.0: 1.1: 1.1: 1.3, inner margin of article 3 with 6 setae and numerous setules; article 4 slender, with dense row of setules along inner margin. Coxal plates 1 – 4 increasing in depth from 1 to 4. Coxal plate 1 slightly expanded ventrally, with rounded ventral margin, posteroventrally with 2 – 3 small teeth. Coxal plates 2 – 3 deep, ventral margins rounded, posteroventrally with 2 small teeth for each; coxal plate 4 deeply excavate posteroproximally; coxae 5 – 6 posterolobate, coxa 5, anterior margin rounded, bare, posterior lobe without fine setae; coxa 6 bare or with a few setae along anterior margin, without fine setae on posterior margin; coxa 7 roundly rectangular, with a few fine setae ventrally. Coxal gills on pereopods 2 – 6, medium in size, sac-like. Pereopod 1 (gnathopod 1): basis, anterior margin with a few long setae at proximal half, posterior margin weakly expanded proximally, with sparsely scattered setae or bare; ischium short, with posterodistal seta; merus, distal margin with row of long setae, posterior margin with single seta midway; carpus 1.8 times as long as wide, posterior margin with 2 groups of plumodenticulate setae (Watling 1989: type IA 3), with distal row of plumodenticulate setae and 2 stout comb setae; propodus 0.9 times as long as carpus, 1.9 times as long as wide, anterior and posterior margins subparallel, posterior margin with group of 2 spine-like setae near palmar angle, palm slightly oblique; dactylus stout, exceeding palm, 0.44 times as long as propodus. Pereopod 2 (gnathopod 2): basis, with setae sparsely scattered along anterior margin; ischium short, with posterodistal seta; merus, distal margin with row of setae, posterior margin with seta midway; carpus long, 2.4 times as long as wide, posterior margin with 2 groups of setae, with distal row of simple setae and 1 comb seta; propodus 0.85 times as long as carpus, 2.1 times as long as wide, anterior and posterior margins subparallel, posterior margin with row of 2 spine-like setae near palmar angle, palm slightly oblique; dactylus stout, subequal to palm in length, 0.42 times as long as propodus. Pereopods 3 – 4 similar, length ratio from basis to dactylus 1.00: 0.25: 0.58: 0.42: 0.56 – 0.63: 0.25; basis linear, with setae sparsely scattered along anterior and posterior margins; merus anterodistally produced to 1 / 4 – 1 / 3 of carpus length, acute; posterior margin of carpus with 4 – 5 short spine-like setae; posterior margin of propodus with 12 – 13 short spine-like setae; dactylus stout, 0.40 – 0.45 times as long as propodus. Pereopods 5 – 7 closely homopodous, length ratio from basis to dactylus 1.00: 0.26: 0.68 – 0.86: 0.52: 0.61 – 0.73: 0.23 – 0.31; basis, posterior lobe slightly truncate; merus posterodistally produced to 3 / 5 of carpus length, acute, anterior margin with 7 – 8 short spine-like setae; carpus, anterior margin with 7 – 9 short spine-like setae; propodus 2.5 times as long as wide, anterior margin with 7 – 8 (pereopod 5), 10 (pereopod 6) and 8 – 9 (pereopod 7) short spine-like setae; dactylus stout, 0.37 – 0.44 times as long as propodus. Epimeral plates 1 – 3: ventral margin with short 1 – 2 spine-like setae, posteroventral corner with short protrusion, posterior margin with single seta (plates 1 and 2), without serration. Pleopods regular, basal article of inner ramus with 2 – 3 stout two-pointed plumose setae (coupling setae) along inner margin; outer ramus with 9 – 10 articles, inner ramus with 8 (pleopods 1 and 2) and 7 (pleopod 3) articles. Uropod 1: peduncle almost as long as inner ramus; outer ramus shorter, 0.9 times as long as inner ramus; margins of peduncle and rami with serially-arranged numerous short spine-like setae. Uropod 2: inner ramus 1.4 times as long as peduncle, outer ramus 0.7 times as long as inner. Uropod 3: inner ramus 1.9 times as long as peduncle, with row of 4 – 5 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex; outer ramus about 0.5 times as long as inner, with 1 – 2 small spine-like setae along lateral margin and 1 small spine-like seta on medial margin, with acute and non-spinose apex. Telson linguiform, with ventral keel, dorsal surface with 2 sublateral groups of 2 penicillate setae, with 2 rows of microscopic setules in proximal part. Male unknown.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	materials_examined	Type locality. Northwest of Pacific Ocean, Sea of Okhotsk, shelf of southern Sakhalin, Aniva Bay, (46 ° 36 ' 35 " N 142 ° 59 ' 57 " E, littoral).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	etymology	Etymology. Named from Latin “ ornata ” (adorned) according to colouring when alive.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	biology_ecology	Ecology. Dactylopleustes ornatus sp. nov. was found on sands, shell rock and rock in the depths of 0 – 5 m, commensal on sea urchin Strongylocentrotus intermedius.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	distribution	Distribution. Northwest of Pacific Ocean, Sea of Okhotsk, Sea of Japan, shelf of southern Sakhalin Island.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF94FF9031FDE0F1FAC2F80C.taxon	discussion	Remarks. Dactylopleustes ornatus sp. nov. is morphologically close to the species group with short, pediform antennae 1 and 2: D. awatschensis sp. nov., D. echinoicus, D. echinoides, D. obsolescens and D. ochotensis sp. nov. From D. okhotensis sp. nov., D. ornatus sp. nov. differs by the maxilla 2 outer plate with 7 – 9 stout apical spine-like setae (6 spine-like apical setae in D. okhotensis sp. nov.), the apex of maxilliped outer plate with 1 heavy and 1 small apical setae (2 heavy and 1 small setae in D. okhotensis sp. nov.), and the shorter and stout maxilliped palp article 3 (long and narrow in D. okhotensis sp. nov.). Dactylopleustes ornatus sp. nov. differs from D. awatschensis sp. nov., D. echinoicus, D. echinoides and D. obsolescens in the same set of characters as D. ochotensis sp. nov.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	description	Figures 1 b, 2 b, k, 3 c, m, 4 b, k, 5 b, k, 6 c, d, 7 c, d, 8 b, i, 31 – 35, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	materials_examined	Type material. Holotype: female, 3.6 mm, Х 54607 / Cr- 2465, Sea of Okhotsk, shelf of south-eastern Sakhalin, (47 ° 54 ' 16.35 " N 142 ° 31 ' 30.537 " E, 5 m), stones, on Strongylocentrotus intermedius, 12 October 2021, collector A. V. Ushakov.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	diagnosis	Diagnosis. Rostrum small, as long as lateral head lobe, lateral head lobe with subacute anterior corner. Eye large, deep, reniform, black in alcohol. Antenna 1 slightly longer than antenna 2, accessory flagellum minute, one-articulate; flagellum medium long, with 12 articles. Antenna 2: flagellum with 8 articles. Upper lip: medial notch shallow. Lower lip: outer lobes horizontal. Mandible: palp article 2 with setae, palp article 3 1.38 times as long as article 2, accessory spine row with 20 slender blades on right and 21 on left. Maxilla 1: outer plate with 23 rigid setae. Maxilla 2: outer plate with 8 – 11 stout spine-like setae. Maxilliped: inner plate with 5 – 6 small button-shaped apical setae (spines), outer plate with 2 heavy and 1 small apical setae, palp article 3 long and narrow. Pereopod 1 (gnathopod 1): propodus with 2 groups of long setae along posterior margin. Pereopod 2 (gnathopod 2): basis with setae sparsely scattered along anterior margin, propodus with 4 groups of long setae along posterior margin. Pereopods 3 and 4: anterior margin of basis poorly setose. Pereopods 5 – 7: posterodistal lobe of basis roundly truncate. Dactylus of pereopods 3 – 7 short, inner margin finely crenulate. Pleopods 1 and 2: outer ramus with 11 articles. Uropod 1: outer ramus slightly shorter than inner ramus. Telson 1.4 times as long as wide.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	description	Description. Female (3.6 mm). Body colourless in alcohol. Pereonites, pleonites, and urosomites dorsally smooth. Head: length (excluding rostrum) exceeding pereonites 1 and 2 together; eye large, reniform; rostrum acute, long, reaching about 0.5 length of antenna 1 peduncular article 1; lateral head lobe subacute. Antenna 1 long, not pediform; length ratio of peduncular articles 1 – 3 as 1.00: 0.52: 0.22; flagellum long, 1.05 times as long as peduncle, articles with 3 aesthetascs for each. Antenna 2: peduncular article 5 slightly shorter than article 4, articles 1 – 3 combined as long as article 4. Mandible: molar tuberculate, smooth; incisor with 6 – 7 teeth; left lacinia 7 - dentate, right lacinia absent; palp large, length ratio of articles 1 – 3 as 1.0: 3.0: 4.1; inner margin of palp article 3 lined with 6 strong pectinate D-setae, apex with 3 short and 1 long E-setae, A-seta absent, medial surface with field of numerous setules; article 2 with 5 setae along distal half of inner margin; article 1 without setae. Maxilla 1: inner plate with single strong plumose apical seta; apex of palp rounded, with row of 6 spine-like setae (Watling 1989: type IIA 3). Maxilla 2: inner plate shorter than outer plate; inner margin distally with single strong plumose seta. Maxilliped: inner plate short, not reaching proximal margin of palp article 1, apex obliquely truncate, with 2 short setae and 5 – 6 button-shaped setae; outer plate short, reaching about 1 / 2 – 2 / 3 length of palp article 2, outer margin rounded, inner margin slightly concave, with submarginal row of sparsely scattered short simple setae; palp narrow, length ratio of articles 1 – 4 as 1.0: 1.0: 1.3: 1.5, inner margin of article 3 with 7 setae and submarginal field of numerous small spine-like setules; article 4 slender, slightly curved inside, with dense row of small spine-like setules along inner margin. Coxal plates 1 – 4 increasing in depth from 1 to 4. Coxal plate 1 slightly expanding distally, with rounded ventral margin, posteroventrally with 3 small teeth. Coxal plates 2 – 3 deep, ventral margins subrounded, posteroventrally with 2 – 3 small teeth for each; coxal plate 4 broader, deeply excavated in proximal 1 / 3 posteriorly; coxae 5 – 7 posterolobate, coxa 5, anterior margin rounded, bare, posterior lobe with single fine seta ventrally; coxa 6 with a few setae along anterior margin and with single fine seta on posterior lobe ventrally; coxa 7 with fine setae along posterior margin. Coxal gills on pereopods 2 – 6, medium in size, large in pereopod 4, sac-like. Pereopod 1 (gnathopod 1): basis, anterior and posterior margins setose, posterior margin weakly expanded; ischium short, with 1 – 2 posterodistal setae; merus, distal margin with row of setae, with 3 strong setae along posterior margin; carpus 2.2 times as long as wide, with 2 setae along anterior margin, posterior margin with 3 groups of plumose setae, with dense row of plumose setae and 2 stout comb setae posterodistally, medial surface with 3 transverse groups of 2 – 3 setae along posterior margin; propodus with subparallel margins, 0.86 times as long as carpus, 2.3 times as long as wide, posterior margin with 2 spine-like setae near palmar angle, medial surface with oblique row of 3 setae, palm oblique, roundly passing to posterior margin; dactylus slightly longer than palm, 0.4 times as long as propodus. Pereopod 2 (gnathopod 2): basis, anterior and posterior margins poorly setose; ischium short, with 1 – 2 posterodistal setae; merus, distal margin with row of sparsely scattered setae, with 2 long setae along posterior margin; carpus long and narrow, 2.6 times as long as wide, posterior margin with 3 – 4 groups of long setae, with dense row of long setae and single stout comb seta posterodistally; propodus slightly narrowed distally, 0.9 times as long as carpus, 2.7 times as long as wide, posterior margin with 4 – 5 spine-like setae near palmar angle, palm strongly oblique, roundly passing to posterior margin; dactylus short, shorter than palmar margin, 0.33 times as long as propodus. Pereopods 3 – 4 similar, length ratio from basis to dactylus 1.00: 0.22: 0.68: 0.48: 0.67: 0.29; basis sublinear, anterior and posterior margins setose; merus anterodistally produced to 1 / 4 of carpus length; posterior margin of carpus with 7 – 8 short spine-like setae; posterior margin of propodus with 14 – 15 short spine-like setae; dactylus stout, 0.43 – 0.45 times as long as propodus. Pereopods 5 – 7 closely homopodous, length ratio from basis to dactylus 1.00: 0.29: 0.70 – 0.92: 0.48 – 0.54: 0.70 – 0.82: 0.31 – 0.41; basis, posterodistally lobe roundly truncate; merus posterodistally produced to 2 / 5 – 1 / 2 of carpus length, anterior margin with 6 – 11 short spine-like setae; carpus, anterior margin with 7 – 9 short spine-like setae; propodus 3.0 times as long as wide, anterior margin with 14 short spine-like setae; dactylus stout, 0.44 – 0.49 times as long as propodus. Epimeral plates 1 – 3: ventral margin with 1 (plate 1), 4 (plate 2) and 3 (plate 3) short spine-like setae, posteroventral corner subacute, posterior margin without serration. Pleopods regular, basal article of inner ramus with 3 stout two-pointed plumose setae (coupling setae) along inner margin; outer ramus with 11 (pleopod 1), 11 (pleopod 2) and 9 (pleopod 3) articles, inner ramus with 10 (pleopod 1), 9 (pleopod 2) and 8 (pleopod 3) articles. Uropod 1: peduncle 0.94 times as long as inner ramus; outer ramus 0.89 times as long as inner ramus; margins of peduncle and rami with serially-arranged numerous short spine-like setae. Uropod 2: inner ramus 1.4 times as long as peduncle, outer ramus 0.73 times as long as inner. Uropod 3: inner ramus 2.0 times as long as peduncle, with row of 5 – 6 small spine-like setae along lateral and medial margins for each, with acute and non-spinose apex; outer ramus about 0.6 times as long as inner, with 4 small spine-like setae along lateral margin and single seta on medial margin, with acute and non-spinose apex. Telson linguiform, with ventral keel, dorsal surface with 2 groups of 2 penicillate setae and with 2 short setae. Male unknown.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	materials_examined	Type locality. Sea of Okhotsk, shelf of south-eastern Sakhalin Island, (47 ° 54 ' 16.35 " N 142 ° 31 ' 30.537 " E, 5 m).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	etymology	Etymology. Named in memory of famous Russian carcinologist Nina L. Tzvetkova.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	biology_ecology	Ecology. Dactylopleustes tzvetkovae sp. nov. was found on stones in the depth of 5 m, commensal on sea urchin Strongylocentrotus intermedius.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	distribution	Distribution. Known only from the type locality.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF9FFF8931FDE2B0FC82FAA2.taxon	discussion	Remarks. Dactylopleustes tzvetkovae sp. nov. is morphologically close to the species group with plesiomorphic long antennae 1 and 2: D. longoantennis sp. nov. and D. yoshimurai. Dactylopleustes tzvetkovae sp. nov. differs from D. longoantennis sp. nov. by the flagellum of antenna 1 and 2 consisting of 12 and 8 articles respectively (17 and 14 in D. longoantennis sp. nov.), the apex of maxilliped outer plate with 2 heavy and 1 small apical setae (3 heavy setae in D. longoantennis sp. nov.), the posterior margin of propodus of gnathopods 1 and 2 with 2 and 4 groups of setae respectively (3 and 5 in D. longoantennis sp. nov.). Dactylopleustes tzvetkovae sp. nov. differs from D. yoshimurai by the flagellum of antenna 1 consisting of 12 articles (8 in D. yoshimurai), the apex of maxilliped outer plate with 2 heavy and 1 small apical setae (1 heavy and 1 small setae in D. yoshimurai), and the maxilla 1 outer plate with 23 rigid apical setae (17 – 18 in D. yoshimurai).	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF85FF8931FDE781FD98F964.taxon	description	Figures 1 c, 2 c, l, 3 d, e, n, 4 c, l, 5 c, l, 6 e, f, 7 e, f, 8 c, j, 36	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
03CB87F1FF85FF8931FDE781FD98F964.taxon	distribution	Distribution. Northwestern Pacific: Hokkaido Island, shallow waters, on Strongylocentrotus intermedius (Tomikawa et al. 2004). Absent in my collections.	en	Labay, Vjacheslav S. (2025): Review of amphipods of the family Pleustidae Buchholz, 1874 (Amphipoda) from the coastal waters of Sakhalin Island and Kamchatka Peninsula (Far East of Russia). IV. Subfamily Dactylopleustinae Bousfield and Hendrycks, 1994. Zootaxa 5627 (2): 201-253, DOI: 10.11646/zootaxa.5627.2.1, URL: https://doi.org/10.11646/zootaxa.5627.2.1
