Antarctodius Berge, Vader & Coleman 1999

• Main Author: Ariyama, Hiroyuki
• Format: Text
• Language: unknown
• Published: Zenodo 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Malacostraca; Amphipoda; Ochlesidae; Antarctodius; Antarctodius japonicus; Antarctic; Southern Ocean; The Antarctic; Okhotsk; Antarctic Ocean; Coleman; Seta; McIntyre; Antarc*; antarcticus; okhotsk sea
• Online Access: https://dx.doi.org/10.5281/zenodo.5700477; https://zenodo.org/record/5700477

Genus Antarctodius Berge, Vader & Coleman, 1999 [Japanese name: Mukashi-subeyokoebi-zoku] Antarctodius Berge, Vader & Coleman, 1999: 244; Labay, 2010: 35. Type species. Odius antarcticus Watling & Holman, 1981. Diagnosis [emended from Ariyama (2011)]. Body, anterodorsal margin of pereonite 1 not produced; dorsal projections of pereonites absent, those of pleonites present or absent; posterolateral margin of pleonite 3 with or without projection. Eyes variable. Antenna 1 , peduncle with article 2 shorter than article 1; accessory flagellum absent or present. Upper lip , tip incised asymmetrically. Mandible conical; incisor narrow; lacinia mobilis present on left side; palp somewhat distal to molar. Lower lip with outer lobes long, strongly notched inside. Maxilla 1 with inner plate bearing 3 apical plumose setae; outer plate relatively short, styliform, with many robust setae on tip; palp 2-articulated, wide, exceeding outer plate, with several apical setae. Maxilla 2 , inner plate almost same length as outer plate, mediodistal margins of both plates strongly setose. Maxilliped , inner plate narrow; outer plate medium, reaching distal end of palp article 2; palp 4-articulated, article 2 not expanded medially, article 4 short or long. Coxa 1 a little shorter than coxa 2; coxae 2–4 progressively wider, equally long. Gills present on gnathopod 2–pereopod 7(?). Oostegites of female present on gnathopod 2–pereopod 5. Gnathopod 1 , propodus not projected posterodistally, posterodistal corner with long robust seta; dactylus small, triangular, with several plumose setae. Gnathopod 2 , propodus narrow, palm weakly transverse, distal margin serrated; dactylus with accessory spine. Pereopods 3–7 , meri projected distally. Uropods , inner ramus of uropod 3 slightly wide; peduncles of uropods 1, 2 and both rami bearing many robust setae. Telson cleft or entire. Species included. Antarctodius antarcticus (Watling & Holman, 1981); A. japonicus Ariyama, 2011; A. noncarinatus Labay, 2010; and A. rauscherti Coleman & Kauffeldt, 2001. Remarks. The diagnosis of the genus is emended mainly because the presence of the accessory flagellum and the gill on the coxa 7 is confirmed in the present study. However, in the papers dealing with the other Antarctodius species, the accessory flagellum is stated to be absent and the gill is not mentioned (Watling & Holman 1981, Coleman & Kauffeldt 2001, Labay 2010). A closer examination of them is needed. Distribution. Antarctic Ocean, Okhotsk Sea and Japan. Antarctodius japonicus Ariyama, 2011 [Japanese name: Mukashi-subeyokoebi] (Figs 23, 24) Antarctodius japonicus Ariyama, 2011: 34, figs 22–25. Material examined. Female, 3.2 mm (OMNH-Ar-12245), off Jōgashima Island, Miura City, Kanagawa Prefecture, 35°07′14′′N, 139°34′24′′E, 91-95 m depth, sandy bottom, using dredge, 17 June 2013, coll. H. Kohtsuka. Material for comparison. Holotype: male, 2.9 mm (1.7 mm in a straight line) (NSMT-Cr-21285), midway between Kuchinotsu and Ohyano, Ariake Sound, 32°34′N, 130°15′E, 47 m depth, sandy gravel bottom, using Smith-McIntyre grab, 5 June 1997, coll. M. Azuma. Description of female. Based on female, 3.2 mm (OMNH-Ar-12245). Body (Fig. 23), pleonites 1–3 each lacking dorsal projection, pleonite 3 with small projection posteroventrally. Head (Figs 23, 24). Lateral cephalic lobe projected anteroventrally. Eyes 9.3% length of body. Antenna 1 stout; length ratio of peduncular articles 1–3 1:0.8:0.35; accessory flagellum present, minute, tip with 1 seta; primary flagellum with 6 articles, article 1 not elongate, each article with a few aesthetascs. Maxilla 1 small; inner plate longish pear-shaped, with 3 plumose setae on tip; medial margin of outer plate bearing 8 robust setae and many thick and fine setae, palp 2-articulated, tip heavily setose. Maxilliped , inner plate distal margin bearing 3 robust setae; outer plate truncate, slightly exceeding distal end of palp article 2, laterodistal corner with 7 robust setae; palp articles 2 and 3 setose mediodistally, article 4 long triangular, about 0.7 times length of article 3. Pereon and pleon (Fig. 24). Gnathopod 1 slender; coxa narrow; basis slightly widened proximally, anterior margin with several short setae, posterior margin bearing 6 long setae; posterodistal corner of propodus with long robust seta and 3 short setae; dactylus complexly trifurcated, exceeding tip of robust seta of propodus, bearing 2 plumose and 1 short setae. Gnathopod 2 larger than gnathopod 1; coxa almost straight, inner surface with tiny process; basis with single short seta on anterior margin; merus truncate distally, posterodistal corner with 2 robust setae; carpus produced posterodistally, with 2 anterodistal, 2 lateral, 3 posterior and 8 posterodistal robust setae; propodus short, with 2 anterior, 2 anterodistal, 5 lateral and 5 medial robust setae, palm slightly curved, with many serrations; dactylus short, posterior margin with small spine. Pereopod 7 , coxa small, unlobed, anterodistal margin with 3 short setae, gill present; basis wide, produced posterodistally, posterior margin slightly concave, anterior margin with 8 plumose and 12 robust setae, anterolateral surface and anterodistal corner bearing 5 and 1 robust setae, respectively, inner surface with many plumose (?) setae; ischium with 1 anterior and 1 anterodistal robust setae; merus with 2 anterior, 7 anteromedial, 2 anterodistal, 4 posterior and 1 posterodistal robust setae; carpus–dactylus lost. Telson deeply cleft, both tips each with minute seta. Description of male [based on holotype, male, 2.9 mm (1.7 mm in a straight line) (NSMT-Cr-21285)]. Antenna 1 with large accessary flagellum, tip with 2 setae (Fig. 24 M-AF). Pereopod 7 , coxa with damaged fragment of gill. Both overlooked in Ariyama (2011). Coloration in life. Unknown. Remarks. Ariyama (2011) described this species based on a single male specimen. The present female specimen, however, can be identified as Antarctodius japonicus , because most characters including important ones are shared with the holotype (ex. maxilla 1, maxilliped, gnathopods and telson), although there are some trifle differences. Habitat. Found on sandy gravel bottom and sandy bottom, 47–95 m depth. Distribution. Ariake Sound in Kyūshū (Ariyama 2011) and off Jōgashima Island, Miura City (present study), both in Japan. Antarctodius japonicus Ariyama, 2011 [Japanese name: Mukashi-subeyokoebi] (Figs 23, 24) Antarctodius japonicus Ariyama, 2011: 34, figs 22–25. Material examined. Female, 3.2 mm (OMNH-Ar-12245), off Jōgashima Island, Miura City, Kanagawa Prefecture, 35°07′14′′N, 139°34′24′′E, 91-95 m depth, sandy bottom, using dredge, 17 June 2013, coll. H. Kohtsuka. Material for comparison. Holotype: male, 2.9 mm (1.7 mm in a straight line) (NSMT-Cr-21285), midway between Kuchinotsu and Ohyano, Ariake Sound, 32°34′N, 130°15′E, 47 m depth, sandy gravel bottom, using Smith-McIntyre grab, 5 June 1997, coll. M. Azuma. Description of female. Based on female, 3.2 mm (OMNH-Ar-12245). Body (Fig. 23), pleonites 1–3 each lacking dorsal projection, pleonite 3 with small projection posteroventrally. Head (Figs 23, 24). Lateral cephalic lobe projected anteroventrally. Eyes 9.3% length of body. Antenna 1 stout; length ratio of peduncular articles 1–3 1:0.8:0.35; accessory flagellum present, minute, tip with 1 seta; primary flagellum with 6 articles, article 1 not elongate, each article with a few aesthetascs. Maxilla 1 small; inner plate longish pear-shaped, with 3 plumose setae on tip; medial margin of outer plate bearing 8 robust setae and many thick and fine setae, palp 2-articulated, tip heavily setose. Maxilliped , inner plate distal margin bearing 3 robust setae; outer plate truncate, slightly exceeding distal end of palp article 2, laterodistal corner with 7 robust setae; palp articles 2 and 3 setose mediodistally, article 4 long triangular, about 0.7 times length of article 3. Pereon and pleon (Fig. 24). Gnathopod 1 slender; coxa narrow; basis slightly widened proximally, anterior margin with several short setae, posterior margin bearing 6 long setae; posterodistal corner of propodus with long robust seta and 3 short setae; dactylus complexly trifurcated, exceeding tip of robust seta of propodus, bearing 2 plumose and 1 short setae. Gnathopod 2 larger than gnathopod 1; coxa almost straight, inner surface with tiny process; basis with single short seta on anterior margin; merus truncate distally, posterodistal corner with 2 robust setae; carpus produced posterodistally, with 2 anterodistal, 2 lateral, 3 posterior and 8 posterodistal robust setae; propodus short, with 2 anterior, 2 anterodistal, 5 lateral and 5 medial robust setae, palm slightly curved, with many serrations; dactylus short, posterior margin with small spine. Pereopod 7 , coxa small, unlobed, anterodistal margin with 3 short setae, gill present; basis wide, produced posterodistally, posterior margin slightly concave, anterior margin with 8 plumose and 12 robust setae, anterolateral surface and anterodistal corner bearing 5 and 1 robust setae, respectively, inner surface with many plumose (?) setae; ischium with 1 anterior and 1 anterodistal robust setae; merus with 2 anterior, 7 anteromedial, 2 anterodistal, 4 posterior and 1 posterodistal robust setae; carpus–dactylus lost. Telson deeply cleft, both tips each with minute seta. Description of male [based on holotype, male, 2.9 mm (1.7 mm in a straight line) (NSMT-Cr-21285)]. Antenna 1 with large accessary flagellum, tip with 2 setae (Fig. 24 M-AF). Pereopod 7 , coxa with damaged fragment of gill. Both overlooked in Ariyama (2011). Coloration in life. Unknown. Remarks. Ariyama (2011) described this species based on a single male specimen. The present female specimen, however, can be identified as Antarctodius japonicus , because most characters including important ones are shared with the holotype (ex. maxilla 1, maxilliped, gnathopods and telson), although there are some trifle differences. Habitat. Found on sandy gravel bottom and sandy bottom, 47–95 m depth. Distribution. Ariake Sound in Kyūshū (Ariyama 2011) and off Jōgashima Island, Miura City (present study), both in Japan. : Published as part of Ariyama, Hiroyuki, 2021, Five species of the family Odiidae (Crustacea: Amphipoda) collected from Japan with descriptions of a new genus and four new species, pp. 485-516 in Zootaxa 5067 (4) on pages 512-515, DOI: 10.11646/zootaxa.5067.4.2, http://zenodo.org/record/5683379 : {"references": ["Berge, J., Vader, W. & Coleman, O. (1999) A cladistic analysis of the amphipod families Ochlesidae and Odiidae, with description of a new species and genus. In: Schram, F. R. & von Vaupel Klein, J. C. (Eds.), Crustaceans and the Biodiversity Crisis. Brill, Leiden, pp. 239 - 265.", "Labay, V. S. (2010) A new species and subspecies of Ochlesidae Stebbing, 1910 (Amphipoda: Gammaridea) from the Okhotsk Sea. Zootaxa, 2354 (1), 35 - 44. https: // doi. org / 10.11646 / zootaxa. 2354.1.3", "Watling, L. & Holman, H. (1981) Additional acanthonotozomatid, paramphithoid, and stegocephalid Amphipoda from the Southern Ocean. Proceeding of the Biological Society of Washington, 94, 181 - 227.", "Ariyama, H. (2011) Six species of the family Odiidae (Crustacea: Amphipoda) from Japan, with descriptions of a new genus and four new species. Bulletin of the National Museum of Nature and Science, Series A (Zoology), Supplement, 5, 1 - 39.", "Coleman, C. O. & Kauffeldt, J. (2001) Antarctodius rauscherti, a new species (Crustacea: Amphipoda: Ochlesidae) from the Antarctic Ocean. Proceedings of the Biological Society of Washington, 114, 427 - 434."]}