Grandidierella osakaensis Ariyama, 1996

Ariyama, Hiroyuki & Taru, Masanori, 2017, Three Species of Grandidierella (Crustacea: Amphipoda: Aoridae) from Coastal Areas of the Tohoku and Kanto-Tokai Districts, East Japan, with the Description of Two New Species, Species Diversity 22, pp. 187-200 : 196-199

publication ID	https://doi.org/ 10.12782/sd.22_187
publication LSID	lsid:zoobank.org:pub:07D72FEB-42BC-4D79-A5A6-3F0D9C9C430A
persistent identifier	https://treatment.plazi.org/id/956A5A6E-1758-FF9C-7D81-4165FE4E3945
treatment provided by	Felipe
scientific name	Grandidierella osakaensis Ariyama, 1996
status

Treatment

Grandidierella osakaensis Ariyama, 1996 View in CoL ( Figs 2D, E View Fig , 9–11 View Fig View Fig View Fig )

[Japanese name: Ōsaka-dorosokoebi]

Grandidierella osakaensis Ariyama, 1996: 173 View in CoL , figs 6–10; Ariyama 2012: 177, unnumbered fig.

Material examined. Male (OMNH-Ar-10297), 5.8 mm, female (OMNH-Ar-10298), 6.3 mm, and ovigerous female (OMNH-Ar-10359, not dissected), 5.8 mm, mouth of Tadori River in Bishamon, Minami-shimoura-cho, Miura City , Kanagawa Prefecture, 35°08′35″N, 139°39′49″E ( Fig. 1E View Fig ), brackish, intertidal, sandy mud and gravel bottom under stones, 7 June 2015, coll GoogleMaps . M GoogleMaps . Taru; male (OMNH-Ar-10301), 7.0 mm, and ovigerous female (OMNH-Ar-10302), 6.7 mm, anchialine pool in Okada-shinkai, Izu Oshima Island ( Oshima Town ), Tokyo Prefecture, 34°47′41″N, 139°21′34″E ( Fig. 1F View Fig ), brackish, 1.5 m deep, sandy mud bottom, using SCUBA, 31 March 2017, coll GoogleMaps . O GoogleMaps . Hoshino; male (OMNH- Ar-10299), 4.9 mm, and ovigerous female (OMNH- Ar-10300), 4.2 mm, mouth of Aono River in Minato, Minami-izu Town , Shizuoka Prefecture, 34°38′05″N, 138°53′11″E ( Fig. 1G View Fig ), brackish, sandy mud bottom with Hamabo Hibiscus hamabo Sieb GoogleMaps . and Zucc. and a mangrove Kandelia obovata Sheue, Liu and Yong , 31 August 2014, coll . M GoogleMaps . Taru.

Additional material. Holotype: male (OMNH- Ar-3855), 6.9 mm, intertidal zone at mouth of Yodo River in Osaka City , Osaka Prefecture (34°41′N, 135°25′E), brackish, sandy mud bottom mixed with gravel, 11 May 1991, coll. H. Ariyama. GoogleMaps Paratype: male (OMNH-Ar-3857), 6.1 mm, same data as holotype.

Diagnosis. Antenna 2 peduncle robust in large male. Male gnathopod 1, merus bearing 2 distal projections; carpus with 3 posterodistal teeth, middle and posterior teeth large; propodus almost straight, anterodistal corner without small projection. Male gnathopod 2, carpus long, 1.4–1.5 times as long as propodus; propodus curved posteriorly in large male. Uropod 1 peduncle without inter-ramal process.

Description of male (based on OMNH-Ar-10297, 5.8 mm). Body ( Fig. 9 View Fig ) slender, pereon segments lacking ventral process. Eyes small (16% length of head). Antenna 2 ( Fig. 10A, A View Fig 1 View Fig ) stout, length about half of body; length ratio of peduncular articles 3–5 1.0: 2.7: 2.9, article 3 with 2 medial and 2 ventral robust setae, article 4 bearing 3 medial robust setae; flagellum short, consisting of 6 normal and 1 minute articles, articles 2–6 with 1, 1, 1, 1, 2 robust setae, respectively.

Gnathopod 1 ( Fig. 10B View Fig ) large; coxa trapezoidal; basis wide, lateral surface with ridge, posterior margin convex; ischium short, posterodistal corner a little projected; merus projected posterodistally, distal margin with small projection and several setae; carpus extremely wide, posterodistal margin with 3 teeth (anterior one small, middle and posteri- or ones large); propodus widened in middle; dactylus slightly curved posteriorly, posterior margin minutely serrate. Gnathopod 2 ( Fig. 10C, C View Fig 1 View Fig ) slender; coxa trapezoidal; basis slightly curved anteriorly; merus setose on posterodistal margin; carpus elongate, about 1.4 times as long as propodus, posterior margin setose; propodus with 3 and 3 robust setae on posterodistal corner and posterior margin, respectively, anterior and distal margins setose; dactylus slightly curved posteriorly, posterior margin minutely serrate.

Uropod 1 ( Fig. 10D View Fig ) relatively long; dorsal surface of peduncle bearing 3 lateral and 3 medial robust setae, ventrodistal end lacking inter-ramal process; both rami about half length of peduncle, outer ramus subequal to inner ramus, former with 3 dorsal and 4 terminal robust setae, latter bearing 1 dorsolateral, 2 dorsomedial and 5 terminal robust setae.

Description of female (based on OMNH-Ar-10298, 6.3 mm). Generally similar to male except for antenna 2, gnathopods and oostegites. Antenna 2 a little slenderer than male (OMNH-Ar-10297), flagellar articles 2–6 with 1, 1, 2, 2, 2 robust setae, respectively. Gnathopod 1 ( Fig. 11A, A View Fig 1 View Fig ) slightly stout; coxa trapezoidal; basis slightly broadened, lateral surface with ridge; merus trapezoidal, not projected posterodistally, distal margin setose; carpus triangular, anterior and posterior margins setose, middle of posterior margin with single robust seta; propodus wide, about 1.1 times as long as carpus, posterodistal corner and posterior margin with 3 and 2 robust setae, respectively, anteromedial surface and anterodistal corner setose; dactylus gradually curved, posterior margin minutely serrate. Gnathopod 2 ( Fig. 11B, B View Fig 1 View Fig ) slender; coxa trapezoidal; basis straight; merus setose on posterodistal margin; carpus not elongate, slightly widened in middle, posterior margin with many thick and normal setae; propodus about 85% as long as carpus, with 3 and 2 robust setae on posterodistal corner and posterior margin, respectively, anterior margin and anterodistal corner setose; dactylus slightly curved posteriorly, posterior margin minutely serrate.

Variation in male gnathopod 1. Large male (OMNH- Ar-10301, 7.0 mm; Fig. 11C View Fig ): posterior tooth on posterodistal margin of carpus longer, propodus almost straight, posterior margin of dactylus smooth. Middle-sized male [paratype (OMNH-Ar-3857), 6.1 mm; Fig. 11D View Fig ]: almost same as OMNH-Ar-10297, 5.8 mm.

Coloration in life ( Fig. 2D, E View Fig ). Eyes black and white; head, pereonites and pleonites brown; antennae mostly pale red; other appendages whitish, but propodi of gnathopods 1 and 2 each with pale red small dot and those of pereopods 3 and 4 each with red vermiform spot.

Remarks. The morphological characters of the specimens are quite similar to those of the type specimens from Osaka Prefecture. The shapes of the male antenna 2 and gnathopods change with growth [see Figs 10A–C View Fig , 11C, D View Fig and figs 7A, B, 10B of Ariyama (1996)].

Habitat. Sandy mud bottom or under stones of middle-lower intertidal zone at river mouths ( Ariyama 1996, present study); subtidal sandy mud bottom in brackish anchialine pool (present study). This species also occurs in the intertidal zone of a pebble beach at Ebisuzaki in Wakayama City , Wakayama Prefecture where freshwater oozes ( T. Wada, unpublished) . Grandidierella osakaensis can inhabit various sandy mud bottoms in a brackish environment.

Distribution. Japan: river mouths in Osaka Prefecture ( Ariyama 1996); Izumozaki coast in Shimane Prefecture ( Yamauchi et al. 2006); river mouths in Kanagawa and Shizuoka Prefectures and anchialine pool in Izu Oshima Island, Tokyo Prefecture (present study).