Pasiphaea debitusae Hayashi, 1999

[New Japanese name: Kotsuno-shira-ebi]

Figs. 7A, 8

Pasiphaea debitusae Hayashi, 1999: 281, figs. 8–10 [type locality: Banda Sea, Indonesia, 605– 576 m].— De Grave & Fransen 2011: 258.

Material examined. T/RV “Toyoshio-maru”, 2010-03 cruise, stn 13, W of Amami-ohshima Island, 28°23.54’N, 129°11.25’E, 0–500 m, bottom depths 683–708 m, 21 May 2010, ORI net oblique tow, 2 females (cl 7.6, 10.8 mm), CBM-ZC 11278.

Additional material. R/V “Hakuho-maru”, KH02-04 cruise, stn S1-B, Sulu Sea, Philippines, 07°56.50’N, 118°10.09’E, 292–296 m, 23 November 2002, beam trawl with 3 m span opening, coll. S. Ohtsuka, 1 female (cl 8.3 mm), 1 ovigerous female (cl 11.2 mm), CBM-ZC 8739.

Coloration in fresh condition (Fig. 7A). Body generally transparent, with scattered red chromatophores on lateral surfaces; dorsal and ventral margins of pleomere 6 reddish; corneas gray. Antennular peduncle and flagella semi-transparent. Antennal peduncle also semi-transparent, with red tinge on basicerite and carpocerite.

Distribution. Previously known with certainty only from the Banda Sea, Indonesia, at depths of 304–605 m (see “Remarks”). The present specimens represent new records of this species from Japan and the Philippines; the bathymetric range is also slightly extended, ranging from 292 to 708 m.

Remarks. Hayashi (1999) reviewed the Pasiphaea sivado (Risso, 1816) species group, recognizing the following nine species: P. debitusae Hayashi, 1999, P. fragilis Hayashi, 1999, P. gracilis Hayashi, 1999, P. japonica Omori, 1976, P. laevis Hayashi, 1999, P. marisrubri Iwasaki, 1989, P. philippinensis Hayashi, 1999, P. propinqua de Man, 19016, and P. sivado . Subsequently, Hayashi (2006) described a new species, P. mclaughlinae from off Taiwan, which was referred to the P. sivado species group. This informal species group is easily recognized by the possession of a posterodorsal spine on the pleomere 6 within the genus Pasiphaea Savigny, 1816 (cf. Hayashi 1999).

Pasiphaea debitusae was originally described on the basis of material from the Banda Sea, Indonesia. There have been no subsequent records of this species. The specimens examined in this study are identified with P. debitusae on account of the following features (cf. Hayashi 1999): rostrum very small, slender, less ascending compared with other species in the P. sivado species group (Fig. 8A, B); carapace dorsally rounded, with obscure branchiostegal sinus (Fig. 8A); pleomeres all rounded dorsally, pleomere 6 with posterodorsal spine (Fig. 8C); posterior margin of telson truncate; meri of pereopods 1 and 2 with 4–7 and 6–13 spiniform setae, respectively, included generally within variation range previously reported (Fig. 8D, E); ischium of pereopod 2 with 1 spiniform seta on ventral margin (Fig. 8E); and no pleurobranch on thoracomere 8. Our specimens represent the second record of the species since the original description.

Hayashi (1999) suggested that specimens from the Andaman Sea, identified with P. sivado by Wood-Mason (1892) and Wood-Mason & Alcock (1893), might represent P. debitusae, but this needs to be verified by examination of the voucher material.