Proscina birsteini Vinogradov, 1956

Zeidler, Wolfgang, 2012, A review of the hyperiidean amphipod families Mimonectidae and Proscinidae (Crustacea: Amphipoda: Hyperiidea: Scinoidea) 3533, Zootaxa 3533, pp. 1-74 : 14-15

Proscina birsteini Vinogradov, 1956

( Fig. 5)

Proscina birsteini Vinogradov, 1956: 202–203 , fig. 4.— Vinogradov et al. 1982: 123 (key), 126–127, fig. 54. Shih & Hendrycks 1996: 591, 596 (key), 599 (table), 600.

non — Mori et al. 2010: 3 (list), 8 (list) (see remarks).

Type material. This species was described from an immature (?) male, measuring about 6 mm, from the West Bering Sea (60°47’N 175°38’E); Vityaz stn. 591, 1500– 500 m, 13 September 1950. The unique holotype is in the ZMMU (Mb-1062) .

Diagnosis. According to Vinogradov (1956) and Vinogradov et al. (1982). Known only from the unique holotype male, 6.0 mm. Pereon not inflated. Antennae 1 relative length not recorded. Antennae 2 with distal articles missing, but still longer than half of A1. Gnathopod 1; basis relatively short, length slightly less than 0.7x remaining articles combined, about twice carpus; propodus length almost 1.5x carpus; dactyl relatively strong, length about 0.4x propodus. Gnathopod 2 marginally longer and more slender than G1; relative lengths of articles similar to G1. Pereopods not particularly slender. Pereopods 3 & 4 similar in length and structure; basis length twice merus; carpus length 1.6x merus; propodus length 0.8x carpus; dactyl a small nail, length 0.2x propodus. Pereopod 5 marginally shorter than P3; basis length 1.6x merus; carpus sub-equal in length to merus; propodus length 0.7x carpus; dactyl a very short, curved nail. Pereopod 6 similar in length, and relative lengths of articles, to P5. Pereopod 7 slightly shorter than P6; basis length almost 2.6x merus; merus relatively short, only twice length ischium; carpus length 1.4x merus; propodus as long as merus; dactyl as for P6. Uropoda not particularly slender or lanceolate; with inner ramus distinctly longer than outer for U1 & 2, and only marginally longer than peduncle. Uropod 1; inner ramus length 1.6x outer, and 1.3x peduncle. Uropod 2; inner ramus length twice outer, marginally longer than peduncle. Uropod 3; inner ramus marginally longer than outer, and 1.2x peduncle; peduncle width almost 0.6x length. Telson slightly broader than long, length about 0.6x peduncle of U3.

Colour not known for living specimen.

Remarks. This species is known only from the unique type. Unfortunately, I have been unable to examine the type, and therefore rely on the figures and description of Vinogradov (1956) to make the following comparisons.

In having simple gnathopods, this species must be compared with Mimonectes loveni , M. spandlii and M. colemani sp. nov. It might also be compared with P. stephenseni (here transferred to Mimonectes ), but in that species gnathopod 1 has small distal projections on the propodus on either side of the dactyl, the pereopods are more slender, and the uropoda are more lanceolate. It is readily distinguished from M. spandlii by the relatively longer merus of the pereopods, and from M. loveni by the more slender gnathopods, and the similar size and structure of pereopods 5–7, with the articles of pereopod 5 not being relatively broader, pereopod 6 is not relatively more slender, and the dactyl is strong, and the merus of pereopod 7 is not relatively as short. The uropoda are also less lanceolate. In the structure of the gnathopods and pereopods it closely resembles M. colemani sp. nov., and I might have considered them synonymous, except that in males of the latter the second antennae are very short, pereopod 3 is much longer than pereopods 4–6, and the uropoda are more lanceolate. It might also differ from M. colemani sp. nov. in the habitus and cuticle of males, but this is not described by Vinogradov (1956), although Vinogradov et al. (1982) say, in their diagnosis of the genus Proscina , “the integument is thin”. Thus, this species should be considered valid, pending an examination of the type and the availability of more material of this, and related species. It is here transferred to the genus Mimonectes .

Mori et al. (2010) list specimens from Sagami Bay, Japan. I have examined some of these specimens and two belong to the gammaridean family Stegocephalidae , and two are Lanceola clausi . Thus, this record should be ignored.

Distribution. Known only from the type locality, from the unique type, as detailed above.