Mimoscina gracilipes Pirlot, 1933

Zeidler, Wolfgang, 2012, A review of the hyperiidean amphipod families Mimonectidae and Proscinidae (Crustacea: Amphipoda: Hyperiidea: Scinoidea) 3533, Zootaxa 3533, pp. 1-74 : 58-61

Mimoscina gracilipes Pirlot, 1933

( Figs. 29–31)

Mimoscina gracilipes Pirlot, 1933: 2–7 , figs. 1–3.— Pirlot 1939: 29–32, pl. 2, figs. 1–3. Vinogradov 1960: 223–224, fig. 14. Vinogradov 1964: 129–130. Vinogradov et al. 1982: 129–130, figs. 56–57. Shih & Hendrycks 1996: 591, 599 (table). Mori et al. 2010: 3 (list), 8 (list).

Type material. This species was described from an immature female, measuring about 8.0 mm (head to end of inner ramus of U3), from the north-east Atlantic, off Portugal (41°29’N 15°44’W), Princesse Alice II stn. 2882, 0–2000 m, 10 August 1909. The unique holotype is in the MOM (372131) .

Material examined. Female in poor condition ( ZMUC CRU-20428); South China Sea (06°55’N 114°02’E), Dana stn. 3688 III, 3000 mw, 8 April 1929. Mouthparts mounted on microscope slide, remainder in spirit .

Diagnosis. Known only from immature female specimens, 4.5–9.0 mm. Pereon slightly inflated. Antennae 1 slightly shorter than head and first four pereonites combined; callynophore stout, with serrated margins. Antennae 2 reduced in length, slightly more than 0.2x A1, consisting of several elongate articles, the third is the longest. Gnathopod 1; basis length 0.7x remaining articles combined, 1.4–1.5x carpus; propodus length 0.8x (or more) carpus, armed with long, fine setae on both margins and medially; dactyl relatively straight, thin, length about onequarter propodus. Gnathopod 2 similar to G 1 in length and structure; basis length 0.7x remaining articles combined, 1.6–1.8x carpus; propodus slightly longer than carpus; dactyl as for G1. Pereopods 3 & 4 similar in length and structure; basis length 1.5–1.6x merus; merus broadened distally with antero-distal corner produced over carpus; carpus slightly longer than merus; propodus sub-equal in length to carpus; dactyl very short, thin, slightly curved. Pereopods 5–7 all relatively long and slender, with thin articles, and very small, fully retractile dactyls. Pereopod 5; length 1.4x P4; basis length 1.4–1.5x merus; carpus length slightly more than 0.6x merus; propodus length 0.7–0.8x carpus. Pereopod 6 similar in length to P5; basis length 1.3–1.5x merus; carpus length 0.4x merus; propodus length 0.6–0.8x carpus. Pereopod 7 slightly shorter than P6; basis length 1.3x merus; carpus length about half merus; propodus length slightly more than 0.7x carpus. Uropoda with lanceolate rami, with serrated margins; all with rami of similar length but distinctly longer than peduncle. Uropod 1; rami length 1.7x peduncle; outer margin of peduncle with several, very short, fine setae for distal half. Uropod 2; rami length 1.5x peduncle; outer margin of peduncle armed with setae as for U1. Uropod 3; rami length twice peduncle; peduncle width about 0.3x length. Telson with rounded apex, about as wide as long, or slightly wider than long, length half (or slightly less) peduncle of U3.

Colour not known for living specimens.

Remarks. This species is readily distinguished from the following two congeners by the relatively long, slender pereopods 5–7, and by the relatively longer merus of pereopod 7.

Apart from the type, there are only three previous records of this species, Vinogradov (1960), from the tropical Pacific (immature female, 7.0 mm); Vinogradov (1964) from the Arabian Sea (immature female, 4.5 mm) and Mori et al. (2010) from off Kamogawa, Japan. The Dana only collected one damaged female specimen, about 9.0 mm, from the South China Sea.

Distribution. Recorded from the north-eastern Atlantic (type locality); the tropical Pacific, north-east of the Kermadec Islands (27°15’S 175°31’W), Vityaz stn. 3826, 0–6900 m; the northern Indian Ocean, Arabian Sea region (16°50’N 62°21’E), Vityaz stn. 4721, 1900–3750 m; off Kamogawa, Japan and the South China Sea as detailed above. The later is a new record for the genus for that region.