Mimonecteola mixta Vinogradov

Zeidler, Wolfgang, 2009, A review of the hyperiidean amphipod superfamily Lanceoloidea Bowman & Gruner, 1973 (Crustacea: Amphipoda: Hyperiidea), Zootaxa 2000, pp. 1-117 : 106-108

Mimonecteola mixta Vinogradov

( Fig. 42)

Mimonecteola mixta Vinogradov, 1964: 122–124 , figs 8, 9. Vinogradov et al. 1982: 103–104, fig. 39. Vinogradov & Semenova 1996: 617.

Type material. This species was described from two specimens, a male measuring 10.0 mm, from near the Philippine Trench, Vitjaz Stn. 4490, and a female measuring 8.0 mm, from the equatorial Indian Ocean [00°00.5’S 83°09.7’E]; Vitjaz Stn. 4918, taken at depths of 5300–0 m and 4000–0 m respectively. Both specimens, regarded syntypes, are in the ZMMU (Mb – 1057 & 1058), on microscope slides.

Diagnosis. According to Vinogradov (1964) and Vinogradov et al. (1982). Body length of sexually mature specimens 9.5–11.0 mm. Male A2; length 0.7x A1. Gnathopod 1; dactylus slightly curved, length slightly less than half propodus. Gnathopod 2; dactylus relatively straight, length 0.4x propodus. Pereopods 3 & 4 similar in structure, with P4 slightly longer than P3; basis length 1.8x merus; carpus slightly expanded with several moderate setae on posterior margin, similar in length to basis; propodus relatively narrow, subequal in length to carpus; dactylus relatively straight, length about 0.2x propodus. Pereopod 5 marginally shorter than P4; basis length 1.7–1.9x merus; carpus length 1.3x merus; propodus of female slightly longer than carpus, with short row of paired setae on posterodistal corner, forming palmate margin shorter than length of dactylus; propodus of male slightly shorter than carpus with posterodistal margin armed with row of setae that are longer but thinner than in females; dactylus of female slightly curved, length about 0.2x propodus; dactylus length of male about 0.3x propodus. Pereopod 6 marginally longer than P4; basis length about 1.5x merus; carpus slightly longer than merus; propodus length about 1.3x carpus, in male with short posterodistal projection overlapping base of dactylus; dactylus relatively straight, length slightly more than 0.1x propodus. Pereopod 7; length about 0.7x P6 or less; basis length 2.3x merus; carpus slightly longer than merus; propodus length 1.6x carpus, with posterodistal spoon-shaped process to accommodate dactylus as in the Lanceolidae ; dactylus short, curved, partly retractile, forming weakly developed subchela with propodus, length less than 0.2x propodus. Telson rounded; length marginally more than 0.5x peduncle of U3.

Colour of living specimens not recorded.

Remarks. I have not seen any specimens of this species but accept its validity based on the observations of Vinogradov (1964) and Vinogradov et al. (1982).

This species is known only from the syntypes and one other record ( Vinogradov & Semenova 1996). It is most readily distinguished from the previously mentioned congeners by the weak subchela of pereopod 5 in combination with the partly retractile dactylus of pereopod 7. It is most similar to M. subchelata but is distinguished from it by the relatively shorter dactylus and barely perceptible subchela of pereopod 5, the partly retractile and curved dactylus of pereopod 7 that forms a weak subchela with the propodus and the relatively shorter telson. In the subchelate character of pereopod 5, it resembles the specimens described by Vinogradov (1964) as M. diomedeae and the new species described here, but in both of these species pereopod 7 is simple.

Distribution. Only known from the types from near the Philippine Trench and the tropical mid-Indian Ocean and one additional record from the tropical eastern North Pacific ( Vinogradov & Semenova 1996). It has been found in catches from 4000 m and 5300 m to the surface.