Mimoscina Pirlot 1933

Genus Mimoscina Pirlot, 1933

Mimoscina Pirlot, 1933:10.— Pirlot 1939: 29. Bowman & Gruner 1973: 12. Vinogradov et al. 1982: 122 (key), 129.

Type species: Mimoscina gracilipes Pirlot, 1933 by monotypy.

Diagnosis. As with the characters of the family with the following additions. Cuticle relatively thin, translucent, with distinct hexagonal markings. Callynophore of A1 triangular in cross-section, with slightly serrated margins. Coxae relatively small. Maxillae 1 with relatively broad palp, relatively shorter than in Mimonectes. Uropoda; rami with slightly serrated margins; outer margin of peduncle, and sometimes base of outer ramus, of U1, with fringe of minute or longer setae.

Sexual dimorphism. Females, even when immature, have a slightly inflated pereon which seems to become more inflated with maturity, although the extent of the inflation is not known because fully mature females have not been recorded, except for the questionable record of Sphaeromimonectes scinoides (Woltereck 1906).

Males have a relatively slender body, the first antennae are relatively longer, and the second antennae of mature males are longer than the first. Males also seem to have relatively longer and larger pereopods and uropoda than females of similar size (compare figs. 33 & 34). In addition, the propodus of gnathopod 1 is armed with more numerous long setae, the merus and carpus of pereopod 7 is not swollen, and the telson is relatively shorter than in females.

Remarks. This genus was established by Pirlot (1933), while erecting the family Proscinidae, to accommodate his new species, M. gracilipes, distinguished from Proscina (sensu lato) by the retractile dactyls of pereopods 5–7. Parascina setosa Barnard, 1930, transferred to the genus Mimonectes by Stephensen & Pirlot (1931) was later recognised as a species of Mimoscina by Vinogradov (1962), following the discovery of more material.

Prior to this study, the above two species were known only from three specimens each (excluding the record of Mori et al. 2010). The Dana collections provide another 19 specimens (15 females, 4 males) of Mimoscina, and two additional specimens from the north-eastern Pacific were kindly sent to me by Moira Galbraith, Institute of Ocean Sciences, Sidney, B.C., Canada.

A detailed examination of this material revealed that only one specimen, from the South China Sea (fig. 30), could be assigned to M. gracilipes, while the remainder represent a similar, but distinctive, new species. Mimoscina setosa, a species which seems to be restricted to Antarctic waters (Zeidler & De Broyer 2009) was not represented amongst the new material examined and, apart from the type, I have not seen any other specimens. Thus, three species of Mimoscina are recognised in this review.