Mimonectes Bovallius, 1885

Zeidler, Wolfgang, 2012, A review of the hyperiidean amphipod families Mimonectidae and Proscinidae (Crustacea: Amphipoda: Hyperiidea: Scinoidea) 3533, Zootaxa 3533, pp. 1-74 : 18-19

Genus Mimonectes Bovallius, 1885

Mimonectes Bovallius, 1885: 2 .— Bovallius 1889: 59. Schellenberg 1927: 599. Pirlot 1929: 46. Stephensen & Pirlot 1931: 503.

Bowman & Gruner 1973: 11. Vinogradov et al. 1982: 110 (key), 113. Vinogradov 1999: 1171. Parascina Stebbing, 1904: 20 .— Schellenberg 1927: 601–602. Pirlot 1929: 53. Sphaeromimonectes Woltereck, 1904a: 621 .— Woltereck 1904b: 629. Woltereck 1906: 865. Woltereck 1927: 80. Pirlot 1929:

54. Proscina Stephensen & Pirlot, 1931: 543–544 .— Pirlot 1932: 23; 1939: 25. Bowman & Gruner 1973: 12. Vinogradov et al.

1982: 122–123. New synonymy.

Type species: Mimonectes loveni Bovallius, 1885 . Designated by Bowman and Gruner (1973).

Diagnosis. As with the characters of the family with the following additions. Cuticle of females thin, translucent. Cuticle of males usually like that of females, but in some species it is relatively thick and opaque, sometimes with furrows. Eyes small, not discernible, or absent. Antennae 1; peduncle two-articulate. Mandibles without palp; lacinia mobilis slightly narrower than incisor; most inferior tooth of incisor strongest, separated from other teeth by large gap. Maxilliped with well-developed outer lobes. Pereopods; dactyls small, straight or curved, sometimes relatively strong, but not falcate (except P7 of females of M. alexanderi sp. nov.). Uropoda with lanceolate rami.

Eleven species.

Sexual dimorphism. Apart from the normally expected sexual differences—males lack oostegites, and when mature have well-developed genital papillae on pereonite 7, adjacent to the base of pereopod 7, and often have antennae 1 with numerous aesthetascs—the following sexual dimorphism has been noted.

The most obvious differences are found in the three new species described here, where the cuticle of males is relatively thick and opaque, and the habitus is more elongate (scinoid) than in other species, with an anteriorly broadened pereon and broad head. In the other species the cuticle of both sexes is relatively thin and translucent, and juveniles and immature specimens are very similar in habitus. However, as females reach maturity the pereon becomes relatively more inflated and in M. loveni , M. sphaericus and M. spandlii the pereon can become grossly inflated, almost spherical, when ovigerous, similar to that found in Archaeoscina .

The first antennae of males are relatively longer, and the second antennae can be almost as long as the first in mature specimens, although they are much reduced in the three new species described here, similar to females.

There is considerable variation in the relative lengths of the pereopods. In juveniles the variation between the sexes is less, but in mature specimens pereopods 5–7 are generally of similar length in males, whereas in females pereopod 5 is usually much longer than pereopod 6 or 7.

Remarks. Species of Mimonectes are similar in gross morphology, taking into account the sexual dimorphism, particularly for immature specimens. The main exception occurs in the males of the three new species described here, which differ from all other species as detailed above. Also, fully mature females of M. loveni , M. sphaericus and M. spandlii have the pereon grossly inflated when ovigerous, unlike other species. The most useful distinguishing characters are the structure of the propodus of the gnathopods, which can be simple, or have posterodistal excavations, or have distal projections over the dactyl, and the structure of the dactyl of the pereopods, which can be weak and relatively thin, or relatively strong.

The five species recognised by Vinogradov et al. (1982) are also considered valid in this review. In addition, three new species are described from the Dana collections, and three species, previously in the genus Proscina , are transferred to this genus following a review of the family Proscinidae (see previously). Thus, Mimonectes currently consists of eleven species.