Pseudelasmopus Ledoyer 1978

Hughes, Lauren E., 2015, Maeridae from the Indo-Pacific: Elasmopus, Leeuwinella gen. nov., Maeropsis, Pseudelasmopus and Quadrimaera (Amphipoda: Crustacea), Zootaxa 4059 (2), pp. 201-256 : 227

Pseudelasmopus Ledoyer 1978

Pseudelasmopus Ledoyer, 1978: 284 .— Lowry & Hughes, 2009: 644.

Diagnosis. Head anteroventral corner with weak notch; eyes poorlydeveloped, ommatidia scattered, ovate. Antenna 1 accessory flagellum minute, 2-article, not extending beyond flagellum article 2. Mandibular molar reduced, columnar, triturative; palp article 1 without acutely produced distal corner; article 2 longer than article 3; article 3 strongly falcate, anterodistal margin concave, with setal comb and apical setae. Maxilla 1 inner plate subtriangular with setae along entire margin. Coxa 1–4 reduced, broader than deep, less than the pereonites. Gnathopod 1 coxa anteroventral corner not produced, posteroventral corner without notch; propodus palm subacute. Gnathopod 2 (sexually dimorphic) propodus symmetrical; palm angle obtuse with pollex or subacute (greater than 90°); dactylus anterior margin with 1 seta. Pereopod 4 coxa with posterodistal lobe. Pereopods 5–7 basis and merus rectilinear, not expanded or expanded; dactylus simple. Pereonites, Pleonites and Urosomites dorsally smooth. Epimera 1–3 margins smooth. Uropod 3 rami subequal,length twice × width, longer or shorter than peduncle; apically rounded; without robust setae, with apical slender setae only. Telson deeply cleft (>66%), lobes abutting, tapering distally, with apical slender setae.

Type species. Pseudelasmopus cheliferus Ledoyer, 1978 , by original designation and monotypy.

Included species. Pseudelasmopus cheliferus Ledoyer, 1978 ; and P. walkerae sp. nov.

Remarks. The main characters used to diagnose Pseudelasmopus , uropod 3 and telson reduced, are no longer sufficient to define the genus from other Maeridae genera ( Ledoyer 1978). Therefore, the diagnosis is updated and expanded here to confirm Pseudelasmopus as a valid and distinct genus. Characters including the reduced eyes, reduced coxae, setose margin of the maxilla 1 inner plate, uropod 3 with slender setae onlyand telson without apical robust setae and only slender setae, separate this genus from the closely aligned and more speciose Elasmopus . As much as the latter characters group P. cheliferus and P. walkerae together in comparison to other Maeridae , several characters usually of generic level vary between the two known species—the gnathopod 2 chelation, expansion of the basis and merus in pereopods 5–7, uropod 3 peduncle lengthand telson size. As P. cheliferus was described from a male and P. walkerae is known only from females, there is a possibility that some of these characters relate to sexual dimorphism. Until more is known about these species, it seems more appropriate to group them together in the same genus within the Maeridae , than to establish another monotypic genus for a species only known from limited material.