Apseudes Leach, 1814

Larsen, Kim, Bertocci, Iacopo & Froufe, Elsa, 2011, Apseudes talpa revisited (Crustacea; Tanaidacea). The impact on apseudidaen systematics, Zootaxa 2886, pp. 19-30 : 20

Genus Apseudes Leach, 1814

Diagnosis. Simultaneous hermaphroditism present. Body more or less dorsoventrally flattened. Carapace about as long as wide, without lateral spines anterior to the respiratory chamber but with anterolateral plumose setae. Rostrum ventrally curved and pointed. Ocular lobes conspicuous, separated from carapace by a groove, visual elements usually present. Pereonite 1 without lateral projections; pereonite 2 with or without lateral prolongation; pereonites 3–6 with lateral prolongation in anterior half (prolongations usually pointed but not necessarily acute). Pleon with five pleonites. Pleotelson as long as width of the last pereonite, with many circumplumose setae. Antennule biramous, with a row of small denticles on inner margin of the first article; inner flagellum with at least four articles (excluding the common article). Antenna peduncle article 3 much shorter than 4 and 5. Mandible with three-articulate palp, mandibular body with prominent denticulate ridge running on the outer side, from the palp insertion to beyond the molar insertion. Maxillule with bi-articulate palp. Maxilliped with one to three spiniform seta on the outer corner of the second palp article; endite without leaf-shaped seta. Cheliped and pereopod 1 with exopodite. Cheliped basis with strong ventromedial spiniform seta or spine. Pereopod 1 larger than the following pereopods, merus with dorsodistal spiniform seta. Pereopod 4 dactylus slightly reduced, with ventral spines; propodus with distal, transverse, row of short, serrated, spiniform setae. Pereopods 5–6 with row of short spiniform setae on the ventral or ventrodistal margin. Pereopod 6 with plumose setae on both margins of basis, ischium, merus, and carpus. Pleopods biramous, well developed. Uropod biramous, exopodite at least with four articles and often with pseudo-articulations.

Dimorphism. Large specimens either male (non-ovigerous) or simultaneous hermaphrodites (ovigerous). Pereonite 6 with genital cone. Cheliped carpus somewhat shorter and stouter and with two ventral spines; fixed finger with inner process. Ovigerous specimen with five pairs of oostegites, on cheliped and pereopods 1–4. Smaller specimens non-ovigerous, either females or juveniles. Pereonite 6 without genital cone. Chelipeds with female characteristics (carpus somewhat longer and thinner and without spiniform projections; slightly longer propodus, no process on fixed finger).

Remarks. The main modifications to the diagnosis of Apseudes as constructed by Guţu (2006:54) are: the presence of the denticulate ridge running on the side of the palp, down past the molar on the mandibular body; the presence of simultaneous hermaphrodites; the reduction of the pereopod 4 dactylus and the propodus with transverse row of modified setae.