Capeorchestia, Lowry, J. K. & Baldanzi, S., 2016

Lowry, J. K. & Baldanzi, S., 2016, New talitrids from South Africa (Amphipoda, Senticaudata, Talitroidea, Talitridae) with notes on their ecology, Zootaxa 4144 (2), pp. 151-174 : 158-163

Capeorchestia gen. nov.

Type species. Orchestia capensis ( Dana, 1853) .

Included species. Capeorchestia includes 1 species: A. capensis ( Dana, 1853)

Diagnostic description. Head. Eyes present (size not recorded). Antenna 1 short, rarely longer than peduncular article 4 of antenna 2. Antenna 2 peduncular articles slender; article 3 without plate or process ventrally. Mandible left lacinia mobilis 4-cuspidate. Maxilliped palp article 2 with distomedial lobe; article 4 fused with article 3.

Pereon. Gnathopod 1 sexually dimorphic; parachelate; posterior margin of propodus with lobe covered in palmate setae; palm acute. Gnathopod 2 subchelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; dactylus not modified distally, blunt, shorter than propodus; palm extremely acute (concave). Pereopods 3–7 bi-cuspidactylate. Pereopod 4 dactylus thickened proximally with notch midway along posterior margin. Pereopod 5 dactylus long, slender. Pereopod 6 not sexually dimorphic, subequal in length to pereopod 7. Pereopods 6–7 without row of short setae along the posterior margin of the dactyli. Pereopod 7 not sexually dimorphic (no articles expanded); propodus without large distal tuft of setae. Female oostegites setae with simple smooth tips.

Pleon. Pleonites 1–3 without dorsal spines. Pleopods all well developed. Epimera 1–3 slits absent. Uropod 1 peduncle distolateral robust seta absent; rami without apical spear-shaped setae; inner ramus with marginal robust setae in 2 rows (small, slender); outer ramus with marginal robust setae in one row (small, slender). Uropod 2 rami without apical spear-shaped setae; inner ramus with marginal robust setae in 2 rows (large, stout); outer ramus with marginal robust setae in 1 row (large, stout). Uropod 3 ramus longer than or subequal in length to peduncle. Telson broader than long, rounded distally, apically incised, with at least 10 robust setae per lobe.

Remarks. Only two genera, Bellorchestia Serejo & Lowry, 2008 , and Capeorchestia have male gnathopod 1 with a palmate lobe only on the propodus. They differ in a number of generic level characters: left lacinia mobilis 4-cuspidate in Capeorchestia (5-cuspidate in Bellorchestia ); antenna 2 slender in Capeorchestia , (incrassate in Bellorchestia ); maxillipedal palp article 4 fused to article 3 (forming a reduced button in Bellorchestia ); and pereopods 6 and 7 not sexually dimorphic in Capeorchestia (sexually dimorphic in Bellorchestia ).

In other respects Capeorchestia appears to be similar to Africorchestia Lowry & Coleman, 2011 . Capeorchestia differs from Africorchestia in having 4 cusps in the left lacinia mobilis (5 in Africorchestia ), in having palmate lobes only on the propodus of male gnathopod 1 (carpus and propodus in Africorchestia ), pereopods 6–7 not sexually dimorphic (sexually dimorphic in Africorchestia ), without setae along dactyli (present in Africorchestia ) and in having a dorsally smooth pleosome (sculptured in Africorchestia ). These genera apparently all share a post-Gondwanan origin (see Lowry & Springthorpe 20 15b).