Eorchestia Bousfield, 1984

Myers, Alan A., Park, Eunji & J. - P, Olivier, 2025, A revision of the family Protorchestiidae (Amphipoda: Talitroidea) with the description of two new subfamilies, three new genera and one new species, Zootaxa 5725 (3), pp. 371-390 : 375

Eorchestia Bousfield, 1984

( Fig. 2 )

Eorchestia Bousfield, 1984: 202 .— Lowry & Stoddart, 2003: 271.

Type species. Parorchestia rectipalma Barnard, 1940 .

Included species. E. rectipalma ( Barnard, 1940) ; E. dassenensis ( Barnard, 1916) .

Diagnostic description. Antenna 1 long, reaching end of antenna 2 peduncle. Mandible left lacinia mobilis 4-dentate. Male gnathopod 1 posterior margin of merus, carpus and propodus each with palmate lobes. Female gnathopod 1 posterior margin of merus, without palmate lobe, posterior margin of carpus and propodus each with palmate lobes. Uropod 1 exopodite without marginal robust setae. Oostegite setae curl tipped.

Remarks. Eorchestia rectipalma ( Barnard, 1940) , the type species of the genus, was originally very incompletely described by Barnard (1940). His illustrations show a sexually dimorphic subchelate gnathopod 1 with palmate lobes on the merus, carpus and propodus in the male, but only on the carpus and propodus in the female. In the original description of Eorchestia, Bousfield (1984) gave no indication of material examined and provided no new illustrations. Based on the key in Griffiths (1976) one can infer that pereopod 7 is not sexually dimorphic. Eorchestia Bousfield , from South Africa, is the only genus in which the female gnathopod 1 lacks a palmate lobe on the merus but the species are not well described and that character state can be confirmed only for E. rectipalma ( Barnard, 1940) , being unknown in E. dassenensis ( Barnard, 1916) , the only other known species. The female oostegite setae apparently have curl tips.

Habitat. Estuarine, beneath logs and debris washed up on the banks of an estuary.

Distribution. South Africa: Cape Peninsula ( Barnard, 1916); St. Lucia ( Griffiths, 1974b); Kosi Bay ( Griffiths, 1974b); Richards Bay ( Griffiths, 1974b); Amalangha River ( Griffiths, 1974b); Umzimbazi River ( Griffiths, 1974b), Plettenberg Bay: Keurbooms River ( Barnard, 1916, 1940); Port Edward ( Griffiths, 1974b). Namibia: Lüderitz Bay: Redford Bay ( Griffiths, 1974a).

Figures

FIGURE 2. Male gnathopod 2 of A. Microrchestiinae; B. Protorchestiinae. M. bousfieldi Lowry & Peart, 2010; C. notabilis (Barnard, 1935); R. rupestris (Richardson, 1993); E. rectipalma (Barnard, 1940); E. P. nitida (Dana, 1852). All redrawn from the authorities original illustrations, except P. nitida, from Bousfield (1982).