Richardsonorchestia palustris ( Richardson, 1993 )

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 : 382-383

Richardsonorchestia palustris ( Richardson, 1993)

( Figs 3–5 )

Eorchestia palustris Richardson, 1993: 268 , figs 1–3. Type locality. Northwest Bay, estuary of Nierinna Creek , Tasmania.

Holotype. Australian Museum P41263.

Diagnostic description. Antenna 1 long, extending just beyond distal end of antenna 2 article 5; flagellum subequal in length with peduncle. Antenna 2 short, flagellum a little longer than peduncle. Mandible left lacinia mobilis 4-dentate. Maxilliped palp stout, article 4 distinct, longer than basal width. Male and female gnathopod 1 merus, carpus and propodus each with palmate lobe. Male gnathopod 2 carpus small, cup-shaped; propodus large pyriform, palm very oblique with about 7 strong robust setae. Female gnathopod 2 mitten-shaped, merus, carpus and propodus each with palmate lobe. Pereopod 7 slightly longer than pereopod 6. Pleopods subequal, long, peduncular margins naked. Uropod 1 peduncle subequal to rami, distolateral robust seta a little over one quarter length of exopodite; rami subequal; exopodite margins naked; endopodite with 3 marginal robust setae. Uropod 2 exopodite naked, endopodite with 2 robust setae. Uropod 3 peduncle with one marginal and one subdistal robust seta; ramus three-quarters length of peduncle without marginal robust setae. Telson weakly emarginate, a little longer than broad and narrowing distally with a pairs of unequal terminal robust setae and one pair of weak marginal setae. Coxal gills plate-like, unlobed. Oostegite setae with curled tips.

Habitat. Cast weed and algal mat beside brackish creek behind dunes; at high water mark in saltmarsh; under oyster shells on mud at mid water.

Distribution. Tasmania: Nierinna Creek; Lagoons beach; Denison river; Sheepwash Bay; Western Bay; Detention River estuary.

Remarks. Richardsonorchestia palustris occurs in salt marshes ( R. rupestris occurs on rocky shores). It differs from R. rupestris in the antenna 1 flagellum being shorter than the peduncle (longer than the peduncle in R. rupestris ) and in the uropod 1 distolateral robust seta being less than one third the length of the exopodite (nearly half the length of exopodite in R. rupestris ).

Figures

FIGURE 3. Oostegites of A. Microrchestinae and B. Protorchestinae. Cochinorchestia metcalfeae redrawn from Lowry & Peart (2010); Microrchestia bousfieldi redrawn from Lowry & Springthorpe (2015); Protorchestia nitida redrawn from Bousfield (1982); Lowryorchestia campbelliana redrawn from Bousfield (1964); Richardsonorchestia palustris redrawn from Richardson (1993); Serejorchestia lakei redrawn from Richardson (1996).

FIGURE 4. Antenna 1 and antenna 2 of Protorchestiinae. P. nitida Bousfield redrawn from Bousfield (1982); R. palustris redrawn from Richardson (1993); S. lakei redrawn from Richardson (1996).

FIGURE 5. Telsons of species of A) Serejorchestia gen. nov., B) Richardsonorchestia gen. nov. and C) Lowryorchestia gen. nov. S. lakei redrawn from Richardson (1996); S. ceduna redrawn from Serejo & Lowry (2008); R. rupestris and R. palustris redrawn from Richardson (1993); L. campbelliana redrawn from Bousfield (1964).