Richardsonorchestia, Myers & Park & J.-P, 2025

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

Richardsonorchestia gen. nov.

( Figs 2–5 )

Type species. Eorchestia palustris Richardson, 1993: 268 , figs 1–3.

Included species. R. palustris ( Richardson, 1993) ; R. rupestris ( Richardson, 1993) .

Etymology. In recognition of the work of Dr Alastair Richardson in describing the rich fauna of landhoppers in Tasmania.

Diagnostic description. Antenna 1 long, reaching near to the end of peduncle of antenna 2. Mandible left lacinia mobilis 4 dentate. Maxilliped palp article 4 longer than broad. Gnathopod 1 with palmate lobes on merus, carpus and propodus in both sexes. Gnathopod 2 strongly sexually dimorphic, subchelate in male, mitten-shaped in female. Pereopods 3–7 simplidactylate and amplidactylate. Coxal gills unbranched, plate-like. Pleopods all well developed, peduncles naked or minutely setose; rami elongate and setose. Uropods 1–2 exopodites without marginal robust setae. Telson entire or weakly emarginate. Female oostegite setae with, curl tips.

Remarks. Richardsonorchestia gen. nov. is close to Protorchestia Bousfield , from which it differs in the longer antenna 1 which reaches more than half way along peduncular article 5 of antenna 2 and unexpanded peduncle of antenna 2. It differs from Eorchestia in having a palmate lobe on the merus of the female gnathopod 1. It differs from Lowryorchestia in the distally narrow telson ( Fig. 5 ) (distally broad in Lowryorchestia ) and in having fewer setae on the female oostegites which terminate in curl tips (coil tips in Lowryorchestia ). It differs from Serejorchestia in the undivided telsonic lobes ( Fig. 5 ) and 4-dentate left lacinia mobilis.

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).

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).