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

Protorchestiinae subfam. nov.

Included genera. Protorchestia Bousfield, 1982 ; Eorchestia Bousfield, 1984 ; Richardsonorchestia gen. nov.; Lowryorchestia gen, nov.; Serejorchestia gen. nov.

Diagnostic description. Antenna 1 short, not reaching midpoint of peduncular article 5 of antenna 2 or long, reaching midpoint or beyond midpoint of peduncular article 5 of antenna 2. Male and female gnathopod 1 posterior margin of merus, carpus and propodus each with palmate lobes. Male gnathopod 2 subovoid, propodus palm evenly convex to substraight without excavations or protuberances. Female gnathopod 2 mitten-shaped. Pereopods 3–7 simplidactylate. Pereopod 6 subequal in length or shorter than pereopod 7. Coxal gills large and plate-like without distinct lobes, unconvoluted. Uropod 1 exopodite without marginal robust setae. Telson with apical robust setae only. Female oostegite setae with curl or coil tips.

Discussion. Protorchestia species have previously been diagnosed with a 5-dentate left lacinia mobilis on the mandible (4-dentate in most other genera). However, the ancestral sister group to the talitroids, the Hyalidae , have a 5–8 dentate left lacinia mobilis ( Bousfield & Hendrycks, 2002). The 5-dentate state is therefore plesiomorphic in talitroids and should not be used in a phylogenetic classification. We consider that the short antenna 1 and weakly incrassate peduncle of antenna 2 of the South American Protorchestia nitida ( Dana, 1852) ( Fig. 4 View FIGURE 4 ) distinguishes it from all other species previously attributed to Protorchestia . Eorchestia Bousfield , from South Africa, is the only genus in which the female gnathopod 1 apparently lacks a palmate lobe on the merus but the species are not well described and it can be confirmed only for E. rectipalma ( Barnard, 1940) , being neither described nor figured in the only other known species, E. dassenensis ( Barnard, 1916) .

Three new genera are erected here: Lowryorchestia gen. nov., to accommodate two species from New Zealand one of which is described for the first time, Richardsonorchestia gen. nov. to accommodate two previously described species from Tasmania, and Serejorchestia gen. nov. to accommodate two species, one previously described from Tasmania and one from South Australia.

The ancestral protorchestiids would have had continuous, if discrete, distributions in the continent of Gondwana, before it split into West Gondwana, the forerunner of Africa and South America and East Gondwana, the forerunner of Antarctica, Australia, New Guinea, Zealandia, India, Sri Lanka and Madagascar. By the early Cretaceous 130 Ma, a seaway had developed that separated populations in South America and South Africa from those in Zealandia and Australia for the first time since the close of the Jurassic ( Myers, 2022).

Distribution. Chile: Cape Horn and Isla Navarino. South Africa: Natal. Namibia. New Zealand: North Island, South Island, Campbell Island. Australia: Tasmania and South Australia.