Mauritiorchestia Green, Appadoo, Lowry & Myers, 2021

Lowry, J. K. & Myers, A. A., 2022, Platorchestiinae subfam. nov. (Amphipoda, Senticaudata, Talitridae) with the description of three new genera and four new species, Zootaxa 5100 (1), pp. 1-53 : 25

Mauritiorchestia Green, Appadoo, Lowry & Myers, 2021

Type species. Mauritiorchestia fayetta Green, Appadoo, Lowry & Myers, 2021 , original designation.

Included species. Mauritiorchestia includes 1 species: M. fayetta Green, Appadoo, Lowry & Myers, 2021 .

Ecological type. Sand-hopper.

Habitat. Coastal sandy substrate with huge amount of beach wrack algae.

Diagnostic description (male).

Head. Antenna 2 peduncular articles incrassate. Mandible left lacinia mobilis 5-cuspidate. Maxilla 1 palp absent. Labium without inner lobes. Maxilliped palp article 2 with distomedial lobe; article 4 fused with article 3.

Pereon. Gnathopod 1 sexually dimorphic; subchelate; coxa much smaller that coxa 2; posterior margin of carpus and propodus each with lobe covered in palmate setae; propodus anterior margin with 4 groups of robust setae, ‘subtriangular’ with well-developed posterodistal lobe, palm transverse; dactylus simplidactylate. Gnathopod 2 subchelate; propodus palm acute, rounded distally and sigmoidal, with small to large midpalmar sinus, without proximal sinus, without large distal sinus, without proximal spine or thumb defining palm; without large projection near dactylar hinge; dactylus strongly curved, subequal in length to palm, not modified distally, blunt. Pereopods 3–5 cuspidactylate, 6–7 simplidactylate. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than that of pereopod 3; dactylus amplidactylate, thickened proximally with notch midway along posterior margin. Pereopod 6 subequal in length to pereopod 7, not incrassate; basis moderately expanded; male merus expanded, carpus not expanded. Pereopod 7 not incrassate; basis broadly expanded, posterior margin smooth or minutely serrate margin without setae, posterodistal lobe present, rounded, produced downwards almost to merus; merus expanded distally, subtriangular, anterior margin slightly straight; carpus expanded, subrectangular, subrectangular, slightly shorter than propodus; propodus slender.

Pleon. Pleopods 1–3 all well-developed. Uropod 1 peduncle distolateral robust seta absent; exopod without marginal robust setae; endopod with marginal robust setae in 1 row. Uropod 2 exopod without marginal robust setae; endopod with marginal robust setae in 1 row. Uropod 3 ramus subequal in length to peduncle. Telson completely cleft, with 3–6 robust setae per lobe.

Remarks. Mauritiorchestia is currently the only platorchestiine known from the Indian Ocean and the only platorchestiine amphipod with pereopods 3–5 cuspidactylate and 6–7 simplidactylate and lacking a palp on maxilla 1. It belongs in the group with an incrassate second antenna. It differs from Platorchestia in having a simplidactylate first gnathopod. It has a very similar gnathopod 2 palm and dactylus to the South Korean genus Demaorchestia .

Distribution. Mauritius (Green, Appadoo, Lowry & Myers 2021).