Platorchestiinae subfam. nov. (Amphipoda, Senticaudata, Talitridae) with the description of three new genera and four new species Author Lowry, J. K. Author Myers, A. A. 0000-0003-3256-2123 School of Biological, Earth and Environmental Sciences, University College Cork, Cork Enterprise Centre, Distillery Fields, North Mall, Cork, Ireland. bavayia @ gmail. com; https: // orcid. org / 0000 - 0003 - 3256 - 2123 bavayia@gmail.com text Zootaxa 2022 2022-02-17 5100 1 1 53 journal article 20608 10.11646/zootaxa.5100.1.1 cabdbbb1-1226-4c2e-b90b-fae0742b5091 1175-5326 6127681 F42DAC62-0E30-442E-A375-87FC02B2CC99 Tethorchestia Bousfield, 1984 Tethorchestia Bousfield, 1984: 204 .— LeCroy, 2011: 743 , 759.— Wildish & LeCroy, 2014: 557 , 558, key.— Lowry & Myers, 2019: 84 , 87, figs 38, 39. “ Tethorchestia ”.— LeCroy, 2011: 743 , key, 757 diagnosis. Type species. Tethorchestia antillensis Bousfield, 1984 , original designation. Included species. Tethorchestia contains 3 species: T. antillensis Bousfield, 1984 ; T. karukerae Ciavatti, 1989 ; T. palaeorchestes Bousfield & Poinar, 1995 (fossil, terrestrial, Oligocene). Ecological type . Beach-hoppers. Habitat. Living on semi-protected beaches sand beaches. Diagnostic description ( male ). Based on Ciavatti (1989) and Wildish & LeCroy (2014) . Head. Antenna 2 peduncular articles slender . Mandible lacinia mobilis 4-cuspidate . Gnathopod 1 sexually dimorphic; subchelate; 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 cuspidactylate . Gnathopod 2 subchelate; propodus palm acute; propodus palm evenly rounded; without palmar sinus; without proximal sinus; without large distal sinus; without proximal spine or thumb defining palm; without large projection near dactylar hinge; dactylus short, strongly curved, longer than palm; recurved distally, attenuated distally or slender, distally acute. Pereopods 3–7 dactyli bicuspidactylate. 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 shorter than pereopod 7, not incrassate; basis moderately expanded; male merus and carpus not expanded. Pereopod 7 not incrassate; basis moderately expanded, or broadly expanded; posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe present, shallow, broadly rounded; carpus unexpanded (subrectangular); subrectangular, or subtriangular (slightly); carpus subequal to propodus; propodus broad; length 3.3–6.5 × width; propodus with large distal tuft of setae. Oostegites (female) setae with simple smooth tips. Pleon. Pleopods 1–3 all well-developed, or all reduced (slightly). Uropod 1 peduncle distolateral robust seta present; exopod without marginal robust setae; endopod with marginal robust setae in 1 row . Uropod 2 exopod with marginal robust setae in 1 row; endopod with marginal robust setae in 2 rows. Uropod 3 ramus shorter than peduncle. Telson completely cleft or apically incised, with 3–6 robust setae per lobe or with 7–9 robust setae per lobe. Remarks. Tethorchestia is very similar to Mexorchestia . Tethorchestia has a posterodistal lobe on the basis of pereopod 7 (absent in Mexorchestia ) and the oostegites have simple tips in Tethorchestia (oostegites with spatulate tips in Mexorchestia ). Distribution. Mexico and Caribbean Sea ( Bousfield 1984 , Ciavatti 1989 ).