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 Insularorchestia gen. nov. Type species. Orchestia ashmoleorum Stock, 1996 , current designation. Included species. Insularorchestia includes 3 species: I. ashmoleorum ( Stock, 1996 ) com. nov. ; I. monodi (Mateus, Mateus & Afonso, 1986) com. nov. and I. susorum sp. nov. of Stock & Biernbaum, 1994 com. nov.. Ecological type . Beach-hoppers, field-hoppers. Habitat. Sand beaches and under stones at 762 m altitude ( Stock & Biernbaum 1994 ). Etymology. From islands. Diagnostic description ( male ). Based on Mateus, Mateus & Afonso (1986), Stock (1996) , Serejo (2004) , Morino & Ortal (1995) and Stock & Biernbaum (1994) . Head. Antenna 2 peduncular articles incrassate . Mandible left lacinia mobilis 5- or 6-cuspidate. Labium without inner lobes, with possible vestigial inner lobes. Maxilliped palp article 2 with distomedial lobe; article 4 reduced, button-shaped or 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 3 or 4 groups of robust setae, subrectangular or ‘subtriangular’ with well-developed posterodistal lobe, palm transverse; dactylus simplidactylate . Gnathopod 2 subchelate; propodus palm acute , evenly rounded or irregular with small to large shallow midpalmar sinus or without distal palmar sinus ; with or without proximal spine or thumb defining palm; dactylus not modified distally, blunt or short, recurved distally or attenuated distally. Pereopods 3–7 dactyli bicuspidactylate. Pereopod 4 significantly shorter than pereopod 3 or subequal or slightly shorter than pereopod 3; carpus similar in length to that of pereopod 3 or significantly shorter than that of pereopod 3; dactylus amplidactylate, thickened proximally with notch midway along posterior margin or short, thickened. Pereopod 6 subequal in length to pereopod 7, not incrassate; basis moderately expanded; male merus and carpus not expanded or male merus expanded, carpus not expanded. Pereopod 7 not incrassate; basis broadly expanded; posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe present or posterodistal lobe absent, shallow, broadly rounded; merus expanded distally, subtriangular, anterior margin slightly convex; carpus unexpanded or expanded, subrectangular, subequal to or shorter than propodus; propodus broad or propodus slender; length 4.7–7.3 × width; propodus without large distal tuft of setae. Oostegites (female) setae with simple smooth tips. FIGURE 9. Demaorchestia pseudojoi sp. nov. (redrawn from P. joi of Miyamoto & Morino (2004)) . 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 2 rows. Uropod 2 exopod with marginal robust setae in 1 row; endopod with marginal robust setae in 2 rows. Uropod 3 ramus subequal in length to peduncle, or shorter than peduncle. Telson apically incised, with 3–6 robust setae per lobe . Remarks. Insularorchestia is most similar to Platorchestia . It differs in having a simplidactylate gnathopod 1 (cuspidactylate in Platorchestia ). Distribution. South Atlantic Ocean . Saint Helena ( Stock 1996 ); Ascension Island ( Stock & Biernbaum 1994 ). North Atlantic Ocean . Azores (Mateus, Mateus & Afonso 1986).