Gazia, Lowry & Springthorpe, 2019

Lowry, J. K. & Springthorpe, R. T., 2019, Talitrid amphipods from India, East Africa and the Red Sea (Amphipoda, Senticaudata, Talitroidea, Talitridae), Zootaxa 4638 (3), pp. 351-378 : 358-359

Gazia gen. nov.

Type species. Gazia gazi sp. nov., original designation.

Included species. Gazia includes five species: G. ancheidos (K.H. Barnard, 1916); G. gazi sp. nov.; G. guadalupensis ( Ciavatti, 1989); G. itampolo ( Lowry & Springthorpe, 2015a) and G. samroiyodensis ( Azman, Wongkamhaeng & Dumrongrojwattana, 2014).

Ecological type. Beach-hoppers (mainly coastal supralittoral, non-substrate modifying talitrids sheltering un- der wrack) and forest-hoppers (living in forest leaf litter).

Etymology. Named for the geographic area of the type species.

Diagnostic description (based on male). Head. Eye medium (1/5–1/3 head length). Antenna 1 short, rarely longer than peduncular article 4 of antenna 2. Antenna 2 peduncular articles slender; article 3 without plate or process ventrally. Mandible left lacinia mobilis 5- or 4-cuspidate. Maxilliped palp article 2 with distomedial lobe; article 4 reduced, button-shaped, occasionally fused to article 3.

Pereon. Gnathopod 1 subchelate; posterior margin of carpus and propodus each with lobe covered in palmate setae; palm transverse. Gnathopod 2 subchelate; posterior margin of merus, carpus and propodus each without lobe covered in palmate setae; dactylus not modified distally, blunt or attenuated distally or acute distally, shorter than propodus; palm acute. Pereopods 3–7 bi-cuspidactylate. Pereopod 4 dactylus thickened proximally with notch midway along posterior margin (weak). Pereopod 5 short, less than 2/3 length of pereopod 6. Pereopod 6 not sexually dimorphic, subequal in length to pereopod 7. Pereopod 7 not sexually dimorphic (no articles expanded).

Pleon. Pleonites 1–3 without dorsal spines. Pleopods all well developed. Epimera 2–3 slits present just above ventral margins. Uropod 1 peduncle distolateral robust seta present, with simple tip; rami without apical spearshaped setae; endopod with marginal robust setae in 1 row; exopod without marginal robust setae. Uropod 2 rami without apical spear-shaped setae; endopod with marginal robust setae in 1 or 2 rows; exopod with marginal robust setae in 1 row. Uropod 3 ramus shorter than peduncle. Telson longer than broad, tapering distally, with a complete dorsal groove (or not), apically incised, with 3–9 robust setae per lobe.

Female (sexually dimorphic characters). Gnathopod 1 posterior margin of merus, carpus and propodus each without lobe covered in palmate setae. Gnathopod 2 mitten-shaped. Oostegites on gnathopod 2 to pereopod 5; setae with simple smooth tips.

Remarks. Gazia has vertical slits on the ventral margins of the epimera, but unlike Floresorchestia and Austropacifica gen. nov. it has palmate lobes only on the carpus and propodus of gnathopod 1. Gazia differs from Austropacifica in not having a modified mid-medial robust seta on the exopod of uropod 1 in adult males. Gazia has a very wide, disjunct distribution. There may be more undiscovered species, particularly on islands in the South Pacific, but the question remains—whether the palmate lobe on the merus of gnathopod 1 had been independently lost more than once.

If the epimeral slits are not considered then Gazia is morphologically similar to species of Platorchestia Bousfield, 1982 . Gazia has a slender antenna 2 (incrassate in Platorchestia ), pereopods 6–7 are not sexually dimorphic (sexually dimorphic in Platorchestia ) and vertical slits on epimera 2–3 (not present in Platorchestia ). Species of Gazia are beach-hoppers and forest-hoppers living in eastern Africa and Madagascar, Thailand and the Caribbean Sea. Species of Platorchestia are wide-spread beach-hoppers living in the Atlantic and Pacific Oceans.