Minamitalitrus, White, Kristine N., Lowry, James K. & Morino, Hiroshi, 2013

White, Kristine N., Lowry, James K. & Morino, Hiroshi, 2013, A new cave-dwelling talitrid genus and species from Japan (Crustacea: Amphipoda: Talitridae), Zootaxa 3682 (2), pp. 240-248 : 241

Minamitalitrus gen. nov.

Type species. Minamitalitrus zoltani sp. nov.

Included species. Cave-hopper. Minamitalitrus includes 1 species: M. zoltani sp. nov.

Etymology. Named for the type locality ‘Minami–Daitō jima’ in combination with the Talitrus stem.

Diagnostic description (based on male). Eyes absent. Antenna 1 long, reaching end of article 4 of antenna 2 peduncle. Antenna 2 peduncular articles slender; peduncular article 3 without ventral process. Labrum without robust setae. Mandible left lacinia mobilis 4-dentate. Maxilliped palp article 2 distomedial lobe well developed; article 4 reduced, button-shaped. Gnathopod 1 subchelate; posterior margin of carpus and propodus each with lobe with patches of palmate setae (reduced). Gnathopod 2 mitten-shaped; merus and carpus free; dactylus not modified distally. Pereopods 3–7 cuspidactylate. Pereopods 5–7 without setae along posterior margin of the dactylus. Pereopods 6–7 not sexually dimorphic, without row of short setae along posterior margin of dactyli. Pleonites 1–3 without dorsal spines. Pleopods 1–3 biramous, rami reduced. Epimera without vertical slits. Uropod 1 outer ramus slender; without marginal robust setae. Uropod 3 well developed; ramus shorter in length than peduncle. Telson incised, with 2–3 robust setae per lobe.

Remarks. Minamitalitrus belongs to the Talitrus group of 15 genera ( Lowry & Coleman 2012) all of which have mitten-shaped second gnathopods in the adult male. Based on the apparent apomorphies such as cuspidactylate pereopods 3–7, uropod 1 outer ramus without marginal robust setae, palmate lobes on the carpus and propodus of male gnathopod 1 and reduced robust setae (2–3 per lobe) on the telson, Minamitalitrus appears most similar to the only other cave-dwelling taxon in this group, the Hawaiian genus Spelaeorchestia Bousfield & Howarth, 1976 .

Spelaeorchestia , from Hawaiian lava tubes, looks similar to Minamitalitrus . The main generic level differences between these taxa are the pleopods which remain biramous in Minamitalitrus but are uniramous (vestigial, pleopods 1, 2) or absent (pleopod 3) in Spelaeorchestia .

Minamitalitrus is also similar to the terrestrial Philippine genus Curiotalitrus Lowry & Coleman, 2012 . Both have a 4-dentate left lacinia mobilis, subchelate gnathopod 1 with palmate lobes on the carpus and propodus, cuspidactylate pereopods and very similar pleopods and telson. However, Curiotalitrus has well-developed eyes, a short first antenna and a sexually dimorphic uropod 1 with marginal robust seta on the outer ramus.

Minamitalitrus may be an independently derived taxon from an unknown terrestrial taxon, either extant or extinct on Minami–Daitō jima Island.