Curiotalitrus, Lowry, James K. & Coleman, Charles Oliver, 2012

Lowry, James K. & Coleman, Charles Oliver, 2012, A new terrestrial talitrid genus from the Philippine Islands (Crustacea, Amphipoda, Talitrida, Talitridae) and the designation of two informal subgroups, Zootaxa 3400, pp. 64-68 : 66

Curiotalitrus gen. nov.

( Fig. 1 )

Type species. Curiotalitrus curioi Javier & Coleman, 2010 .

Included species. Land-hoppers. Curiotalitrus includes 1 species: C. curioi Javier & Coleman, 2010 .

Etymology. Named for the type species ‘ C. curioi ’ in combination with the Talitrus stem.

Diagnostic description (based on male). Eyes medium (greater than 1/5 to 1/3 head length). Antenna 1 slightly longer than peduncular article 4 of antenna 2. Antenna 2 peduncle slender; peduncular article 3 without ventral process. Mandible left lacinia mobilis 4-dentate. Maxilliped palp article 2 with well-developed lobe; article 4 small, well defined. Gnathopod 1 subchelate; posterior margin of carpus and propodus with palmate lobe s. Gnathopod 2 mitten-shaped; dactylus not attenuated; posterior margin of merus, carpus and propodus with palmate lobes. Pereopods cuspidactylate. Pereopod 4 significantly shorter than pereopod 3; dactylus slender without notch midway along posterior margin. Pereopods 5–7 without setae along posterior margin of the dactylus. Pereopods 6–7 not sexually dimorphic. Pleopods 1–3 well developed. Epimera without stridulating organs. Uropod 1 peduncle with distolateral robust seta; rami without apical spear-shaped setae; inner ramus distally expanded, somewhat spoon-shaped, with marginal robust setae. Uropod 3 ramus shorter than peduncle. Telson apically incised with 3–6 robust setae per lobe.

Remarks. Without a morphological and/or molecular phylogenetic analysis it is not possible to relate Curiotalitrus to other members of the Talitrus group with any reliability. Based on the 4-dentate left lacinia mobilis, the subchelate male gnathopod 1 with palmate lobes on the carpus and propodus and the presence of marginal robust setae on the outer ramus of uropod 1, Curiotalitrus is morphogically similar to the New Zealand terrestrial genus Kanikania . Curiotalitrus differs from Kanikania in the non-sexually dimorphic first gnathopods (sexually dimorphic in Kanikania ); in the fused 1-articulate pleopodal rami (multi-articulate in Kanikania ); in the sexually dimorphic uropod 1 (not modified in Kanikania ); and in the telson with 3 robust setae per lobe (only 1 seta per lobe in Kanikania ).

If the same characters are considered for all talitrid genera plus the setal pattern on the telson, then Curiotalitrus appears to be similar to two Australian coastal talitrid genera, Australorchestia Serejo & Lowry, 2008 from Western Australia and Notorchestia Serejo & Lowry, 2008 , a widespread genus from southern Australia. Curiotalitrus differs from both of these genera in the neotenic development of male gnathopod 2; in the fused 1-articulate pleopodal rami (multi-articulate in Australorchestia and Notorchestia ); and in the sexually dimorphic uropod 1 (not modified in Australorchestia and Notorchestia ). It differs further from Australorchestia in the maxillipedal palp in which the article 2 medial lobe is well developed (absent in Australorchestia ) and article 4 is small but well defined (reduced and button-shaped in Australorchestia ). It differs further from Notorchestia in the peduncular articles of antenna 2 which have sparse, small robust setae (large and numerous in Notorchestia ).

Curiotalitrus has secondary sexual dimorphism in uropod 1. In females both rami are apically slender, but in males the inner ramus is dorsoventrally widened and the inner ramus is distally expanded, somewhat spoon-shaped and rounded. The function of this adaptation is not know, but may be associated with reproduction, possibly sperm transfer.

Distribution. Panay Island, Philippine Islands.

Figures

FIGURE 1. Curiotalitrus curio (Javier & Coleman, 2010). Male: a. telson; b. uropod 3; c. habitus; d. gnathopod 2; e. maxilliped palp; f. gnathopod 1; g. mandible, left incisor, lacinia mobilis; h. pereopod 4, distal articles; i. uropod 1; j. gnathopod 1, distal articles; k. pereopod 4, dactylus; l. pleopod 1; m. pleopod 3; o. pleopod 2. Female: n. uropod 1 (after Javier & Coleman, 2010, except g).