Triquetramana, Hendrycks & Conlan, 2003

Hendrycks, EA & Conlan, KE, 2003, New and unusual abyssal gammaridean Amphipoda from the north-east Pacific, Journal of Natural History 37, pp. 2303-2368 : 2352-2353

Triquetramana gen. nov.

Diagnosis

Eye absent; rostrum short, rounded; antenna 1 slightly shorter than antenna 2, accessory flagellum one-articulate; mandibular palp feeble, shorter than mandible body, article 3 length 0.5×article 2; maxilla 2, inner plate wide, almost twice the width of outer plate; maxilliped palp, medial margin of dactylus spinose; coxa 1, not produced anteriorly; coxa 3 larger than 4, with a bluntly rounded, posteroventral lobe, posterior margin excavate; gnathopods 1–2, propodus triangular, equal in size, carpus elongated and non-lobate; peraeopods 5–6, basis expanded, rounded, subequal, merus expanded proximally; uropods spinose, rami broadened; telson elongate, cleft deeply.

Type species Triquetramana brevipalpa sp. nov. by monotypy.

Etymology

The genus name is from the Latin triquetrus (three cornered, triangular) plus manus (hand), referring to the peculiar shape of the propodus of gnathopods 1 and 2.

Remarks

Within the genera of Eusiridae that have eusirid-like gnathopods, Triquetramana is unique in the following combination of characters: equal sized, triangular gnathopods, with the carpus of gnathopods 1 and 2 lacking a ventral lobe; the very short, mandibular palp and the proximally expanded merus of peraeopods 5 and 6. It can be differentiated easily from other similar, eusirid genera as seen in table 3.

Additionally, it differs from Eusiropsis in the smooth, posterior margins of the basis of peraeopods 5–7 (vs serrate) and in the non-calceolate antennae (vs calceolate). Furthermore, from Pareusirogenes it differs in the inner plate of maxilla 1, which has only one small, subapical setule (vs three long, apical setae).