Liuomelita, Yanrong & Zhu & Sha & Ren, 2021

Yanrong, Wang, Zhu, Chaodong, Sha, Zhongli & Ren, Xianqiu, 2021, Liuomelita mollipalma, a new genus and species of Melitidae (Amphipoda: Hadzioidea) from hydrothermal vents of the Okinawa Trough, North-West Pacific, Journal of Natural History 55 (19 - 20), pp. 1299-1310 : 1300-1301

Genu s Liuomelita gen. nov.

Type species

Liuomelita mollipalma sp. nov.

Diagnosis

Body compressed, pereion smooth, pleon dorsally dentate. Head without notch on lower margin. Lower lip with well-developed inner lobes. Maxilla 1 inner plate subtriangular, with inner margin setose. Maxilla 2 inner plate with facial row of setae present. Pereopod 1 (gnathopod 1) alike in both sexes. Pereopod 2 (gnathopod 2) of male, propodus only with long plumose setae, without strong setae (‘spines’), inner face of palm soft, without seta or protuberance; dactylus strongly curved, tapering, outer margin bearing transverse rows of short setae. Pereopod 2 of female relatively small, similar to pereopod 1. Urosome with dorsal teeth on posterior margin of urosomites 1 and 2. Uropod 1 peduncle without interramal spur. Uropod 3 outer ramus elongate, 2-ariculate; inner ramus small, oval. Telson fully cleft, consisting of two oval parts.

Relationships

Liuomelita gen. nov. belongs clearly in the Melitidae for its strongly elongated outer ramus of uropod 3 and well-developed inner lobes of the lower lip. Three groups, Melita , Eriopisa and Eriopisella , present in this family (e.g. Karaman 1984; Van Der Ham and Vonk 2003; Sawicki et al. 2005; Lowry and Springthorpe 2009; Labay 2016). The combination of the strongly inaequiramous uropod 3 with inner ramus reduced to a scale and article 2 of the outer ramus very short, the palp of mandible normal and the presence of dorsal teeth on the pleon identify the genus as a member of the Melita group. Jarret and Bousfield (1996) redefined the Melita group of Barnard and Barnard (1983), and recent works on the Melita group are by Labay (2013, 2014, 2016) based on the collections from the coastal waters of Sakhalin.

The new genus has a close relationship to Abludomelita Karaman, 1981 and Ledoyeromelita Labay, 2016 for the inner plate of maxilla 2 with facial oblique row of numerous setae; to the genera Ledoyeromelita and Paraniphargus Tattersall, 1925 for the slightly reduced palp of the mandibles; and to Melita Leach, 1814 and Paraniphargus for the dactylus of gnathopod 2 in male pointed, lower margin of the head without notch, the uropod 1 without interramal spur, and the palm of pereopod 2 in both sexes without teeth. However, it differs from Abludomelita by the anterior lobe of head truncated, not rounded, the lower margin of the head without notch, the palp of the mandible medium reduced, the uropod 1 without interramal spur, the palm of the pereopod 2 in both sexes without teeth; differs from Ledoyeromelita by the triangular inner plate of maxilla 1 with inner margin bearing numerous robust setae; and differs from Melita and Paraniphargus by the presence of dorsal teeth on pleon segments.

Exitomelita Tandberg, Rapp, Schander, Vader, Sweetman and Berge, 2011 is the first melitid that was reported from a vent field. Liuomelita differs from it by the presence of eyes, the absence of the spur on uropod 1, and sexual differentiation.

Etymology

The genus Liuomelita is named in honour of the famous Chinese carcinologist Ruiyu Liu (J. Y. Liu), combined with the older genus name Melita . The name is feminine in gender.