Eutima taiwanensis Xu, Huang & Guo, 2019

Guo, Donghui, Xu, Zhenzu, Huang, Jiaqi, Wang, Chunguang & Lin, Mao, 2019, Two new hydrozoan species from the Taiwan Strait, China (Cnidaria: Hydrozoa: Leptothecata), Zoological Systematics 44 (3), pp. 185-190 : 188

Eutima taiwanensis Xu, Huang & Guo , sp. nov. ( Figs 6–8 )

Type materials. Holotype (TIO 033) and paratype (TIO 034–040), China, Taiwan Strait, Station ZD-MJK 571 (24 °59’N, 120°28’E), depth 80 m, sampling depth 79–0m, 29 July 2006, coll. Peng Xiang.

Diagnosis. The species is diagnosed by following: umbrella almost hemispherical, apex jelly thick; with a distinct gastric peduncle; with 12 (rarely 16) tentacles without lateral cirri, with 80–120 marginal warts with lateral cirri; with 8 gonads, 4 subumbrellar gonads sinuous-like, 4 peduncular gonads near proximal end of peduncle.

Description. Umbrella 5.0–6.0 mm in height, 8.5–12.0 mm in width, almost hemispherical, apex jelly thick, thinning towards margin; with a distinct gastric peduncle, long, tapering manubrium small, about as long as bell diameter, about 2/3 exceeding bell opening; manubrium short and thick, cross-shaped in transversal section; mouth with 4 simple, long lips with crenulated margin; with 8 gonads on radial canals, 4 subumbrellar gonads, elongated sinuous-like extending from nearly bell margin to basal part of peduncle, other 4 peduncular gonads extending from middle part of peduncle to manubrium; usually 12 long hollow marginal tentacles, rarely 16, 4 perradial, 8 adradial, with elongated conical basal marginal bulbs, laterally compressed, without lateral cirri; with 80–120 marginal warts, each with 1 pair of lateral cirri; 4 simple radial canals running from circular canal across underside of bell along peduncle to manubrium; 8 adradial statocysts; velum broad.

Distribution. Taiwan Strait, China.

Etymology. The specific name of the new species is referring to its type locality, the Taiwan Strait, China.

Remarks. The new species has following features: a distinct gastric peduncle; with 8 statocysts (rarely 12); marginal tentacles without lateral cirri; marginal warts with lateral cirri; without excretory papillae; gonads on radial canals, which in accordance with the genus Eutima of Eirenidae .

At present, 20 valid species in Eutima (including this new species) are known (Bouillon et al., 2006; Xu et al., 2014). This new species can be easily distinguished from the other species of Eutima by 8 gonads, 4 on subumbrella and 4 on peduncle; marginal tentacles without lateral cirri. It is similar to E. hartlaubi Kramp , 1958, but differs from the latter by following: 1) E. taiwanensis with 80–120 marginal warts with lateral cirri, and E. hartlaubi with 32 marginal warts with lateral cirri; 2) E. taiwanensis with 4 subumbrellar sinuous gonads, 4 peduncular gonads near proximal end of peduncle; and E. hartlaubi with 4 subumbrellar linear gonads, 4 peduncular gonads in middle part of peduncle.

Figures

Figures 6–8. Eutima taiwanensis Xu, Huang & Guo, sp. nov. 6. Oval view. 7. Lateral view. 8. Enlargement of marginal umbrella. Scale bars=5.0mm.