Protiaropsis tetranema Xu, Huang & Wang

Zhenzu Xu, Jiaqi Huang, Mao Lin, Donghui Guo & Chunguang Wang, 2016, Taxonomic notes on Hydroidomedusae (Cnidaria) from South China Sea II: Family Bythotiaridae (Anthomedusae), Zoological Systematics 41 (2), pp. 149-157 : 154-155

Protiaropsis tetranema Xu, Huang & Wang , sp. nov.

( Figs 9 , 13 )

Material examined. Holotype (TIO 016), southern of South China Sea, station NNXD 12066 S 06-09, 8 July 2012. Paratype (TIO 017), one specimen, southern of South China Sea, station NNXW 12066 S 06-09, 8 September 2012. All stations (03°40’N, 105°00’E), depth 70 m, coll. Peng Xiang.

Diagonsis. High, dome shaped exumbrella with scattered cnidocysts; 4 hollow perradial tentacles, no base swelling, with terminal knob of cnidocysts; with 4 perradial marginal bulbs with a short endodermal process, extending upwards from the basal bulbs reaching 1/4 of exumbrella height; 4 elliptic pads gonads in interradial position of manubrium.

Description. Medusa with bell-shaped umbrella, 1.0– 1.2 mm in height, 0.7–0.9 mm in width, with slightly thicker jelly at apex, thinning towards the lateral walls; with scattered cnidocysts on exumbrella; manubrium pyramidal, no gastric peduncle, with a broad quadrate base, about 1/4 height of subumbrella cavity; mouth simple, with 4 slightly flared lips; gonads as 4 separated elliptic pads in interradial position on manubrium, may contact each other in perradial position; no transverse folds; 4 perradial hollow primary marginal tentacles, without base swelling, their basal part adnate to exumbrella, sunk into between two broad marginal lobes; tentacles thin and long, each with a terminal knob of cnidocysts; no secondary tentacles; 4 radial canals and circular canal; four thick perradial endodermal processes of same size extending upwards from the basal bulbs, reaching approximately 1/4 of exumbrella height; without ocelli; velum broad.

Distribution. Southern South China Sea.

Etymology. The specific name is from the Latin tetranema , meaning tetra-tentacles, referring to four perradial marginal tentacles.

Remarks. The new species is described under the genus Protiaropsis because of following: four simple radial canals, no centripetal canals, tentacles without base swelling, no secondary tentacles, gonads interradial, no transverse folds, no ocelli.

The major differences of the new species from the other species of Protiaropsis are: 1) manubrium without gastric peduncle; 2) umbrella margin with 4 hollow perradial tentacles, no base swelling, with terminal knob of cnidocysts; 3) with 4 perradial marginal bulbs with a short endodermal process extending upwards from the basal bulbs, reaching approximately 1/4 of exumbrella height; 4) 4 gonads elliptic-shaped pads in interradial position on manubrium (see the key of Protiaropsis ).

Figures

Figures 7 – 9. Bythotiaridae spp., side view. 7. Eumedusa sp. 8. Protiaropsis pedunculata Xu, Huang & Guo, sp. nov. 9. P. tetranema Xu, Huang & Wang, sp. nov. Scale bars: 7 = 1.0 mm; 8 – 9 = 0.5 mm.

Figures 10 – 13. Bythotiaridae spp. 10. Eumedusa sp., side view. 11 – 12. Protiaropsis pedunculata Xu, Huang & Guo, sp. nov. 11. Side view. 12. Gonads, apical view. 13. P. tetranema Xu, Huang & Wang, sp. nov., side view. Scale bars: 10 = 1.0 mm; 11 – 13 = 0.5 mm.