Nubiella terminaliknoba Xu, Guo & Wang, 2019

Wang, Xuefeng, Lin, Kun, Xu, Zhenzu, Guo, Donghui & Huang, Jiaqi, 2019, Some new Hydroidomedusa (Cnidaria) from the northern South China Sea, Zoological Systematics 44 (3), pp. 191-205 : 193

Nubiella terminaliknoba Xu, Guo & Wang , sp. nov. ( Figs 1 , 7–8 )

Material examined. Holotype (AOB-HL331), one specimen collected from Fangcheng Harbour , northern of the South China Sea, FCFD003 (21°36 ˊ N, 108°23 ˊ E), depth 16.2 m, 7 May 2015, coll. Xuefeng Wang, Kun Lin and Shaosen Wu.

Diagnosis. The species is different from others by following: medusa with apical chamber; without gastric peduncle, with oral tube; with 4 unbranched oral tentacles inserted above mouth rim; 4 tentacular bulbs large, nearly spherical, with papillar-shaped endodermal process, extending up to radial canals, tentacles short and thin, ring cnidocysts along the whole tentacles, each terminating in a large, globular cnidocyst knob.

Description. Umbrella bell-shaped, 1.0 mm in height, 0.6 mm in width, jelly evenly thick, without apical projection; manubrium cylindrical, about half of height of bell cavity, no gastric peduncle, and with very short oral tube, with a distinct, papillary apical chamber; mouth simple, circular, with 4 unbranched capitate oral tentacles attached above mouth rim; gonads encircle manubrium; 4 narrow radial canals and circular canal present; 4 tentacular bulbs large, nearly spherical-shaped, each with one tentacle, tentacular bulbs without ocelli and with black endodermal papilla, extending up to radial canals, tentacle short and thin, ring cnidocysts along whole tentacle, each terminating in a large, globular cnidocyst knob; velum narrow.

Distribution. Fangcheng Harbour, northern of the South China Sea.

Etymology. The specific name is from the Latin terminaliknoba , meaning terminal-knob, refers to tentacles with a terminal knob of cnidocysts.

Remarks. This new species can be easily distinguished from the other species of Nubiella by medusa without apical projection; without gastric peduncle; gonads encircling manubrium; exumbrella without nematocyst pouches; manubrium without medusa buds ( Xu et al., 2009; Guo et al., 2018); but similar to N. papillaris Xu, Huang & Guo, 2009 and N. apapillaris Xu, Huang & Guo, 2018 by having apical chamber, and similar to N. tubularia Xu, Huang & Guo, 2007 and N. macrogastera Xu, Huang & Lin, 2009 by having oral tube on manubrium. The new species differs from them by: 1) manubrium with apical chamber and oral tube; 2) with 4 unbranched oral tentacles; 3) 4 tentacular bulbs with papillar-shaped endodermal process, extending up to radial canals, tentacle short and thin, each terminating in a large, globular cnidocyst knob.

Key to the new species and similar species of genus Nubiella .

1. Umbrella without apical chamber; oral tube very long, about 1/2 of length of manubrium; with 8 unbranched oral tentacles.............. ................................................................................................................................................ N. tubularia Xu, Huang & Guo, 2007 Umbrella with apical chamber .............................................................................................................................................................2

2. Manubrium without oral tube............................................................................................................................................................... 3 Manubrium with oral tube....................................................................................................................................................................4

3. With 8 unbranched oral tentacles; 4 tentacular bulbs with a dense mass of black endodermal process extending up to radial canals ... ................................................................................................................................................ N. papillaris Xu, Huang & Guo, 2009 With 16 unbranched oral tentacles; 4 tentacular bulbs without endodermal process, nearly crescent-shaped........................................ .............................................................................................................................................. N. apapillaris Xu, Huang & Guo, 2018

4. With 12 unbranched oral tentacles; manubrium long and large, elliptical-shaped, about 4/5 of height of bell cavity; tentacles long and thick, without terminal knob of cnidocysts ........................................................................ N. macrogastera Xu, Huang & Lin, 2009 With 4 unbranched oral tentacles; manubrium short, cylindrical, about 1/2 of height of bell cavity; tentacles short and thin, with a terminal knob of cnidocysts ........................................................................................ N. terminaliknoba Xu, Guo & Wang , sp. nov.

Figures

Figures 1–6. Hydroidomedusa spp. 1. Nubiella terminaliknoba Xu, Huang & Guo, sp. nov., lateral view. 2. Paranubiella shenzhenensis Xu, Guo & Wang, sp. nov., lateral view. 3. Eucodonium crassonemalis Xu, Guo & Lin, sp. nov., lateral view. 4. Proboscidactyla trifurcata Xu, Huang & Guo, sp. nov., lateral view. 5. Euphysora knides Huang, 1999, lateral view. 6. Monocanna ovale (Mayer, 1900) comb. nov., oral view. Scale bars: 1=0.2mm; 2–3, 5–6=0.5mm; 4=1.0mm.

Figures 7–11. Hydroidomedusa spp., line drawing. 7. Nubiella terminaliknoba Xu, Huang & Guo, sp. nov., lateral view. 8. Ditto, enlargement of marginal tentacle. 9. Paranubiella shenzhenensis Xu, Guo & Wang, sp. nov., lateral view. 10. Eucodonium crassonemalis Xu, Guo & Lin, sp. nov., lateral view. 11. Proboscidactyla trifurcata Xu, Huang & Guo, sp. nov., lateral view. Scale bars: 7=0.2mm; 9–10=0.5mm; 11=1.0mm.