Eucodonium longitentaculatum Xu, Huang & Wang, sp. nov.

(Figs 3, 9)

Material examined. Holotype (TIO 013), Beibu Bay of South China Sea, station J67 (18°21'N, 108°40'E), depth 32m, 31 July 2006, coll. Donghui Guo.

Diagnosis. Umbrella with low, rounded apical process; gastric peduncle short and broad, shorter than the length of manubrium; oral tube short; mouth with 4 inconspicuous perradial lips, each containing a group of nematocysts; two opposite perradial tentacles, very long and thin, length up to 3 times bell height, with numerous prominent brown spots at irregular intervals.

Description. Medusa with bell-shaped umbrella, 1 mm in height, 0.8 mm in width, with low and rounded apical process, lateral walls thin; manubrium on well-formed peduncle, gastric peduncle short and broad, shorter than the length of manubrium, oral tube short, inconspicuous; manubrium length 3/4 of bell cavity, cylindrical, mouth quadrangular with 4 inconspicuous perradial lips, each containing a group of nematocysts; medusa buds arise from middle region of stomach; 4 narrow radial canals and circular canal present; two opposite perradial marginal bulbs containing blackish brown pigment granules, with two very long and thin tentacles, length up to 3 times bell height, with numerous prominent brown spots at irregular intervals and with a distinct terminal knob, two other opposite marginal bulbs no present; no ocelli present; velum narrow.

Distribution. Beibu Bay of South China Sea.

Etymology. The specific name is from the Latin longitentaculatum, meaning long-tentacles, referring to the morphology of the tentacles, which are very long and thin tentacles.

Remarks. The new species can be distinguished from the other species of Eucodonium by: 1) two very long and thin tentacles, length up to 3 times bell height, with numerous brown spots at irregular intervals; 2) gastric peduncle short and broad; 3) oral tube inconspicuous; 4) 4 inconspicuous perradial lips, each containing a group of nematocysts.

Funding This study was supported by Global Climate Change and Ocean Atmosphere Interaction Research (GASI-01- 02-02-03, GASI-01-02-04, GASI-01-02-02-01), the Marine Biological Sample Museum of the Chinese Offshore Investigation and Assessment, and the National Basic Research Program of China (2011CB403604).