Zancleopsis oblongus Xu, Huang & Wang, 2016

Wang, Chunguang, Xu, Zhenzu, Huang, Jiaqi, Guo, Donghui, Lin, Mao & Xia, Zhen, 2016, Taxonomic notes on Hydroidomedusae (Cnidaria) from South China Sea III: Family Rathkeidae and Zancleopsidae, Zoological Systematics 41 (4), pp. 392-403 : 400-401

Zancleopsis oblongus Xu, Huang & Wang , sp. nov. ( Figs 16–21 )

Material examined. Holotype ( TIO 022 ), South China Sea, station NNXW12095 (11°58'N, 113°02'E), depth 4294 – 230 m, 1 September 2012, coll. Peng Xiang ( TIO).

Description. Mesuda up to 3.5 mm high, with apical projection, reach one-third of the total height, umbrella almost conical-shaped, higher than width, jelly thick, forming pointed apex; manubrium flask-shaped, about half as long as the bell cavity, with large quadratic base, distal part of manubrium simple, conical, mouth opening quadrangular with faint lips, margin thick provided with cnidocysts; gonads interradial, with shallow groove which may divide them into 8 adradial masses, but separated perradially; 4 radial canals and a ring canal; 2 long, opposite capitate tentacles, each with 60–65 buttony-shaped cnidocysts knobs along the whole tentacle on the abaxial side, and 2 shorter, opposed capitate tentacles, simple, terminating in a slight swelling; 4 marginal tentacular bulbs clasping umbrella margin, of which 2 long tentacular bulbs oblong-shaped, without adaxial expansion at the base of the tentacles, and other 2 shorter tentacular bulbs very small, conical-shaped, with a large, spherical-shaped adaxial expansion at tentacular base covered with cnidocysts; with abaxial ocelli on marginal bulbs; velum narrow.

Biology. A deep-water species, occurring at depths of 4294– 230 m.

Distribution. This species is rare in the southern of South China Sea, it is only known from one specimen caught in deep waters.

Etymology. The species name is from the Latin oblongus , meaning oblong, referring to the morphology of two opposite long tentacular bulbs.

Remarks. This new species has following characters which are in common with Zancleopsis Hartlaub, 1907 : umbrella with apical projection; two long and short tentacles; marginal bulbs with two adaxial cnidocysts knobs; gonads on interradial regional of manubrium with interradial grooves; abaxial ocelli on the marginal bulbs.

The new species is similar to Z. tentaculata Kramp, 1928 , but differs from the latter by following: 1) manubrium quadratic base and mouth square; 2) two long opposite tentacles with 60–65 buttony-shaped cnidocysts knobs along the whole tentacles; 3) two long tentacular bulbs oblong-like, without adaxial cnidocysts knobs; 4) gonads interradial with shallow grooves.

Key to medusa of all known Zancleopsis species.

1. Without apical projection; two long tentacles with 8–10 capitate side branches; four large hemispherical adacial cnidocysts knobs at tentacular base.............................................................................................................................................. Z. elegans Bouillon, 1978 With apical projection .......................................................................................................................................................................... 2

2. Four long capitate tentacles, each distal end with 7–15 knob-shaped cnidocysts................................... Z. symmetrica Bouillon, 1985 Two long or four capitate tentacles ......................................................................................................................................................3

3. Four short capitate, club-shaped tentacles and four large cnidocysts knobs at tentacular base ........................ Z. gotoi ( Uchida, 1927) Two long capitate tentacles .................................................................................................................................................................. 4

4. Two long capitate tentacles with 2–4 capitate side branches and two opposed rudimentary bulbs ......... Z. dichotoma ( Mayer, 1900) * Two long and two short capitate tentacles............................................................................................................................................5

5. Each long tentacle with 6–15 capitate side branches at distal end of tentacles; four large, adaxial cnidocysts knobs at all tentacular base .......................................................................................................................................................... Z. tentaculata Kramp, 1928 Each long tentacle with 60–65 buttony-shpaed abaxial cnidocysts knobs along whole tentacles; only two large, adaxial cnidocysts knobs at short tentacular bulbs; long tentacular bulbs oblong-shaped, without adaxial cnidocysts knobs ............................................. ........................................................................................................................................ Z. oblongus Xu, Huang & Wang , sp. nov. *

* Presented in China Sea. Funding This study was supported by National Natural Science Foundation of China (41406216), Global Climate Change and Ocean Atmosphere Interaction Research (GASI-01-02-02-03, GASI-01-02-04, GASI-01-02-02-01), National Special Project on Gas Hydrate (GZH201100311), the Marine Biological Sample Museum of the Chinese Offshore Investigation and Assessment, and the National Basic Research Program of China (2011CB403604).

Figures

Figures 16–18. Zancleopsis oblongus Xu, Huang & Wang, sp. nov. 16. Lateral view. 17. Enlarged lateral view of long tentacular bulb. 18. Enlarged lateral view of short tentacular bulb. Scale bars: 16=1.0mm; 17–18=0.1mm.

Figures 19–21. Zancleopsis oblongus Xu, Huang & Wang, sp. nov. 19. Lateral view. 20. Enlarged lateral view of long tentacular bulb. 21. Enlarged lateral view of short tentacular bulb. Scale bars: 19=1.0mm; 20–21 =0.1mm.