Anthomedusae are Hydrozoan Cnidarians with a two part life-cycle, comprising a single or colonial Hydroid polyp and a Medusoid Jellyfish stage. Despite their similarities, they are not closely related to the 'True' Scyphozoan Jellyfish (which also typically have a Hydroid and a Medusoid stage). Like True Jellyfish, the polyp stage in Hydrozoans is asexual and reproduces by budding, while the Medusoid stage is sexual; however unlike True Jellyfish the sexual Medusa stage is generally small and short-lived, while the Hydroid polyps often form large, Coral-like, colonies.
In a paper published in the journal Acta Oceanologica Sinica on 6 May 2020, Caixue Zhang of the College of Chemistry and Environmental Sciences at Guangdong Ocean University, Jiaqi Huang of the College of Ocean and Earth Sciences at Xiamen University, and Shengli Sun, Sheng Ke, Guohuan Yang, Zhiguang Song, and Yaoqian Liu, also of the College of Chemistry and Environmental Sciences at Guangdong Ocean University, describe three new species of Anthomedusae from thr coasts of Guangdong Province, China.
Samples of Anthomedusae were collected from Leizhou Bay in the city of Zhanjiang and Shuidong Harbour in the city of of Maoming in Guangdong Province in May and August 2013. The vertical trawl method was used for sampling zooplankton specimens by dropping a 505-μm mesh-size plankton nets (net gape diameter, 50 cm) to the bottom of the water column and vertically lifted to the surface of water. The samples were stored in a solution of 5% formalin and classified and enumerated in the laboratory. All type specimens were stored at College of Ocean and Earth Sciences in Xiamen University.
Map of the coast of southwest Guangdong, showing the locations of Leizhou Bay (red star) and Shuidong Harbour (blue circle). Google Maps.
The first new species described is placed in the genus Zhangiella, and given the specific name condensum, meaning 'thick umbrella'. The Medusa of this species is pear-shaped, 2.5–3.5 mm high and 2.2–3.0 mm wide, with a thick mesoglea (the non-living gelatinous layer of a Medusa that gives it its structure) layer and a flat manubrium (structure on the base of a Medusa on which the mouth is mounted) without a gastric peduncle, the mouth is cruciform (cross-shaped); the gonads are perradial (located radially), and shuttle shaped; there are four radial canals, one ring canal; four kidney-shaped tentacular bulbs with 5–6 hollow tentacles, one red-brown ocellus (eye) at the base of each tentacle; the velum is narrow.
Line drawings of Zhangiella condensum. (a) Lateral view and (b) oral view. Zhang et al. (2020).
Photographs of Zhangiella condensum. (a) Lateral view; (b) oral view; and (c) gonads, apical view. Zhang et al. (2020).
The second new species is placed in the genus Hydractinia, and given the specific name leizhouensis, meaning 'from Leizhou'. The Medusa of this species is 0.5 mm high and 0.7 mm wide, with an umbrella that is nearly hemispherical, flattened at the apex without an apical projection; the manubrium is long, with one-third of its length extending beyond umbrellar margin, with a conical gastric peduncle. The strip-shaped gonads are interradial on manubrium, without medusa buds. There are four well-developed oral arms, with terminal cnidocyst clusters, and eight marginal tentacles of different sizes, the perradial tentacles are longer than the interradial ones, the marginal tentacular bulbs lackt ocelli, and each tentacle is covered by numerous cnidocyst rings. There are four radial canals, and one ring canal. The velum is narrow.
Line drawing of Hydractinia leizhouensis. Zhang et al. (2020).
Photograph of Hydractinia leizhouensis. Zhang et al. (2020).
The final new species is placed in the genus Cladosarsia, and given the specific name simplex, meaning 'simple', in reference to the tentacle structure. The Medusa of this species has a bell-shaped umbrella 2.5–3 mm in height and 1.6–2 mm in width. The exumbrella (outer surface of the umbrella) is smooth, the apical mesoglea is thick, while the lateral walls are thin, without scattered nematocysts. The manubrium is long and mallet-shaped reaching slightly beyond the velum; with a simple ring-shaped mouth. The gonads completely surround the manubrium. There are four perradial marginal tentacles, with adaxial nematocyst pads at the tentacular bulbs with abaxial red ocelli; the short tentacles bend inward, for about about a quarter of the umbrella height, with one short pedunculated cnidocyst knob and with a terminal cnidocyst knob. There are four radial canals, and one ring canal; the ends of each radial canal are connected to the endoderm of thetentacular bulbs. The velum is of medium width.
Line drawings of Cladosarsia simplex. (a) Lateral view and (b) enlarged tentacle. Zhang et al. (2020).
Photographs of Cladosarsia simplex. (a) Lateral view and (b) enlarged marginal umbrella. Zhang et al. (2020).
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