Eucodonium bitentaculatum
Creators: name: Mao Lin
name: Zhenzu Xu
name: Jiaqi Huang
name: Donghui Guo
name: Chunguang Wang
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Cnidaria
Hydrozoa
Anthoathecata
Eucodoniidae
Eucodonium
Eucodonium bitentaculatum

description: Eucodonium bitentaculatum Xu, Huang & Guo, sp. nov.
(Figs 1, 4–6)
Material examined. Holotype (TIO 006), coastal waters of southern Taiwan, Station 18 (21°56'N, 120°46'E), horizontal towing at depth 5 m to 10 m, 1 May 2008, coll. Meng-Hsien Chen. Paratype (TIO 007–008), same data as holotype.
Diagnosis. Umbrella bell-shaped, without apical projection; manubrium with conical peduncle; oral tube long about the same length of stomach; mouth with 4 inconspicuous perradial lips, each containing a row of nematocysts; medusa buds on interradial region of stomach; two equally developed tentacles with a terminal swelling, which terminates in a thin fibrous appendage, other two opposite perradial rudimentary bulbs no tentacles; without ocelli.
Description. Medusa with bell-shaped, up to 0.5–0.8 mm in height, slight higher or as high as broad; apical jelly slightly thickened; gastric peduncle broad conical, half as long as manubrium, oral tube long, about the same length as that of stomach; manubrium length 2/3 of bell cavity, cylindrical; mouth quadrangular with 4 inconspicuous perradial lips, each containing a row of numerous nematocysts; medusa buds arise from interradial region of stomach; 4 narrow radial canals and circular canal present; 2 equally developed tentacles with a conspicuous terminal swelling terminated in a thin fibrous appendage, with large marginal bulbs containing brown pigment granules, and other 2 opposite rudimentary marginal bulbs without tentacles; no ocelli present; nematocyst not only present in terminal swelling but also along the whole tentacle covered with ring nematocysts; velum middle broad.
Distribution. Northern South China Sea (Southern Taiwan).
Etymology. The specific name is from the Latin bitentaculatum, meaning bi-tentacles, referring to the two opposite large marginal bulbs with solid equally developed tentacles.
Remarks. This new species has following characters which are in common with Eucodonium Hartlaub, 1907: quadrangular manubrium on conical gastric peduncle; mouth with 4 inconspicuous cnidocyst armed lips; medusa buds on stomach; no ocelli present.
The new species can be distinguished from the Eucodonium browni Hartlaub, 1907 by following: 1) the former has 2 opposite large marginal bulbs with solid equally developed tentacles with a conspicuous terminal swelling, which terminates in a thin fibrous appendage, and other 2 opposite marginal bulbs very rudimentary without tentacles, while the latter has 4 small marginal bulbs with 4 equally developed tentacles with a conspicuous terminal swelling, which terminal without fibrous appendage; 2) the former has 4 inconspicuous perradial lips, each containing a row of numerous nematocysts, while the latter has 4 inconspicuous perradial lips, each containing a group of about 100 nematocysts (see the key of Eucodonium).
description: Published as part of Mao Lin, Zhenzu Xu, Jiaqi Huang, Donghui Guo & Chunguang Wang, 2016, Taxonomic notes on Hydroidomedusae (Cnidaria) from South China Sea I: Family Eucodoniidae (Anthomedusae), pp. 48-53 in Zoological Systematics 41 (1) on pages 49-50, DOI: 10.11865/zs.201602, http://zenodo.org/record/269256