Acta Oceanol. Sin., 2010, Vol. 29, No. 2, P. 58-61DOI: 10.1007/s13131-010-0022-2http://www.hyxb.org.cn

E-mail: hyxbe@263.net

Two new species of Ectopleura from the Taiwan Strait,

China (Cnidaria, Hydroidomedusae)

LIN Mao1∗, XU Zhenzu2, HUANG Jiaqi2, WANG Chunguang1

1 Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China

2 Department of Oceanography, Xiamen University, Xiamen 361005, China

Received 22 January 2009; accepted 11 July 2009

c©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2010

AbstractTwo new species of genus Ectopleura, i.e., Ectopleura elongata sp. nov. and E. triangularis sp. nov.are described in the present paper based on type specimens from the Taiwan Strait. The types aredeposited in the Third Institute of Oceanography, State Oceanic Administration, Xiamen, China.

Key words: Ectopleura, Tubulariidae, Taxonomy, Taiwan Strait

1 Introduction

The genus Ectopleura L. Agassiz, 1862 belongsto subclass Anthomedusae Haeckel, 1879 and Fam-ily Tubulariidae Fleming, 1828. Ectopleura medusoidsis characterized by a normal, symmetrical umbrellawith eight longitudinal exumbrellar cnidocyst tracksor rows, and by two or four equally developed tentaclesor four marginal bulbs without tentacle. Medusoidsin some species reduced to radial symmetrical eume-dusoid or crytomedusoid gonophore (Petersen, 1990).This genus includes 29 species based on free medu-soids and sessile gonophores (Xu et al., 2007; Bouil-lon et al., 2006; Xu and Huang, 2006; Bouillon andBoero, 2000; Kramp, 1968; Kramp, 1961). In China’swaters, ten species of Ectopleura medusoids have beenrecorded (Xu et al., 2007; Xu and Huang, 2006; Xuet al., 1991; Li and Chen, 1991; Zhang and Lin, 1984;Xu and Zhang, 1978; Hsu and Chang, 1964; Hsu andChin, 1962; Chow and Huang, 1958).

Two preciously unknown species of Ectopleura aredescribed from plankton samples collected by R/VYanping II in the Taiwan Strait (20◦849′–27◦056′N,114◦920′–121◦241′E) during January 2007. Throughthe analysis of 250 samples of plankton, having twonew species, i.e., Ectopleura elongata sp. nov. andEctopleura triangularis sp. nov. are described in thepresent paper. Two new species with four marginaltentacles differ from the other species of Ectopleura by

having two opposite perradial tentacles, and by fourmarginal bulbs without tentacles, but similar to sevenspecies of Ectopleura by also having four equally devel-oped marginal tentacles. The major differences amongthem are summarized in Table 1.

2 Taxonomy

Family Tubulariidae Fleming, 1828Genus Ectopleura L. Agassiz, 1862Ectopleura elongata sp. nov. (Fig. 1)Type specimen: Holotype (TS 004). One speci-

men collected from Taiwan Strait at Sta. ZD-XM655(22◦01′N, 117◦52′E), 24 January 2007, depth 211 m,collected by Wang Yanguo (State Oceanic Adminis-tration).

Etymology: The specific name refers to the elon-gated conical basal bulbs of this medusae.

Diagnosis: Umbrella without apical projection,exumbrella with eight longitudinal ridges and eightcnidocyst tracks; four radial canals very broad andthick, with jagged edges; with four perradial tentac-ullar bulbs, equal size elongated conical, all tentacleswithout abaxial cnidocysts cluster and terminal knobof cnidocysts.

Description: Umbrella 3.2 mm high, 2.5 mm wide,bell-shaped, slight inner trap in apical part, withoutapical projection, mesoglea middle thick; exumbrella

Foundation item: The Marine Biological Sample Collection of the Chinese Offshore Investigation and Assessment, the ChineseOffshore Investigation and Assessment under contract Nos 908-ZC-II-02 and 908-01-ST06 (II); the National Basic Research Programof Science and Technology of China under contract No. 2006FY220700, the Scientific Research Foundation of Third Institute ofOceanography, SOA under contract No. 2009008.

∗Corresponding author, E-mail: lm3011@126.com

LIN Mao et al. Acta Oceanol. Sin., 2010, Vol. 29, No. 2, P. 58-61 59

Fig.1. Ectopleura elongata sp. nov. a. Lateral view and b. dorsal view.

with eight conspicuous longitudinal ridges, and eightlongitudinal cnidocyst tracks, originating in pairs fromthe sides of marginal bulbs, continued to apex of um-brella along the edges of eight very prominent ridges;manubrium very large, cylindrical, slightly exceedingbeyond the bell opening; mouth simple, circular; fourradial canals very broad and thick, with jagged edges,circular canal middle broad; gonad completely sur-rounding manubrium; with four perradial marginalbulbs, equal size, elongated conical, tapering towardsterminal in the form of a developed marginal tenta-cles, all tentacles without abaxial cnidocysts clustersand terminal knob of cnidocysts; velum middle broad.

Discussion: This new species has four equally de-veloped marginal tentacles; umbrella without apicalprojection; exumbrella with eight longitudinal ridgesand eight longitudinal cnidocyst tracks. These fea-tures differ from the other species of Ectopleura, but

similar to Ectopleura guangdongensis Xu, Huang etChen, 1991, while their main distinctions are:

Ectopleura guangdongensis: Manubrium tubular,about half the length of umbrella cavity; four marginaltentacular bulbs, nearly globular-shaped, each tenta-cle with seven to nine abaxial cnidocysts clusters, noneterminal knob of cnidocyst; four radial canals narrow,without jagged edges.

Ectopleura elongata: Manubrium very large,cylindrical, exceeding beyond bell opening; fourmarginal tentacular bulbs with elongated conicalbases, all tentacles without abaxial cnidocyst clustersand terminal knob of cnidocysts; four radial canalsvery broad and thick, with jagged edges.

Ectopleura triangularis sp. nov. (Fig. 2)Type specimen: Holotype (TS 005). One speci-

men collected from Taiwan Strait at Sta. ZD-MJK584(24◦34′N, 120◦00′E), 5 February 2007, depth 66 m,

Fig.2. Ectopleura triangularis sp. nov. a. Lateral view and b. enlargement of tentacle.

60 LIN Mao et al. Acta Oceanol. Sin., 2010, Vol. 29, No. 2, P. 58-61

collected by Wang Yanguo (State Oceanic Adminis-tration).

Etymology: The specific name refers to the trian-gular marginal bulbs of the medusae.

Diagnosis: Umbrella with a low and round apicalprojection; exumbrella with eight longitudinal cnido-cyst tracks, without longitudinal ridge; with a largeapical chamber in the form a pointed cone, like anapical canal; with four radial canals very broad, eachwith connected by a trans-canal in uppermost part ofmanubrium; with four marginal bulbs, equal size, tri-angular thickness of proximal bases of tentacles, withring nematocysts; with four marginal tentacles, thinand long, each without abaxial cnidocysts clusters,with a large terminal knob of cnidocysts.

Description: Umbrella 1.1 mm high (includ-ing apical projection), 0.9 mm wide, conical bell-shaped, exumbrella with scattered nematocyst clus-ter; mesoglea moderately thick, with a low and roundapical projection; exumbrella with eight longitudinalcnidocyst tracks, issuing in pairs from the side of ten-tacular bulbs and extending nearly apex of umbrella;exumbrella without longitudinal ridge; manubriumvery large, pyramidal, with a broad, quadrate base,slightly exceeding beyond the bell opening; with alarge apical chamber in the form of a pointed cone,resembling an apical canal; mouth simple, circular;gonad encircle the manubrium, leaving only proxi-

mal and mouth parts free; with four radial canalsand a circular canal, all radial canals rather broad,with a number of deep brown granules in endoderm ofradial canals, each with connected by a trans-canalin uppermost part of manubrium; with four broadmarginal bulbs, equal size, frontal view of tentacularbulbs showing triangular, thickness of proximal basesof tentacles, with ring nematocysts, from the distalunderside of which a narrow tentacle, without nemato-cyst clusters, with a large, terminal nematocyst knob;velum middle broad.

Discussion: This new species can easily be dis-tinguished from the other species of Ectopleura by itsfour equally developed marginal tentacles, umbrellawith apical projection; exumbrella without longitu-dinal ridge; with eight longitudinal cnidocyst tracks,which without extensible at bell margin, but similarto Ectopleura indica Petersen, 1990, while their maindistinctions are:

Ectopleura indica: Without apical chamber andapical canal; four radial canals narrow; four short ten-tacles, marginal bulbs conical-shaped, proximal basesof tentacles without thickness and ring nematocysts.

Ectopleura triangularis sp. nov.: With apicalchamber and apical canal; four radial canals broad andthick; four long tentacles, marginal bulbs triangular,thickness of proximal base of tentacles with ring ne-matocysts.

Table 1. The key to the new species and similar species of the genus Ectopleura1. Umbrella with apical projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Umbrella without apical projection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42. Exumbrella with 8 longitudinal ridges; 8 longitudinal nematocyst tracks which from triangular nematocyst patches

at bell margin; 4 perradial tentacles with terminal nematocyst knob and irregularly scattered nematocyst clusters;manubrium broad and large, almost filling entire subumbrellar cavity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Ectopleura latitaeniata Xu & Zhang, 1978Exumbrella without longitudinal ridges; 8 longitudinal nematocyst tracks which without extensible at bell margin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. With apical chamber and apical canal; 4 radial canals broad and thick; 4 long tentacles without nematocyst clusters,marginal bulbs triangular, thickness of proximal bases of tentacles with ring nematocysts . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. triangularis sp. nov.Without apical chamber and apical canal; 4 radial canals narrow; 4 short tentacles with scatted nematocyst, marginalbulbs conical-shaped, proximal bases of tentacles without thickness and ring nematocysts . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E. indica Petersen, 1990

4. Exumbrella with longitudinal ridge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Exumbrella without longitudinal ridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5. Manubrium tubular, about half the length of subumbrella cavity; 4 marginal tentacular bulbs, nearly globular-shaped,each tentacle with 7–9 abaxial cnidocysts clusters, none terminal cnidocyst knob; 4 radial canals narrow, withoutjagged edges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .E. guangdongensis Xu, Huang et Chen, 1991Manubrium very large, cylindrical, exceeding beyond bell opening; 4 marginal tentacular bulbs with elongated conicalbases; all tentacles without abaxial cnidocyst clusters and terminal knob of cnidocysts; 4 radial canals very broad andthick, with jagged edges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. elongata sp. nov.

6. Mouth rim studded with nematocyst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Mouth rim without studded nematocyst. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7. Manubrium short and blunt; 4 tentacles long, each with terminal nematocyst knob and 10–25 spherical, abarialnematocyst clusters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. dumortieri (van Beneden, 1844)Manubrium large filling subumbrella cavity; 4 short tentacles with terminal nematocyst knob, without abaxialnematocyst cluster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. bethae (Warren, 1908)

8. Medusoids known only while still attached to blastostyle, with 4 short tentacles with developing terminal nematocystknob . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. americana Petersen, 1990Medusoids reduced to cryptomedusoid gonophore, older gonophores without radial canals and ring canal, with 4relatively long, capitate tentacle rudiments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. radiate (Uchida, 1937)

LIN Mao et al. Acta Oceanol. Sin., 2010, Vol. 29, No. 2, P. 58-61 61

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