Zanclea Gegenbaur, 1857

Schuchert, Peter & Collins, Richard, 2021, Hydromedusae observed during night dives in the Gulf Stream, Revue suisse de Zoologie 128 (2), pp. 237-356 : 266-268

Genus Zanclea Gegenbaur, 1857

Synonymy: See Schuchert (2010).

Diagnosis: Newly liberated medusae with two opposite tentacles, umbrella bell-shaped, four perradial exumbrellar nematocyst patches or tracts containing stenoteles; four radial canals; with two or four marginal tentacles when fully grown, tentacles with numerous abaxial extensile cnidophores containing macrobasic euryteles; mouth simple, circular; gonads inter-radial; no ocelli.

Hydroid stage colonial, with stolonal hydrorhiza, polyps sessile or with pedicels, usually unbranched, polyps monomorphic or polymorphic, when polymorphic polyps may be differentiated into gastrozooids, gonozooids, and dactylozooids; gastrozooids elongated, cylindrical or claviform, always with capitate tentacles, tentacles usually numerous and scattered over body, in some species reduced to a few tentacles; gonozooids and dactylozooids, when present, resembling reduced gastrozooids. Gonophores liberated as free medusae or rarely medusoids. Cnidome includes stenoteles and macrobasic euryteles, the latter type may be absent in the polyp stage.

Remarks: For the identification of many Zanclea species it is usually necessary to know the hydroid stage ( Boero et al., 2000; Puce et al., 2002; Maggioni et al., 2018; Schuchert, 2010). Some Teisseriidae hydroids also produce Zanclea -like medusae, but they have ocelli.

Boero et al. (2000) critically reviewed all known Zanclea , Zanclella , and Halocoryne and described several new species. Subsequently, a bewildering number of new species were described, based either solely on the medusa or the polyp stage (e. g. Gershwin & Zeidler, 2003; Puce et al., 2002; Galea, 2008; Puce et al., 2008; Xu et al., 2008; Pantos & Bythell, 2010; Hirose & Hirose, 2012; Varela, 2012; Montano et al., 2015; Pica et al., 2017). A molecular phylogeny was provided by Maggioni et al. (2018). It is now clear that the genus Zanclea is enormously diverse and the lumping of several nominal species into Zanclea costata as in Russell (1953) or Kramp (1959a, 1968) is not tenable anymore.