Cladonematidae Gegenbaur, 1857

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 54-55

Family Cladonematidae Gegenbaur, 1857

Cladonemiden Gegenbaur, 1857: 220 [emended to Cladonematidae by Poche (1914: 70)].

Diagnosis. Capitate hydroids stolonal, or with upright, sparingly branched colonies, arising from creeping hydrorhiza. Perisarc covering hydrorhiza and pedicels, reaching to base of hydranths. Hydranths clavate, with an oral whorl of capitate tentacles, with or without an aboral whorl of filiform sensory tentacles; hypostome conical to dome-shaped, appearing button-like, enclosing a pre-oral chamber lined with ectodermal gland cells.

Gonophores free medusae; medusa buds without a perisarcal covering, borne on hydranth proximal to capitate tentacles, and distal to filiform tentacles when present. Medusae creeping or swimming; umbrella margin with or without a ring of nematocysts; manubrium cylindrical, with or without radial pouches; apical chamber above manubrium present or absent; radial canals varying in number, bifurcated or simple. Marginal tentacles hollow, branching, usually equal in number to radial canals, bearing knobs of nematocysts and organs of adhesion. Abaxial ocelli present. Gonads surrounding manubrium, or in brood pouches, or on subumbrella.

Remarks. Petersen (1990), Bouillon et al. (2006), Schuchert (2006, 2009), and others are followed here in regarding Cladonematidae Gegenbaur, 1857 and Eleutheriidae Stechow, 1923b as identical. I had earlier held them to be distinct based on characters of the medusa stage ( Calder 1988).

Genera traditionally recognized in Cladonematidae ( Eleutheria Quatrefages, 1842a , Cladonema Dujardin, 1843 , Dendronema Haeckel, 1879 , and Staurocladia Hartlaub, 1917 ) are distinguished on the basis of differences in the medusa stage (see Schuchert 2006; Bouillon et al. 2006). Stauridium Krohn, 1853 is a synonym of Cladonema . For detailed discussion of the family, of genera assigned to it, and of taxonomic problems remaining in the group, see Schuchert (2006). A recent molecular study by Nawrocki et al. (2010) suggests that Staurocladia is congeneric with Eleutheria . About 20–23 species are currently recognized in Cladonematidae ( Daly et al. 2007; Schuchert, 2009).

Two accounts of Eleutheria were published by Quatrefages (1842a, b), and it has been unclear in which of them the name was first made available. The paper containing a full account of the taxon ( Quatrefages 1842a) is considered here to have been published first. It appeared in the November 1842 issue of Annales des Sciences Naturelles. This conclusion coincides with information on publication of the generic name Eleutheria in Neave (1939b). While results in Quatrefages (1842b) were presented at a meeting of the Académie des Sciences on 25 July 1842, the abbreviated summary appearing in Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences is undated except for the year and its publication date is taken as the end of 1842 (ICZN Art. 21.3).

Edmondson (1930) described four new species of medusae from Hawaii in the genus Eleutheria ( E. acuminata , E. alternata , E. bilateralis , and E. oahuensis ) that have been assigned in subsequent works to Staurocladia . They were distinguished on the basis of differences in arrangement of nematocyst clusters on the tentacles, a character now reported to vary considerably ( Cooke 1977). Kramp (1961) provided accounts of the four, and Cooke (1977) illustrated and briefly described medusae that he assigned with hesitation to S. bilateralis and S. oahuensis . Hydroids of Edmondson’s four nominal species are unknown, and they are not considered further here.