Amphinema Haeckel, 1879

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 23-24

Genus Amphinema Haeckel, 1879

Amphinema Haeckel, 1879: 49 .

Type species. Oceania dinema Péron & Lesueur, 1810 [ Amphinema dinema ], by subsequent designation by Rees & Russell (1937).

Diagnosis. Pandeid hydroids stolonal (unless Bimeria biscayana Browne, 1907 is included; see Schuchert 2007), arising from a creeping hydrorhiza. Hydrocaulus simple, slender, of moderate length, often annulated basally, gradually expanding in diameter distally. Perisarc covering hydrorhiza and hydrocaulus, terminating below hydranth base; pseudohydrotheca absent. Hydranths clavate; tentacles filiform, amphicoronate, eight or more, in a distal whorl; hypostome dome-shaped.

Gonophores free medusae; medusa buds borne on short pedicels arising from hydrorhiza, or caulus, or both. Medusae bell-shaped, usually with large apical process, gastric peduncle absent; manubrium broad at base; oral lips four, simple, little or not crenulated; mesenteries between manubrium and radial canals present or absent; radial canals four; marginal tentacles two, opposite, perradial, large; tentaculae or marginal warts present or absent; ocelli present or absent; gonads adradial, interradial, or perradial, sometimes extending onto radial canals.

Remarks. The genus Amphinema Haeckel, 1879 was founded for two nominal species, Saphenia titania Gosse, 1853 and S. apicata McCrady, 1859 . Both are now generally included in the synonymy of Oceania dinema Péron & Lesueur, 1810 (= Amphinema dinema ) ( Mayer 1910a; Russell 1953; Kramp 1961; Schuchert 2007). However, Haeckel’s (1879) account of S. titania was evidently based in part on a species not described until later, Stomotoca rugosa Mayer, 1900a (= Amphinema rugosum ) ( Rees & Russell 1937; Russell 1953).

Some misinformation exists in the literature about the type species of Amphinema . Rees & Russell (1937: 70) stated that Haeckel (1879) had fixed Amphinema titania as “genotype,” but Haeckel in fact did not designate a type species for the genus. After providing a new definition of Amphinema, Rees & Russell (1937: 70) chose A. dinema as type species. Their designation is valid because (1) no previous type species designation exists for the genus (ICZN Art. 69.1), and (2) O. dinema was included in Amphinema by Haeckel (1879) as a synonym of A. titania (ICZN Art. 67.2). This type fixation has been accepted as valid by authors including Russell (1953), Kramp (1961), and Schuchert (2007).