Sphaerocorynidae Prévot, 1959

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 66

Family Sphaerocorynidae Prévot, 1959

Sphaerocorynidae Prévot, 1959: 108 .

Diagnosis. Capitate hydroids almost always stolonal with terminal hydranths; stems monosiphonic, arising from a creeping hydrorhiza. Perisarc covering hydrorhiza, hydrocaulus, and hydrocladia (if present), terminating at hydranth base. Hydranths pyriform, with bulbous base and elongate, proboscis-like hypostome; tentacles all capitate, solid, either simple or with both simple and trifid ones present, arranged in a narrow band around broadest part of hydranth.

Gonophores eumedusoids or free medusae, arising on hydranth among or just distal to tentacles. Medusae, when present, with bell-shaped umbrella; exumbrellar nematocyst tracks present or absent; manubrium flaskshaped in juveniles, becoming quadrate to cruciform in cross-section in adults, not extending beyond velar opening; radial canals four; marginal tentacles two or four, with intermediate wart-like clusters or spiral rings of nematocysts, terminating in an oval capitulum armed with nematocysts; marginal bulbs large, adhering to exumbrella, expanded adaxially; abaxial ocelli present. Gonads confluent on perradii of manubrium.

Remarks. Prévot (1959) established Sphaerocorynidae for Sphaerocoryne Pictet, 1893 , a genus previously included in Corynidae Johnston, 1836 . The concept of the family adopted here is as proposed by Petersen (1990), who referred two genera to it ( Sphaerocoryne and Heterocoryne Wedler & Larson, 1986 ). The principal difference distinguishing them is the presence of both trifid and simple capitate tentacles in Heterocoryne , and simple capitate tentacles only in Sphaerocoryne . Where known, gonophores are free medusae in Sphaerocoryne and eumedusoids in Heterocoryne . Although Petersen (1990) suggested that the two genera “could be merged,” he treated them both as valid. Petersen’s classification of the group has been followed by authors including Cairns et al. (2002), Bouillon et al. (2006), Daly et al. (2007), and Schuchert (2009).

As discussed below, Sphaerocoryne sensu Petersen (1990) is divided into two genera here, Sphaerocoryne sensu stricto and Corynetes Haeckel, 1879 .

The cnidome in Sphaerocorynidae comprises both desmonemes and stenoteles. Five species are currently assigned to the family ( Schuchert 2009).