Porpitidae Goldfuss, 1818

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 69

Family Porpitidae Goldfuss, 1818

Porpitae Goldfuss, 1818:1012 [emended to Porpitidae by Guilding (1828)].

Diagnosis. Capitate hydroids regarded as polymorphic floating colonies, specialized for life at ocean surface. Each colony comprising an internal float and external mantle above a large central gastrozooid, a medial ring of gonozooids, and a peripheral ring of dactylozooids. Colonies a striking blue colour in life.

Gonophores free medusae. Medusa bell-shaped; exumbrella with perradial nematocyst rows; manubrium small; radial canals four or eight; tentacle bulbs four or eight; tentacles usually two or four, with terminal knobs; ocelli lacking.

Remarks. Porpitids are now known to be anthoathecate hydrozoans instead of siphonophores or a distinct hydrozoan group, the “chondrophores” (see Edwards 1966; Brinckmann-Voss 1970; Bouillon 1985; Calder 1988; Petersen 1990; Bouillon et al. 2006; Daly et al. 2007). Bouillon (1974) concluded that the group is related to Zancleidae Russell, 1953 based on characters of morphology, histology, and nematocyst complement. That opinion, reviewed in greater detail elsewhere ( Calder 1988), has been adopted here. In a molecular study, porpitids were included by Cartwright et al. (2008) in a group with Zancleidae , Solanderiidae Marshall, 1892 , and Cladocorynidae Allman, 1872 . The name Velellidae Eschscholtz, 1829 , sometimes applied to this taxon, is predated by the name Porpitidae Goldfuss, 1818 .

The family comprises two well-known genera, Porpita Lamarck, 1801 and Velella Lamarck, 1801 . Porpema Haeckel, 1888 , is recognized as a valid genus by some authors ( Bigelow 1911; Schuchert 2009) and as a congener of Porpita by others ( Totton 1954; Bouillon et al. 2006; Schuchert 2010). Three species were considered valid in the family by Daly et al. (2007).