Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590 Author Calder, Dale R. text Zootaxa 2010 2010-08-31 2590 1 1 91 https://biotaxa.org/Zootaxa/article/view/zootaxa.2590.1.1 journal article 10.11646/zootaxa.2590.1.1 1175­5334 Genus Velella Lamarck, 1801 Velella Lamarck, 1801: 355 . Type species. Medusa velella Linnaeus, 1758 [ Velella velella ], by absolute tautonymy. Diagnosis. Porpitid hydroids with mantle and internal float oval in shape; upper surface with erect, triangular sail oriented diagonally to long axis of float. Dactylozooids with bands and patches of nematocysts; tentacles lacking. Porpitid medusae with four radial canals; tentacle bulbs four, one opposite pair lacking tentacles and the other pair with 1–2 capitate tentacles each; algal symbionts usually present, aggregated near radial canals and ring canal. Remarks. Many nominal species of this genus have been described from tropical and temperate oceans worldwide. At present, however, all are believed referable to one species, Velella velella ( Linnaeus, 1758 ) ( Calder 1988 ; Bouillon et al. 2006 ; Schuchert 2010 ).