Thalassocalyce Inconstans, New Genus and Species, an Enigmatic Ctenophore Representing a New Family and Order

Thalassocalyce inconstans, new genus and species, is an unusual, medusa-shaped ctenophore collected in slope water off the coast of New England. It is morphologically distinct from both cydippid and lobate ctenophores, and forms the basis of a new order of the Ctenophora, Thalassocalycida and consequently a new family. Similarities to previously described medusoid larvae of ctenophores suggest a recapitulation of the thalassocalycid morphology in the ontogeny of other species.