Turritopsis

Diagnosis: Medusae with high bell, proximal portion of radial canals swollen through vacuolated gastrodermal cells, forming a peduncle-like mass on top of manubrium, in larger animals continued on manubrium as perradial ribs. Tentacles numerous and evenly distributed. Mouth four-lipped, fringed with numerous spherical nematocyst clusters, these with or without a distinct stalk. Ocelli adaxial on tentacle base. Polyp stage forming erect, branching colonies, sidebranches and hydranth pedicels adnate for some distance, perisarc tubes not nested. Hydranths spindleto club-shaped; filiform tentacles scattered over much of hydranth body. Gonophores develop on the hydrocauli in perisarc covered region and are liberated as medusae.

Remarks: The genera Turritopsis McCrady, 1857 and Oceania Péron & Lesueur, 1810 are morphologically not separable (comp. Schuchert, 2016). The purported difference of the stalked oral nematocyst buttons in Oceania is not tenable as also T. nutricula has stalked clusters (see below). However, to avoid unnecessary taxonomic changes, the two genera should not be synonymized until a comprehensive molecular phylogeny using several marker genes confirms this.