Genus Corymorpha M. Sars, 1835

Synonymy: See Schuchert (2010).

Diagnosis: Medusa bell apex dome-shaped or pointed. Four marginal bulbs present, without long exumbrellar spurs. With a single tentacle or three short tentacles and one long tentacle that differs not merely in size, but also in structure. Manubrium thin-walled, sausage-shaped with flared mouth rim, reaching to umbrella margin. Cnidome comprises stenoteles, desmonemes, and haplonemes.

Hydroids solitary with more or less vasiform hydranth and long caulus. Hydranth with one or several closely set oral whorls of 16 or more moniliform or filiform tentacles and one aboral whorl of 16 or more long, non-contractile filiform tentacles. Hydrocaulus stout, covered by thin perisarc, filled with parenchymatic gastrodermis, with long peripheral canals; aboral end of caulus with papillae turning more aborally into rooting filaments, rooting filaments composed of epidermis and solid gastrodermis, sometimes tips with non-ciliated statocysts. With or without asexual reproduction through constriction of tissue from aboral end of hydrocaulus. Gonophores develop on blastostyles arranged in a whorl over aboral tentacles. Gonophores remain either fixed as sporosacs or are released as free medusae.

Remarks: Corymorpha species usually have a rather simple medusa and a more complex hydroid stage offering more discriminating details. Corymorpha species that are solely based on the medusa stage are thus potentially species complexes which could be split into several species once their polyp stages become known. This is particularly pertinent for species with suspiciously wide distributions like C. forbesii.