Evolution & Systematics

Specifically referring to species under the family Kirchenpaueriidea, they were referred to as primitive plumulariids because of simple nematothecae (Stechow, 1923). Particularly a cladistic analysis of the group has not yet been undertaken and the phylogeny remains unsolved. For now we conclude that the Kirchenpaueriids are the closest relatives to their ancestors. Genus' Ventromma and Kirchenpauria are very similar and are sometimes regarded as congeneric - the only difference being that the latter does not have nematothecae under naked sarcostyles.


The reason I believe this might be a species under genera Kirchenpaueriidae instead of the others, is because it's defined by the presence of one nematotheca (Leclére et al, 2007) instead of two lateral nematothecas as present in the other groups.

A possible reason for the confusion regarding phylogeny is highlighted by Gravier (1970) - the existence of intermediate forms between true medusae and simple fixed gonophores producing the gametes. The intermediate forms have different degrees of reduction of the medusae, making it difficult to ascertain the absence or presence of medusae.