Family Csiromedusidae, fam. nov.

Diagnosis. Narcomedusae with perradial undivided stomach pouches, extending to point of origin of tentacles; tentacles perradial, alternating on two exumbrellar whorls, equal in number with manubrial pouches; secondary tentacles lacking; with apical, external beveled pouch [?gonads] separate from the stomach. With otoporpae. Peripheral canal system lacking.

Type genus. Csiromedusa gen. nov.

Remarks. A comparison of the diagnostic characters of the families of Narcomedusae is presented in Table 1. The Csiromedusidae appears to be most closely related to the Cuninidae, in that the stomach pouches are perradial in both families, whereas they are interradial in the Aeginidae and lacking in the Solmarisidae, and in the ratio of tentacles to stomach pouches, being 1: 1 in the Cuninidae and Csiromedusidae, but 1: 2 in the Aeginidae and not comparable to the Solmarisidae .

However, in the Cuninidae, the stomach pouches are rounded to rectangular in shape, whereas in the Csiromedusidae, they are narrow and pointed in shape. The most conspicuous characters separating the two families are the tentacle position and the apical morphology. In the Cuninidae (as in the Aeginidae and Solmarisidae), the tentacles are in a single whorl, whereas in the Csiromedusidae, the tentacles are positioned in two distinct whorls relative to the sculpturing of the bell. The apical surface of the bell in the existing families is smoothly rounded without an indentation, whereas in the Csiromedusidae the apex is hollowed into a broad invagination with a beveled edge, containing numerous iceberg-like structures, which have a smooth granular appearance comparable to hydrozoan gonads. Whether these structures are, in fact, gonads, or if not, just what their function might be, remains to be demonstrated. However, a beveled apical invagination and the presence of structures inside it are unique in the medusae.

Bouillon & Boero (2000).

Diagnosis. Csiromedusidae with typically 8 parameres with alternating tentacles, each paramere comprising a perradial pointed stomach pouch, a perradial tentacle, an interradial peronium, and an interradial statocyst. Type species. Csiromedusa medeopolis n. sp.