Rhizophysidae, Brandt, 1835

Pugh, P. R., 2019, A history of the sub-order Cystonectae (Hydrozoa: Siphonophorae), Zootaxa 4669 (1), pp. 1-91 : 74

Key to the species of the Family Rhizophysidae

It should be noted that all four recognised rhizophysid species possess relatively large pneumatophores, compared with Physonectae species, and, uniquely have finger-like processes from the gas gland, called hypocystic villi, hanging down from the base of the pneumatophore.

1. Young gastrozooids with lateral wing-like structures, ptera ...................................Genus Bathyphysa ... 2. Young gastrozooids without lateral wing-like structures...................................... Genus Rhizophysa ...3.

2. Tentacles without side branches, tentilla.................................................... Bathyphysa conifera Tentacles with side branches, tentilla....................................................... Bathyphysa sibogae

3. Tentacles with simple tubular tentilla................................................... Rhizophysa eysenhardtii Tentacles with three types of complex tentilla............................................... Rhizophysa filiformis