Cordagalmatidae, P. R. Pugh, 2016

P. R. Pugh, 2016, A synopsis of the Family Cordagalmatidae fam. nov. (Cnidaria, Siphonophora, Physonectae), Zootaxa 4095 (1), pp. 1-64 : 7

Family Cordagalmatidae fam. nov.

The basic distinguishing character for all cordagalmatid species is that they possess heart-shaped nectophores, very distinct from those of any other physonect siphonophore. The taxonomic position of the family is discussed below. The species of the family Cordagalmatidae described herein can clearly be divided into two genera, one monotypic, based on the structure of the tentillum, and the presence/absence of a palpacle attached to the palpon. In the genus Cordagalma Totton the tentillum is of a so-called larval-type (see below), without a terminal filament bearing nematocysts or an involucrum, and has three types of nematocyst, including stenoteles in the non-spiralled cnidoband. The palpon is palpacleless. For Cardianecta gen. nov. the tentillum is a complex structure with an involucrum and, at some stage in its development a spiralled cnidoband. Only one type of nematocyst, probably a mastigophore, was found in the cnidoband, while the terminal process, and particularly the two horn-like appendages protruding from it contained desmonemes The palpon bore a palpacle, although it tended to become detached from the adult, preserved ones.

The differences between the two genera appear significant, particularly with regard to the tentilla and their completely discrete cnidomes. Thus, as is discussed below, it may well be that the genus Cardianecta gen. nov. does not actually belong to the family Cordagalmatidae, but this can only be resolved when genetic studies are made on further material. The genus Cardianecta gen. nov. is monotypic for Cardianecta parchelion sp. nov. The genus Cordagalma , presently, is considered to include two species, C. ordinatum (Haeckel) and C. tottoni Margulis, 1993 . However, for the latter species the only definite taxonomic character that we know is the structure of the nectophore. The tentilla, palpons and bracts described by Margulis in association with these nectophores do not conform with the same structures found in other Cordagalma species, but it is far from certain that they actually belong to the same specimen as the nectophores. Thus, although for convenience the species tottoni is included in the genus Cordagalma below, it must be kept in mind that it may not actually be a cordagalmatid. As well as considering all the aforementioned species, a further four new Cordagalma will be described herein.