Systematics, biogeography and nomenclature
According to the principles of phylogenetic systematics, the species referred to as Simnialena uniplicata should be called Cyphoma uniplicata (Fig. 3). Meanwhile, the status of the nominal genus Simnialena Cate, 1973, with its insufficiently known type species Simnialena marferula Cate, 1973, remains unclear. According to Lorenz and Fehse (2009: 105), ‘S. marferula is a close relative of S. uniplicata’. This conclusion, on which we cannot elaborate here, is based on similarities in shell morphology.
The DNA sequences of specimens belonging to Cymbovula acicularis and specimens that agree with the description of C. bahamaensis (Figs 2c-d) are almost identical. As a consequence, these nominal taxa should most probably be considered synonyms, as has also been suggested by Lorenz and Fehse (2009) based on morphological data.
There is a moderately strong supported dichotomy between the Atlantic and the Indo-Pacific taxa, with Neosimnia arcuata from the East-Pacific having an aberrant, but poorly supported, position in the cladogram, where it clusters with the Atlantic taxa. Together, these species represent the Simniinae Schilder, 1927. Furthermore, two undisputed clades were found among the Indo-Pacific taxa, supporting the occurrence of the subfamilies Prionovolvinae Fehse, 2007, and Ovulinae Fleming, 1822, respectively.
In order to get a better understanding of the phylogeny and parasite/host associations of the Atlantic Ovulidae, additional shells and DNA material are needed. DNA obtained from other ovulids occurring in the Atlantic area (e.g. Cyphoma macumba Petuch, 1979; C. versicolor Fehse, 2003; C. mcgintyi Pilsbry, 1939 ) may elucidate the taxonomical position of the genus Cyphoma as a monophyletic group. However, several ovulid species are rare and generally only their shells are found, which hampers further investigations.