Polystira and its relationship to other Neotropical Turridae

The genus Polystira Woodring, 1928 has become the name popularly associated with all extant Polystira -like turrid species in the Neotropics and subtropics. Apart from Polystira, the only other living turrids (as restricted by Bouchet et al. 2011) inhabiting the same region are species of Gemmula Weinkauff, 1875 and the deep water genus Cryptogemma Dall, 1918, both of which occur in the eastern Pacific and the western Atlantic.

Regionally, Gemmula is best known through G. hindsiana Berry, 1958 —the type species (tropical eastern Pacific)—and G. periscelida (Dall, 1889) (tropical western Atlantic). Our examination of museum and newly collected material shows that G. hindisiana consists of multiple species with distinct protoconch and teleoconch morphologies and that this composite taxon and G. persiscelida do not appear to be closely related to each other based upon both conchological character states and molecular phylogenetic analysis (see ‘Monophyly of Polystira ’ below). In a paper in which two new species of Gemmula were described from the Philippines, Olivera (2004) described and figured the morphology of a “Caribbean form” of one of his new species, Gemmula sikatunai. He detailed conchological differences between the Caribbean (Barbados) form and the Philippine type material. We consider that the specimens from off Barbados very likely belong to an unnamed species. We have also seen a few more undescribed Gemmula species from the Caribbean.

Here it should be noted that the recently described Gemmula mystica Simone, 2005 living in> 500 m water depth off São Paulo, Brazil, should be excluded from Gemmula. The shell appears to lack a well-developed principal spiral A otherwise present in the Turridae (see ‘Homology of spiral ornamentation in Turridae’ below), has an unusually robust rostrum, and the radula has hypodermic marginal teeth that are lacking in the Turridae (sensu stricto; s.s. hereafter) (Bouchet et al. 2011). This species is of uncertain systematic position but may belong to the family Borsoniidae.

Regionally, the genus Cryptogemma Dall, 1918 is known from three species in the East Pacific occurring in water depths of 1,159–2,490 m (McLean 1971) and at least one apparently undescribed species from the Caribbean off Colombia (see Invemar online database at http://siam.invemar.org.co/siam/). We have not examined specimens of these species, but at least C. eldorana (Dall, 1908) appears from its teleoconch morphology to belong to the Turridae and Cryptogemma has been placed in the Turridae based on radular characters by McLean (1971a) and Bouchet et al. (2011). Cryptogemma polystephanos (Dall, 1908), judging from the figure of the holotype given by McLean (1971b: fig. 1652), may not belong to the Turridae (s.s.).