Williams, S.T. (2012). Advances in molecular systematics of the vetigastropod superfamily Trochoidea. —Zoologica Scripta, 41, 571–595.

The gastropod superfamily Trochoidea Rafinesque, 1815 is comprised of a diverse range of species, including large and charismatic species of commercial value as well as many small or enigmatic taxa that are only recently being represented in molecular studies. This study includes the first sequences for rarely collected species from the genera Gaza Watson, 1879, Callogaza Dall, 1881, Antimargarita Powell, 1951 and Kaiparathina Laws, 1941. There is also greater taxon sampling of genera that have proved difficult to place in previous phylogenetic analyses, like Tectus Montfort, 1810, Tegula Lesson, 1832, Margarites Gray, 1847, Margarella Thiele, 1893 and trochoid skeneimorphs. There is also greater sampling of poorly represented families Solariellidae and Liotiidae. Bayesian analysis of combined gene data sets based on four (28S, 12S, 16S and COI) or five genes (plus 18S) suggests that there are eight, possibly nine families in Trochoidea including the families Margaritidae and Tegulidae, which are recognized for the first time at familial rank. Other trochoidean families confirmed are Calliostomatidae, Liotiidae, Skeneidae, Solariellidae, Trochidae and Turbinidae. A clade including Cittarium and the commercially important genera Rochia and Tectus may represent a possible ninth family, but this is not formally recognized or described here and awaits confirmation from further studies. Relationships among families were not generally well supported except in the 5-gene tree. In the 5-gene tree, Turbinidae, Liotiidae, Tegulidae, Cittarium, Rochia and Tectus form a well-supported clade consistent with the previous molecular and morphological studies linking these groups. This clade forms another well-supported clade with Margaritidae and Solariellidae. Trochidae is sister to Calliostomatidae with strong support. Subfamilial relationships within Trochidae are consistent with recent molecular studies, with the addition of one new subfamily, Kaiparathininae Marshall 1993 (previously a tribe). Only two subfamilies are recognized within Turbinidae, both with calcareous opercula: Prisogasterinae and Turbininae. Calliostomatidae includes a new subfamily Margarellinae. Its assignment to Calliostomatidae, although well supported by molecular evidence, is surprising considering morphological evidence.