CONICET | Buscador de Institutos y Recursos Humanos

Calliotropis is a genus distributed from Triassic to Recent, with a strong morphological conservatism, being the modern forms strikingly similar to the Mesozoic species. Some authors suggest a distinction between living and fossil representatives, including extinct species into the temporal subgenus Riselloidea Cossmann. Trochonodus Nützel et al. was also proposed for grouping the Triassic species originally assigned to Riselloidea. Major differences between Calliotropis and Riselloidea consist of the absence of umbilicus and the presence of a smaller and depressed protoconch in the latter. A phylogenetic analysis of Calliotropis was performed, including 85 shell-characters (10 continuous and 75 discrete ones) and 36 terminals. Four species of other Eucyclidae genera were included as outgroups. The ingroup comprises 12 fossil (Late Triassic?Pleistocene) and 20 living (Holocene) Calliotropis species. Searches were conducted under implied weighting (k=5?100). Our results show that the monophyly of Calliotropis is not recovered considering that Ambercyclus Ferrari et al. and Calliotropis species are internested within the same clade. Fossil species (formerly included into Riselloidea) determine a paraphyletic assemblage. Triassic species are clustered in a monophyletic Trochonodus, and Paleogene C. microglyptophorus Darragh and C. antarchais Stilwell are part of the same clade. Extant species are grouped together in most of the topologies with the presence of a wide open umbilicus and bulbous protoconch as synapomorphies. The results here presented show a complex history of the internal relationships of Calliotropis, although an exhaustive revision of characters is necessary and subject of further research.