The collapse of Mitra: molecular systematics and morphology of the Mitridae (Gastropoda: Neogastropoda)

Alongside confirmation of the monophyly of the gastropod family Mitridae, a recent molecular phylogenetic analysis disclosed multiple inconsistencies with the existing taxonomic framework. In the present study, we expanded the molecular sampling to 103 species, representing 26% of the 402 extant species currently accepted in the family and 16 of the 19 currently accepted extant genera; 83 species were sequenced for four molecular markers [cytochrome c oxidase subunit I (COI), 16S and 12S rRNA, and H3 (Histone 3)]. Molecular analyses were supplemented by morphological studies, focused on characters of the radula and, in a more restricted data set, proboscis anatomy. These data form the basis for a revised classification of the Mitridae. A first dichotomy divides mitrids into two unequal clades, Charitodoron and the Mitridae s.s. Species of Charitodoron show profound differences to all other Mitridae in foregut anatomy (lacking an epiproboscis) and shell morphology (smooth columella, bulbous protoconch of non-planktotrophic type), which leads to the erection of the separate family Charitodoronidaefam. nov. Three traditional subfamilies (Mitrinae, Cylindromitrinae and Imbricariinae) correspond to three of the inferred phylogenetic lineages of Mitridae s.s.; we redefine their contents, reinstate Strigatellinae Troschel, 1869 as valid and establish the new subfamily Isarinae. In the absence of molecular material, a sixth subfamily, Pleioptygmatinae, is included in Mitridae based on morphological considerations only. To resolve the polyphyly of Mitra and Cancilla in their current taxonomic extension, we reinstate the genera Episcomitra Monterosato, 1917, Isara H. & A. Adams, 1853 and Probata Sarasúa, 1989 and establish 11 new genera: Quasimitra, Roseomitra, Fusidomiporta, Profundimitra, Cancillopsis, Pseudonebularia, Gemmulimitra and Neotiara in Mitrinae; Imbricariopsis in Imbricariinae; Carinomitra and Condylomitra are left unassigned to a subfamily. Altogether 32 genera are recognized within the family. Their diversity and distribution are discussed, along with general trends in morphological evolution of the family.