Two new species of Ovassiminea Thiele, 1927 (Truncatelloidea: Assimineidae) from tropical Australia

This study reports Ovassiminea Thiele, 1927 (Truncatelloidea: Assimineidae) for the first time in Australia, and two new species, Ovassiminea annulata n. sp., and Ovassiminea miskellyi n. sp., are described. They share a combination of morphological characters similar to the genus type species Ovassiminea dohrniana (Nevill, 1880), such as radular and shell morphology, configuration of the glandular oviduct, and a distinctly undulating anterior vas deferens, the latter a possible autapomorphy for the genus. Maximum Likelihood and Bayesian Inference analyses of a COI mitochondrial fragment (625 bp) suggest evolutionary affinities of the two Australian taxa to the Australian genus Cryptassiminea Fukuda & Ponder, 2005 and Assiminea grayana Fleming, 1828. Of the two new species, O. annulata possesses stronger spiral sculpture, a more pronounced internal protuberance on the operculum, and three pairs of basal cusps on the radula as opposed to two in O. miskellyi. Both species share a long penial papilla that is absent in O. dohrniana. The two species are not sympatric, with O. annulata occurring from the western Gulf of Carpentaria to Darwin, Northern Territory, and with O. miskellyi known from northern Kimberley and the Preston Peninsula, Pilbara, Western Australia.