Review of the fossil record of the Australian land snail genus Bothriembryon Pilsbry, 1894 (Mollusca: Gastropoda: Bothriembryontidae): new distributional and geological data

Abstract

The land snail genus Bothriembryon Pilsbry, 1894, endemic to southern Australia, contains seven fossil and 39 extant species, and forms part of the Gondwanan family Bothriembryontidae. Little published data on the geographical distribution of fossil Bothriembryon exists. In this study, fossil and modern data of Bothriembryon from nine Australian museums and institutes were mapped for the first time. The fossil Bothriembryon collection in the Western Australian Museum was curated to current taxonomy. Using this data set, the geological age of fossil and extant species was documented. Twenty two extant Bothriembryon species were identified in the fossil collection, with 15 of these species having a published fossil record for the first time. Several fossil and extant species had range extensions. The geological age span of Bothriembryon was determined as a minimum of Late Oligocene to recent, with extant endemic Western Australian Bothriembryon species determined as younger, traced to Pleistocene age. Extant Bothriembryon species from the Nullarbor region were older, dated Late Pliocene to Early Pleistocene. Cave environments proved an excellent source of fossil Bothriembryon material, where shells often showed signs of predation. The dataset from this study provided insights into the origin and radiation of Bothriembryon, and will enable future phylogenetic dating.