Anomalodesmata bivalves are extremely rare, occupying restricted ecological niches and generally found in deep waters. In addition to scarce anatomical knowledge and molecular sequences, little is known about the internal relationships. This paper includes morphological data from the Clistoconchidae (non-carnivorous lineage) and the carnivorous families Bentholyonsiidae, Spheniopsidae, Cetoconchidae and Protocuspidariidae in a cladistic context for the first time. Our study represents the largest morphological dataset compiled to date for anomalodesmatan bivalves, including taxa from all 22 extant families and provides a new topology that is in general agreement with the best estimates produced by molecular data alone.

Murrayidae (Murrayon, Dactylobiotus and Macroversum) contains hydrophilic and freshwater species, and represents an asexual lineage. Owing to the integrative description of Paramurrayon meieri sp. nov., we performed multigene phylogenetic analyses of the family, identifying a new evolutionary line. This led to the erection of Paramurrayon gen. nov. and the development of possible scenarios of the evolution of the taxa within Murrayidae based on synapomorphic characters. New photographs with descriptions of new characters of several species of Murrayon allowed for a better species definition.

The freshwater snail genus Semisulcospira is highly divergent in the ancient Lake Biwa, Japan. We used population genetics and machine learning classification of shell morphology to clarify the species diversity and delimitation of the genus. Based on the nine genetic clusters being well discriminated morphologically, our systematics successfully arranged taxonomic accounts of eleven known and two new species. Intraspecific variation in the shell and radula highlights the plastic adaptation to various diets, substrates and flow velocities.