Taxonomic Notes on Lerniana Delicado et Hauffe, 2022, Trichonia Schütt, 1980 (Truncatelloidea: Hydrobiidae: Horatiinae) and Allied Taxa

The genera: Lerniana Delicado et Hauffe, 2022, Trichonia Schütt, 1980, and two clades (“Radomaniola” elongata Radoman, 1973, and an unnamed clade referred to as “Radomaniola” sp. 1, sp. 2) whose assignment to any genus remains unknown, form sister group with the genus Radomaniola Szarowska, 2007 (Hydrobiidae W. Stimpson, 1865, subfamily Horatiinae D. W. Taylor, 1966). The paper deals with all these clades sister to Radomaniola. Cytochrome c oxidase subunit I (COI) sequences have been used to infer phylogenetic relationships between the snails collected at 15 localities in southern Greece and one in Montenegro. Thirty-two haplotypes represent eight Molecular Taxonomical Units (mOTUs) of the species level, four of them within the genus Lerniana: L. seminula (Frauenfeld, 1863), L. tritonum (Bourguignat, 1852), and two other of these four species are both described as new. First of them has been found at seven localities in Peloponnese, Attica and southern Thessaly, the second only at one locality, sympatrically with the former species. “Radomaniola” elongata does not belong to Radomaniola, and its relationships remain unknown, similarly as in other unnamed clade, whose genus-level assignment cannot currently be resolved. The shells, protoconchs, radulae, female reproductive organs and penes are presented, also for Trichonia trichonica Radoman, 1973, for which the genus assignment remains undecided based on our molecular results. The study clearly illustrates how fragmentary is our knowledge is on the real biodiversity of the minute truncatelloid gastropods, whose morphology—simple and variable—makes species distinction hardly possible. Informed decisions on species and habitat protection should consider the above.