EN
Horatia Bourguignat, 1887 was the first genus established for hydrobiid snails with valvatoid shell, and numerous valvatoid-shelled hydrobioids were classified as Horatia. The genus was the type one for some tribe/family-rank taxa. Thus it is one of the “crucial” hydrobiid genera. Horatia seems to inhabit only Croatia and Macedonia, and its type species: H. klecakiana Bourguignat, 1887, inhabits the springs in the Cetina River Valley. In the present paper the shell, operculum, soft part pigmentation, protoconch SEM microsculpture, female reproductive organs, and penis of H. klecakiana from the spring Studenci, N of Kučiće, in the valley of the Cetina River, Croatia, are described, to confirm the identity of the studied specimens with this species. Mitochondrial cytochrome oxidase subunit I (COI) and nuclear 18S ribosomal RNA gene sequences are used to infer phylogenetic relationships of Horatia, especially with Radomaniola and the sequence of Horatia from GenBank. The results suggest close relationships of the genus with Sadleriana, not with Radomaniola.