Rissoidea

Hydrobiidae

evolution

phylogeny

DNA

CO1

18S RNA

morphology

Balkans

Morphological characters in 33 Balkan rissooid genera (Adriohydrobia, Adrioinsulana, Alzoniella, Anagastina, Belgrandiella, Bithynia, Boleana, Bythinella, Bythiospeum, Daphniola, Dianella, Emmericia, Graecorientalia, Graziana, Grossuana, Hauffenia, Heleobia, Horatia, Hydrobia, Islamia, Lithoglyphus, Litthabitella, Marstoniopsis, Orientalina, Paladilhiopsis, Parabythinella, Pontobelgrandiella, Pseudamnicola, Pseudobithynia, Pyrgula, Sadleriana, Trichonia, Ventrosia) are discussed and illustrated based on the literature and, where necessary, on the presented additional data. These include shell macrocharacters, protoconch sculpture, soft part morphology and pigmentation, radulae, stomach, female reproductive organs, male reproductive organs. Based on partial sequences of the ribosomal 18S RNA gene, a molecular phylogeny is presented for all the genera, and based on fragments of CO1 gene in mitochondrial DNA, for all except six genera. Based on the Adams consensus tree the two gene phylogenies are summarised and systematics of the group is proposed. Adrioinsulana is considered a junior synonym of Pseudamnicola; Parabythinella a junior synonym of Marstoniopsis; a new name: Radomaniola n. gen. is proposed as a replacement name for the preoccupied Orientalina. Litthabitella, morphologically and molecularly distinct from the hydrobioids, probably belongs to the Assimineidae. Marstoniopsis belongs to the Amnicolidae, Bythinella to Bythinellidae, Lithoglyphus to Lithoglyphidae, Heleobia to Cochliopidae, Bithynia and Parabithynia to Bithyniidae, Emmericia to Emmericiidae. Paladilhiopsis and Bythiospeum belong to the Moitessieriidae, there being no reason for homologising the two genera. All the other genera belong to the monophyletic family Hydrobiidae, within which two subfamilies can be distinguished: Hydrobiinae and Sadlerianinae. The latter includes mostly very closely related genera, which makes splitting of this subfamily into more groups of this rank unjustified. The phylogeny of the molecular characters is mapped on two molecular trees. The caecal appendix on the stomach, reduction of the basal cusps on the rhachis and the so called “spermathecal duct” evolved parallelly, and are thus homoplastic. The network of pores on the protoconch and the flagellum seem to be uniquely derived. The seminal receptacles and lobes on the penis seem to be phylogenetically old, not prone to changes and rather useful in phylogeny reconstruction. The morphologically inferred relationships of Emmericiidae and the systematic position of the two species of Parabythinella are discussed in Appendix 2 and Appendix 3, respectively. Destroyed type localities of Balkan rissooids are listed in Appendix 4.