ADVANCES IN THE SYSTEMATICS OF ERHAIA (GASTROPODA, POMATIOPSIDAE) FROM THE PEOPLES-REPUBLIC-OF-CHINA

Erhaia is a genus of rissoacean freshwater snails in the family Pomati opsidae that is, as far as now known, endemic to southern China. Some species of these small to minute snails are implicated in the transmis sion of the human lung fluke Paragonimus, and the subfamily Pomatiopsi dae includes snails transmitting human schistosomes. Species of Euhaia converge on European species of Bythinella in shell, radula, and some aspects of the female reproductive system, yet the European genus bel ongs to the family Amnicolidae (or Hydrobiidae:Amnicolinae to some aut hors). In this paper the comparative anatomy of the type species of so -called Pseudobythinella (now assigned to Euhaia) from Fujian Province is compared with two species from Hubei Province. Data are analyzed p henetically and cladistically involving comparisons with four species of Erbaia (two from Hunan Province; two from Yunnan Province) and so c alled Akiyoshia (a species of the same clade from Hunan Province) for which anatomical data have been published. Oncomelania hupensis (from China) of the Pomatiopsidae:Pomatiopsidae was the outgroup taxon. The most informative data were derived from the female reproductive system (27%), male reproductive system (18%), and radula (30%). Phylogenetic ally, due to considerable homoplasy, no phylogeny could be derived tha t shows a clear pattern of evolved relationships (42 equally parsimoni ous trees). In both analyses, Oncomelania is clearly divergent from th e other taxa. Using principal component analysis, multidimensional sca ling, and ordination of taxa in three dimensional space clearly showed considerable divergence of Akiyoshia, Erhaia jianouensis, and E. chin ensis from the other tightly clustered Pomatiopsinae:Erhaiini. Biogeog raphically, species of the Erhaiini are scattered from Yunnan Province down the Yangtze River drainage in mountainous areas, living in tiny streamlets of pure cold water. Species diversity thus far seems to be concentrated in Hunan, Hubei, and Sichuan Provinces.