CLADISTIC-ANALYSIS OF THE XANTHONYCHIDAE (=HELMINTHOGLYPTIDAE) (GASTROPODA, STYLOMMATOPHORA, HELICODIEA)

A cladistic analysis of the family Xanthonychidae (= Helminthoglyptida e) was carried out. The data set consisted of 34 characters and 25 ter minal taxa (including the four outgroups: Oreohelix, Neohelix, Helix, and Bradybaena). Two different analyses were performed using the progr am Hennig86. The preferred hypothesis is represented by one of the two trees obtained after successive weighting in the first analysis, whic h has the same topology of one of the original set of 50. The conclusi ons of this study suggest that: (1) the family Xanthonychidae as defin ed by Pilsbry (1939) and Zilch (1959-1960) is a paraphyletic group, (2 ) Bradybaenidae, Helicidae and Xanthonychidae form a monophyletic grou p and therefore should be analyzed together as a unit, (3) based upon the preferred hypothesis, three monophyletic groups can be defined, al though taxonomic changes will have to wait until a new analysis of the Bradybaenidae-Xanthonychidae-Helicidae group is performed.