Preliminary analysis of the phylogeny of Amphidromus from Thailand and nearby areas

unknown. The tree snail, genus Amphidromus albers, 1850 is a group of mollusks that have undergone extensive radiation and are distributed over the entire region of Southeast Asia. Within the genus, more than 300 taxa have been proposed. At present, however, 83 taxa are recognized as distinctive species. Many species of Amphidromus exhibit a great extent of variation within and between populations in shell shape, color pattern and coiling direction. Because of their intraspecific variation, the taxonomy of amphidromus has remained difficult and complicated. To reconstruct their phylogeny, cladistic analyses of shell, genital morphology and mitochondrial 16S ribosomal RNA sequences is necessary. Amphidromids tree snails were collected from various parts of Thailand including Laos, Singapore, Sumatra, Java and Borneo. Each locality was recorded by geographic positioning system (GPS). All collected specimens were classified and identified based on the following literatures: Fulton (1896), Pilsbry (1900), Laidlawi & Solem (1961) and Solem (1965). The cladistic analysis of shell and genitalia of each species was performed by using Hennig 86 with unweighted, non-additive characters. DNA were extracted, amplified and sequenced. Molecular gene trees from mitochondrial 16S rRNA gene were generated using PAUP. Chloritis siamensis was used as an outgroup. The inferred morphological and molecular phylogeny show the congruent support for the monophyly between the subgenus amphidromus and Syndromus. It also reveals that A. schomburgki seems to have a close affinity to subgenus Amphidromus. Shell morphological characters could not tell the relationship between species in each subgenus. Mitochondrial rRNA sequences provide valuable data for testing the monophyletic and relationships within subgenus