Species diversity, distribution and habitat relationships of terrestrial snails on the Phu Phan mountain range of Norteastern Thailand

Abstract

Species diversity, distribution and habitat relationship of land snails were investigated on the Phu Phan mountain range. Two subclasses, 15 families, 22 genera, and 26 species of land snails were collected, classified and identified. Phuphania globosa was described as a new genus and new species. Fifteen snail families were represented, of which the three most prominent were the Cyclophoridae (3 species), Ariophantidae (4 species) and Camaenidae (5 species). Nine species; Cyclophorus consociatus, Cyclotus (Siphonocyclotus) hinlapensis, Quantula weinkauffiana, Phuphania globosa, Megaustenia siamensis, Hemiplecta distincta, Sarika resplendens, Amphidromus (Amphidromus) givenchyi and Pseudobuliminus (Giardia) siamensis were found in the three forest types represented in the dry dipterocarp forest, mixed deciduous forest and dry evergreen forest. Four species were found both in dry dipterocarp forest and mixed deciduous forest; Amphidromus (Syndromus) zebrinus, Thaitropis sp., Semperula sp. and Achatina (Lissachatina) fulica. Three species were recorded both in mixed deciduous forest and dry evergreen forest Cyclophorus sp., Prosopeas sp., and Hemiplecta danae. Three species Chloritis (Trichochloritis) tenella, Ganesella (Ganesella) capitium and Trochomorpha sp. occurred only in dry dipterocarp forest. Seven species; Pupina sp., A. (A.) schomburgki dextrochlorus, Vitrinopsis sp., Parmarion martensi, Durgella sp., Cryptozona siamensis and Oxychilus sp. were found only in mixed deciduous forest. Twenty-six land snail species were recorded in one hundred and eighty replicated plots (100 x 100 m) during the study. Mean number of species and mean land snails abundance were 5.59+-2.78 species and 76.57+-33.60 specimens per plot, respectively. The highest land snail diversity was recorded in mixed deciduous forest (1.6566), the second was in dry evergreen forest (1.5600) and the lowest was in dry dipterocarp forest (1.3838). The abundance was highest in dry evergreen forest (81+-30), intermediate abundance was in mixed deciduous forest (91+-41) and the lowest was in dry dipterocarp forest (61+-17). The similarity index among three forest types was slightly different. The index of dominance in three forest types was low. It indicates that there is no dominant snail species in three forest types. The total number of species per plot was significantly highest on mixed deciduous forest, (7.05+-3.34) and the lowest in dry dipterocarp forest (4.75+-1.83). Most snails which have flat shell (h/d ratio < 1) predominate in the ground dweller habitats, only Prosopeas sp. has tall-spired shells. Most snail possessions high spire shells live in tree dweller habitats. There was positive correlation between shell shape and habitat height of land snails on the Phu Phan mountain range (R[superscript 2] = 0.5817; P < 0.05).