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

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).

本研究针对富潘山脉（Phu Phan mountain range）的陆生蜗牛物种多样性、分布格局及其与生境的关联展开调查。本次调查共采集、分类并鉴定出陆生蜗牛2个亚纲、15个科、22个属及26个物种，其中球形富潘蜗牛（Phuphania globosa）被描述为全新的属与物种。本次记录的15个蜗牛科中，优势类群依次为环口螺科（Cyclophoridae，3种）、阿勇蛞蝓科（Ariophantidae，4种）与巴蜗牛科（Camaenidae，5种）。有9个物种见于干燥龙脑香林、落叶混交林与干燥常绿林这3种林型中，分别为伴生环口螺（Cyclophorus consociatus）、喜拉平圆螺（管圆螺亚属，Cyclotus (Siphonocyclotus) hinlapensis）、温氏巨管螺（Quantula weinkauffiana）、球形富潘蜗牛（Phuphania globosa）、暹罗大蜗牛（Megaustenia siamensis）、鲜明半蛞蝓（Hemiplecta distincta）、灿烂沙丽卡螺（Sarika resplendens）、吉氏两栖蜗牛（两栖蜗牛亚属，Amphidromus (Amphidromus) givenchyi）以及暹罗假柱螺（Giardia亚属，Pseudobuliminus (Giardia) siamensis）。另有4个物种同时分布于干燥龙脑香林与落叶混交林，分别为条斑两栖蜗牛（Syndromus亚属，Amphidromus (Syndromus) zebrinus）、泰国螺属未定种（Thaitropis sp.）、森氏螺属未定种（Semperula sp.）以及褐云玛瑙螺（Lissachatina亚属，Achatina (Lissachatina) fulica）。另有3个物种同时分布于落叶混交林与干燥常绿林，分别为环口螺属未定种（Cyclophorus sp.）、前鳃螺属未定种（Prosopeas sp.）以及丹氏半蛞蝓（Hemiplecta danae）。另有3个物种仅分布于干燥龙脑香林，分别为细毛绿螺（毛绿螺亚属，Chloritis (Trichochloritis) tenella）、头状盖螺（盖螺亚属，Ganesella (Ganesella) capitium）以及Trochomorpha属未定种（Trochomorpha sp.）。另有7个物种仅见于落叶混交林，分别为蛹螺属未定种（Pupina sp.）、施氏两栖蜗牛右旋变种（Amphidromus (Amphidromus) schomburgki dextrochlorus，原文缩写为A. (A.) schomburgki dextrochlorus）、透明螺属未定种（Vitrinopsis sp.）、马滕斯帕玛蜗牛（Parmarion martensi）、杜尔加螺属未定种（Durgella sp.）、暹罗隐带螺（Cryptozona siamensis）以及锐眼螺属未定种（Oxychilus sp.）。本研究在180个100×100米的重复样地中共计记录到26种陆生蜗牛。每个样地的平均物种数与平均个体丰度分别为5.59±2.78种与76.57±33.60号标本。陆生蜗牛的物种多样性以落叶混交林最高（1.6566），其次为干燥常绿林（1.5600），干燥龙脑香林最低（1.3838）。个体丰度则以干燥常绿林最高（81±30），落叶混交林居中（91±41），干燥龙脑香林最低（61±17）。3种林型间的物种相似性指数存在小幅差异。3种林型的优势度指数均较低，表明这3种林型中均不存在绝对优势的蜗牛物种。样地内的物种总数以落叶混交林最高，均值为7.05±3.34种，干燥龙脑香林最低，均值为4.75±1.83种，差异具有统计学意义。多数蜗牛的壳体呈扁平状（壳高/壳宽比<1），主要栖息于地表生境，仅前鳃螺属未定种（Prosopeas sp.）具有高旋壳体。而多数具有高旋壳体的蜗牛则栖息于树栖生境。富潘山脉陆生蜗牛的壳体形态与其栖息高度呈显著正相关（决定系数R²=0.5817，P<0.05）。