Abstract
Thai limestone karsts are known to contain a rich biodiversity of animals, especially terrestrial snails, but still require further intensive exploration to evaluate their biodiversity. To date, only a few studies on the limestone karst-inhabiting land snail genera have been published. The present work focuses on the species diversity and phylogenetic relationships of the limestone karst-restricted land snail genus Aenigmatoconcha from Thailand, based on comparative morphology and molecular evidence. The results yielded three known species (A. clivicola Tumpeesuwan & Tumpeesuwan, 2017, A. sumonthai Tumpeesuwan & Tumpeesuwan, 2018, and A. mitis (Pfeiffer, 1863) comb. nov.), plus a new species (A. eunetis Pholyotha & Panha sp. nov). The phylogenetic analyses of partial fragments of the mitochondrial cytochrome oxidase c subunit I (COI) gene confirmed the monophyly of all recognized species and congruence with the traditional morphology-based species designations. Average uncorrected p-distances of COI sequences between species were 9.7–12.0% and within species were 0.2–4.2%. This study also provides the re-description of penial sculpture, penial sheath, flagellum, penial caecum, and mantle lobe morphology that were neglected from the type species description. The present discovery of a new species increases the known diversity of Thai land snails and will support the conservation planning to protect karst biodiversity.
Highlights
Situated in the Indo-Burmese biodiversity hotspot region, Thailand is one of the most bio-diverse countries in mainland Southeast Asia (Myers et al 2000)
The COI dataset did not resolve the phylogenetic relationships among Aenigmatoconcha, Chalepotaxis, and Sophina (Fig. 2), yet it did retrieve each of the four Aenigmatoconcha species as well-supported clades (Fig. 2)
The phylogenetic relationships among Aenigmatoconcha, Sophina and Chalepotaxis remain unresolved, the genital characters of both groups of Aenigmatoconcha were clearly distinct from Sophina and Chalepotaxis
Summary
Situated in the Indo-Burmese biodiversity hotspot region, Thailand is one of the most bio-diverse countries in mainland Southeast Asia (Myers et al 2000). Aenigmatoconcha was recently described including its genital and radula features, several other diagnostic characters have never been mentioned for either species. These key characters are important for identification at both the specific and generic levels. As the type localities of the two known Aenigmatoconcha species are distantly separated by approximately 900 km, it is expected that Aenigmatoconcha species may occur in limestone karts along the Tenasserim Range from North to South Thailand (Naggs et al 2006; Ridd et al 2011; Latinne et al 2013; Gardner et al 2015)
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