Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae)

The Southeast Asian genus Angustopila, currently comprising 13 nominal species, encompasses the world's tiniest land snails. This work shows that there are far more species than previously suspected, and that this genus is in fact, a very speciose group of tiny snails widely distributed in Southeast Asia. Angustopila is revised based on type material of known species as well as 211 samples newly collected in China, Laos, Myanmar, Thailand and Vietnam. Altogether, 53 species and one subspecies are recognised, of which 42 species and subspecies are new to science: A. akrodon Pall-Gergely & Hunyadi, sp. nov., A. apiaria Pall-Gergely & Hunyadi, sp. nov., A. apiostoma Pall-Gergely & Vermeulen, sp. nov., A. apokritodon Pall-Gergely & Hunyadi, sp. nov., A. antidomedon Pall-Gergely & Hunyadi, sp. nov., A. babel Pall-Gergely & Vermeulen, sp. nov., A. bathyodon Pall-Gergely & Hunyadi, sp. nov., A. bidentata Pall-Gergely & Jochum, sp. nov., A. cavicola Pall-Gergely & Dumrongrojwattana, sp. nov., A. cicatricosa Pall-Gergely & Vermeulen, sp. nov., A. coprologos uninodus Pall-Gergely & Grego, ssp. nov., A. erawanica Pall-Gergely & Dumrongrojwattana, sp. nov., A. fratermajor Pall-Gergely & Vermeulen, sp. nov., A. fraterminor Pall-Gergely & Vermeulen, sp. nov., A. gracilis Pall-Gergely & Hunyadi, sp. nov., A. halongensis Pall-Gergely & Vermeulen, sp. nov., A. hyron Pall-Gergely & Vermeulen, sp. nov., A. maasseni Pall-Gergely & Vermeulen, sp. nov., A. majuscula Pall-Gergely & Hunyadi, sp. nov., A. margaritarion Pall-Gergely & Hunyadi, sp. nov., A. megastoma Pall-Gergely & Vermeulen, sp. nov., A. occidentalis Pall-Gergely & Hunyadi, sp. nov., A. oostoma Pall-Gergely & Vermeulen, sp. nov., A. papaver Pall-Gergely & Hunyadi, sp. nov., A. parallela Pall-Gergely & Hunyadi, sp. nov., A. prolixa Pall-Gergely & Hunyadi, sp. nov., A. pusilla Pall-Gergely & Hunyadi, sp. nov., A. pustulata Pall-Gergely & Hunyadi, sp. nov., A. quadridens Pall-Gergely & Vermeulen, sp. nov., A. rara Pall-Gergely & Hunyadi, sp. nov., A. reticulata Pall-Gergely & Hunyadi, sp. nov., A. somsaki Pall-Gergely & Hunyadi, sp. nov., A. steffeki Pall-Gergely & Grego, sp. nov., A. tetradon Pall-Gergely & Hunyadi, sp. nov., A. thersites Pall-Gergely & Vermeulen, sp. nov., A. tonkinospiroides Pall-Gergely & Vermeulen, sp. nov., A. tridentata Pall-Gergely & Hunyadi, sp. nov., A. tweediei Pall-Gergely & Hunyadi, sp. nov., A. uvula Pall-Gergely & Hunyadi, sp. nov., A. vandevenderi Pall-Gergely & Jochum, sp. nov., A. vitrina Pall-Gergely & Hunyadi, sp. nov., A. vomer Pall-Gergely & Hunyadi, sp. nov., A. werneri Pall-Gergely & Hunyadi, sp. nov. Angustopila subelevata Pall-Gergely & Hunyadi, 2015 is moved to the synonymy of Angustopila elevata (F. G. Thompson & Upatham, 1997), and A. singuladentis Inkhavilay & Panha, 2016 is a junior synonym of A. fabella Pall-Gergely & Hunyadi, 2015. Three species, namely A. elevata, A. fabella and A. szekeresi, are widespread over several hundred kilometres while some other species (A. huoyani, A. parallela sp. nov., A. cavicola sp. nov.) are known from just two sites a few hundred kilometres apart. All others are small range or single-site endemics. The reproductive anatomy of A. erawanica sp. nov. is described.

Automated summary

This study reveals that there are more species in the Southeast Asian genus Angustopila than previously known, indicating that it is a widely distributed and speciose group of tiny land snails. By revising the genus based on type material and newly collected samples, a total of 53 species and one subspecies were recognized, with 42 of them being newly discovered. The reproductive anatomy of a newly discovered species, A. erawanica, was also described.