Angustopila Jochum, Slapnik & Pall-Gergely , 2014

Pall-Gergely, Barna, Hunyadi, Andras, Vermeulen, Jaap J., Grego, Jozef, Sutcharit, Chirasak, Reischuetz, Alexander, Dumrongrojwattana, Pongrat, Botta-Dukat, Zoltan, Oerstan, Aydin, Fekete, Judit & Jochum, Adrienne, 2023, Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae), ZooKeys 1147, pp. 1-177 : 1

Genus Angustopila Jochum, Slapnik & Pall-Gergely, 2014

Angustopila Jochum, Slapnik & Páll-Gergely, 2014 in Jochum et al. 2014: 26.

Type species.

Systenostoma tamlod Panha & Burch, 2002, by original designation.

Content.

53 species and one subspecies: A. akrodon Páll-Gergely & Hunyadi, sp. nov., A. apiaria Páll-Gergely & Hunyadi, sp. nov., A. apiostoma Páll-Gergely & Vermeulen, sp. nov., A. apokritodon Páll-Gergely & Hunyadi, sp. nov., A. antidomedon Páll-Gergely & Hunyadi, sp. nov., A. babel Páll-Gergely & Vermeulen, sp. nov., A. bathyodon Páll-Gergely & Hunyadi, sp. nov., A. bidentata Páll-Gergely & Jochum, sp. nov., A. cavicola Páll-Gergely & Dumrongrojwattana, sp. nov., A. cicatricosa Páll-Gergely & Vermeulen, sp. nov., A. concava (Thompson & Upatham, 1997), A. coprologos coprologos Páll-Gergely, Jochum & Hunyadi, 2022, A. coprologos uninodus Páll-Gergely & Grego, ssp. nov., A. dominikae Páll-Gergely & Hunyadi, 2015, A. elevata (Thompson & Upatham, 1997), A. erawanica Páll-Gergely & Dumrongrojwattana, sp. nov., A. fabella Páll-Gergely & Hunyadi, 2015, A. fratermajor Páll-Gergely & Vermeulen, sp. nov., A. fraterminor Páll-Gergely & Vermeulen, sp. nov., A. gracilis Páll-Gergely & Hunyadi, sp. nov., A. halongensis Páll-Gergely & Vermeulen, sp. nov., A. huoyani Jochum, Slapnik & Páll-Gergely, 2014, A. hyron Páll-Gergely & Vermeulen, sp. nov., A. maasseni Páll-Gergely & Vermeulen, sp. nov., A. majuscula Páll-Gergely & Hunyadi, sp. nov., A. margaritarion Páll-Gergely & Hunyadi, sp. nov., A. megastoma Páll-Gergely & Vermeulen, sp. nov., A. milium (Benson, 1853), A. occidentalis Páll-Gergely & Hunyadi, sp. nov., A. oostoma Páll-Gergely & Vermeulen, sp. nov., A. pallgergelyi Dumrongrojwattana, Chuenit & Wongkamhaeng, 2021, A. papaver Páll-Gergely & Hunyadi, sp. nov., A. parallela Páll-Gergely & Hunyadi, sp. nov., A. prolixa Páll-Gergely & Hunyadi, sp. nov., A. psammion Páll-Gergely, Vermeulen & Anker, 2022, A. pusilla Páll-Gergely & Hunyadi, sp. nov., A. pustulata Páll-Gergely & Hunyadi, sp. nov., A. quadridens Páll-Gergely & Vermeulen, sp. nov., A. rara Páll-Gergely & Hunyadi, sp. nov., A. reticulata Páll-Gergely & Hunyadi, sp. nov., A. somsaki Páll-Gergely & Hunyadi, sp. nov., A. steffeki Páll-Gergely & Grego, sp. nov., A. szekeresi Páll-Gergely & Hunyadi, 2015, A. thersites Páll-Gergely & Vermeulen, sp. nov., A. tonkinospiroides Páll-Gergely & Vermeulen, sp. nov., A. tamlod (Panha & Burch, 2002), A. tetradon Páll-Gergely & Hunyadi, sp. nov., A. tridentata Páll-Gergely & Hunyadi, sp. nov., A. tweediei Páll-Gergely & Hunyadi, sp. nov., A. uvula Páll-Gergely & Hunyadi, sp. nov., A. vandevenderi Páll-Gergely & Jochum, sp. nov., A. vitrina Páll-Gergely & Hunyadi, sp. nov., A. vomer Páll-Gergely & Hunyadi, sp. nov., A. werneri Páll-Gergely & Hunyadi, sp. nov. (Fig. 7 , Table 1 ).

Diagnosis.

Shell minute (diameter: 0.6-1.24 mm, height: 0.46-1.31 mm), transparent when fresh or whitish (practically colourless); conical, concave-conical, conical-globular, globular or depressed-globular, whorls mostly regularly growing, body whorl never detached (although the parietal callus may project from the penultimate whorl); protoconch with or without spiral striae; body whorl with 10-20 (exceptionally up to 22) spiral striae counted from standard apertural view in line with the shell axis; occasionally spiral lines are lacking; peristome expanded, not reflected, aperture with 0-5 teeth, parietal wall with or without 1 tooth; parietal tooth usually elongated, reaches or does not reach parietal callus; other denticles short, situated on or close to peristome; umbilicus open, 14-38% of shell width.

Differential diagnosis.

So far, the diagnosis was based on 13 species. Now that there are 53 known Angustopila species, the morphological variability of the genus considerably increased. Even with so many species included, the genus appears “compact” in terms of morphological characters, and in most cases, it is not difficult to identify shells to the genus level.

Regarding apertural denticles, Angustopila is very conservative. All non-parietal apertural barriers are short and situated on or very close to the peristome. The only exception is Angustopila apiaria sp. nov., in which the palatal and subcolumellar teeth are elongated into the aperture. This, and the relatively disjunct distribution in Central Vietnam may indicate that it warrants a genus of its own.

Amongst Southeast Asian Hypselostomatidae , Dentisphaera Páll-Gergely & Jochum, 2017, Clostophis Benson, 1860 and Tonkinospira Jochum, Slapnik & Páll-Gergely, 2014 are similar to Angustopila in the tiny, colourless shells. Dentisphaera possesses an angular and parietal tooth, which readily distinguishes it from Angustopila , which always has a single tooth on the parietal side. Although Clostophis (see Páll-Gergely et al. 2020) and Tonkinospira (see Páll-Gergely et al. 2019) are possibly synonyms ( Páll-Gergely and Hunyadi 2022), discussion however, is beyond the scope of the present paper. Both are characterised by shells larger than 1.2 mm (typically approximately 2 mm). In samples where both Angustopila and Tonkinospira / Clostophis species occur, it is already clear from the size groups, that Angustopila are distinct due to their small size. Moreover, the spiral striation of Tonkinospira / Clostophis is usually denser than that of Angustopila (22-36 ribs on the body whorl in apertural view, compared to usually 10-20 in Angustopila ). However, there are three species from the Halong Bay Area ( A. megastoma sp. nov., A. thersites sp. nov., and A. tonkinospiroides sp. nov.) that resemble several Tonkinospira species in the irregular growth of the whorls (especially the dominant body whorl), the comparatively large, mostly toothless aperture, and the relatively dense spiral striae. However, due to their small size, we treat these three species as Angustopila , although we remark that future examinations should address this issue.

Habitat.

Only three species, A. cavicola sp. nov., A. erawanica sp. nov., and A. pallgergelyi (see Dumrongrojwattana et al. 2021) have ever been collected alive, and with no exception in caves, far from the cave entrance, but occasionally also found around the cave entrance. Similarly, empty shells of several other species have only been found in soil samples collected inside caves. However, the majority of shells were found in soil samples collected at the base of large limestone rocks. In is unknown whether those shells have been washed out of caves and deep crevices, or if the living snails live outside of caves. Generally, Angustopila species most probably inhabit moist, deep limestone crevices and caves, close to (or on) root systems.

Soil samples containing Angustopila shells collected in and outside of caves, are mostly dominated by diplommatinids and hydrocenids, while shells of other small-bodied snails (hypselostomatids, alycaeids, diapherids, ‘subulinids’, Microcystina Mörch, 1872, Kaliella W. T. Blanford, 1863, Philalanka Godwin-Austen, 1898, locally assimineids) are also often included, but generally, in smaller quantities.

Conservation, threats.

The majority of Angustopila species are single-site or narrow range endemics. This will not change much, even when more detailed sampling is conducted in the region. Thus, destruction of a habitat of an Angustopila species can easily lead to the disappearance of a species. The most tangible threats to their preferred habitats are quarrying and modifying caves for tourism and recreational purposes.

Distribution.

Most species are known in Southeast Asia (entire Thailand, southern Shan and Kayah states of Myanmar, northern Laos and northern and central Vietnam). A few species are known from the Chinese province of Guangxi and a single record from Hunan. A single species from the Indian state of Meghalaya indicates that the genus is present in the south-eastern Himalaya (Fig. 8 ).

Figures

Figure 7. a A. coprologos coprologos Pall-Gergely, Jochum & Hunyadi, 2022 b A. somsaki Pall-Gergely & Hunyadi, sp. nov. c A. hyron Pall-Gergely & Vermeulen, sp. nov. d A. papaver Pall-Gergely & Hunyadi, sp. nov. e A. maasseni Pall-Gergely & Vermeulen, sp. nov. f A. prolixa Pall-Gergely & Hunyadi, sp. nov. g A. psammion Pall-Gergely, Vermeulen & Anker, 2022 h A. pallgergelyi Dumrongrojwattana, Chuenit & Wongkamhaeng, 2021 i A. pusilla Pall-Gergely & Hunyadi, sp. nov. j A. steffeki Pall-Gergely & Grego, sp. nov. k A. cicatricosa Pall-Gergely & Vermeulen, sp. nov. l A. fraterminor Pall-Gergely & Vermeulen, sp. nov. m A. bathyodon Pall-Gergely & Hunyadi, sp. nov. n A. rara Pall-Gergely & Hunyadi, sp. nov. o A. apiaria Pall-Gergely & Hunyadi, sp. nov. p A. margaritarion Pall-Gergely & Hunyadi, sp. nov. q A. apiostoma Pall-Gergely & Vermeulen, sp. nov. r A. szekeresi Pall-Gergely & Hunyadi, 2015 s A. akrodon Pall-Gergely & Hunyadi, sp. nov. t A. apokritodon Pall-Gergely & Hunyadi, sp. nov. u A. oostoma Pall-Gergely & Vermeulen, sp. nov. v A. gracilis Pall-Gergely & Hunyadi, sp. nov. w A. elevata (Thompson & Upatham, 1997) x A. tetradon Pall-Gergely & Hunyadi, sp. nov. y A. megastoma Pall-Gergely & Vermeulen, sp. nov. z A. tridentata Pall-Gergely & Hunyadi, sp. nov. aa A. antidomedon Pall-Gergely & Hunyadi, sp. nov. ab A. vitrina Pall-Gergely & Hunyadi, sp. nov. ac A. uvula Pall-Gergely & Hunyadi, sp. nov. ad A. vandevenderi Pall-Gergely, sp. nov. ae A. vomer Pall-Gergely & Hunyadi, sp. nov. af A. werneri Pall-Gergely & Hunyadi, sp. nov. ag A. thersites Pall-Gergely & Vermeulen, sp. nov. ah A. occidentalis Pall-Gergely & Hunyadi, sp. nov. ai A. pustulata Pall-Gergely & Hunyadi, sp. nov. aj A. tweediei Pall-Gergely & Hunyadi, sp. nov. ak A. cavicola Pall-Gergely & Dumrongrojwattana, sp. nov. al A. reticulata Pall-Gergely & Hunyadi, sp. nov. am A. babel Pall-Gergely & Vermeulen, sp. nov. an A. fratermajor Pall-Gergely & Vermeulen, sp. nov. ao A. fabella Pall-Gergely & Hunyadi, 2015 ap A. dominikae Pall-Gergely & Hunyadi, 2015 aq A. tonkinospiroides Pall-Gergely & Vermeulen, sp. nov. ar A. parallela Pall-Gergely & Hunyadi, sp. nov. as A. quadridens Pall-Gergely & Vermeulen, sp. nov. at A. tamlod (Panha & Burch, 1999) au A. huoyani Jochum, Slapnik & Pall-Gergely, 2014 av A. bidentata Pall-Gergely & Jochum, sp. nov. aw A. majuscula Pall-Gergely & Hunyadi, sp. nov. ax A. concava (Thompson & Upatham, 1997) ay A. halongensis Pall-Gergely & Vermeulen, sp. nov. az A. milium (Benson, 1853) ba A. erawanica Pall-Gergely & Dumrongrojwattana, sp. nov. (Note that only species-level taxa indicated).

Figure 8. Distribution of the genus Angustopila.