Angustopila fabella Pall-Gergely & Hunyadi

Pall-Gergely, Barna, Hunyadi, Andras, Jochum, Adrienne & Asami, Takahiro, 2015, Seven new hypselostomatid species from China, including some of the world's smallest land snails (Gastropoda, Pulmonata, Orthurethra), ZooKeys 523, pp. 31-62 : 33-36

Taxon classification Animalia Pulmonata Hypselostomatidae

Angustopila fabella Pall-Gergely & Hunyadi sp. n. Figure 2

Type material.

China, Guangxi (广西), Chongzuo Shi (崇左市), Longzhou Xian (龙州县), cliffs north of Lenglei (楞垒), north of the Nonggang Nature Reserve (弄岗国家级自然保护区), 220 m, 22°29.161'N, 106°57.357'E, leg. Hunyadi, A. & Szekeres, M., 23.09.2013., HNHM 99436 (holotype), HNHM 99437/2 (figured paratypes), SMF 346520/1 paratype, HA/38 paratypes + 2 juvenile shells (not paratypes), PGB/1 paratype.

Diagnosis.

A tiny, trigonal-shaped species with a rather rounded, slightly bean-shaped aperture bearing a well-developed parietal tooth.

Description.

Shell minute, light grey, bluntly trigonal; protoconch consists of slightly more than 1.25 whorls, protoconch microstructure finely pitted and granular with a powdery superficial texture, the granular microstructure collectively radiates from the nuclear whorl and ceases at the second; teleoconch finely reticulate with irregularly-spaced radial growth lines crossed by rows of microscopic spiral threads; the 4.5-4.75 whorls are separated by a deep suture; whorls shouldered; aperture slightly oblique to shell axis; umbilical zone highly reticulate, umbilicus deep, relatively narrow; aperture heart-shaped; peristome slightly expanded, not reflected; parietal callus well-developed, very slightly adnate to the penultimate whorl; parietal tooth prominent, thick and long; no other dentition is present. Body whorl bulges beyond aperture (side view) by ca. 1/7 the max. breadth of the shell. Apertural lip tilted slightly back with fine creases behind the peristome (side view).

Measurements

(in mm): SH = 0.86-1.02, SW = 0.88-1, AH = 0.34-0.4, AW = 0.36-0.41 (n = 20). See also Tables 1 and 2.

Differential diagnosis.

Angustopila fabella sp. n. is most similar to Angustopila tamlod in shape and form. However, in addition to the parietal denticle, Angustopila tamlod has a small, low palatal plica just opposite the parietal denticle. Angustopila dominikae sp. n. is smaller, has a globular shell (conical in Angustopila fabella sp. n.) and possesses two apertural denticles with an additional tubercle on the parietal denticle. A single parietal denticle is present in Angustopila fabella sp. n. See also Angustopila subelevata sp. n. and Angustopila szekeresi sp. n.

Etymology.

The name, fabella, (Latin: little bean) refers to the bean-shaped aperture.

Type locality.

China, Guangxi (广西), Chongzuo Shi (崇左市), Longzhou Xian (龙州县), cliffs north of Lenglei (楞垒), north of the Nonggang Nature Reserve (弄岗国家级自然保护区), 220 m, 22°29.161'N, 106°57.357'E.

Distribution.

Angustopila fabella sp. n. is known from the type locality only (Figure 13).

Ecology.

Empty shells of this new species were found in a soil sample at the base of large limestone rocks. It likely lives on limestone walls as do other similar hypselostomatid species recorded by Panha and Burch (2005).

Conservation status.

Empty shells have been collected from a soil sample at the type locality. Therefore, knowledge is very limited for evaluating its conservation status. Since the species is known from one site only, it is evaluated as Critically Endangered (CR) under IUCN criteria ( IUCN 2014). Quarrying is quoted as the main threat to similar limestone habitats. However, no ongoing threats to the type locality are known at the moment.