A review of the microgastropod genus Systenostoma Bavay & Dautzenberg, 1908 and a new subterranean species from China (Gastropoda, Pulmonata, Hypselostomatidae) Author Jochum, Adrienne Author Slapnik, Rajko Author Kampschulte, Marian Author Martels, Gunhild Author Heneka, Markus Author Pall-Gergely, Barna text ZooKeys 2014 410 23 40 http://dx.doi.org/10.3897/zookeys.410.7488 journal article http://dx.doi.org/10.3897/zookeys.410.7488 1313-2970-410-23 E4C040C1939640F18C12D9518F59F668 E4C040C1939640F18C12D9518F59F668 Angustopila huoyani Jochum, Slapnik & Pall-Gergely sp. n. Figure 4-5, Video 1 Type material. China, Hunan, Longshan (龙山县), Huoyan (火焰), Feihu Dong (飞虎洞), ( 29°12.53'N , 109°18.37'E , 550 m alt.), soil, leg. Verovnik, 13.04.1997, MCSMNH 50312/1 (holotype), MCSMNH 50312/2-9 (8 paratypes). Diagnosis. A tiny, thin-shelled conical snail with very deep and narrow umbilicus, 5 shouldered whorls and two apertural denticles (parietal and palatal). Description. Shell thin, greyish white, semi opaque; conical, widest at its base, with a homogeneous powdery superficial texture and regularly increasing, shouldered whorls separated by deep suture; smooth with no notable spiral or radial sculpture. It is characterized by very fine irregular axial lamellae and reticulating microgranules producing the powdery superficial texture; protoconch shows reticulating granules and recognisable radial lines only at the upper part of the first whorl; aperture semi-circular, slightly oblique from ventral view; peristome very slightly thickened and reflexed; parietal callus adnate (attached to the penultimate whorl); aperture with two well-developed but short denticles, one on the parietal and the other on the palatal side; umbilicus very deep and narrow. Video 1. Micro-CT Video of Angustopila huoyani sp. n. Video: Markus Heneka. http://www.pensoft.net/J_FILES/1/articles/7488/Jochum_Video_1.avi Measurements. See Table 1. Table 1. Shell measurements (mm) for Angustopila huoyani sp. n. from the type locality. SH - shell height, SW - shell width, AH - aperture height, AW - aperture width, SW/ SHx 100 - shell width shared with shell height and multiplied 100, AW/ AHx 100 - aperture width shared with aperture height and multiplied 100).

SH	SW	AH	AW	SW/ SHx 100	AW/ AHx 100	specimen

Table 2. Average. minimum value (min). maximum value (max). variance of values (var) and standard deviation of a set of values (stdev) for Angustopila huoyani sp. n. N = 30.

SH	SW	AH	AW	SW/ SHx 100	AW/ AHx 100

Differential diagnosis. Tonkinospira defixa , Tonkinospira pulverea , Tonkinospira pauperrima and Tonkinospira depressa are much larger than the new species, have reticulated sculpture and lack denticles in the aperture. Moreover, Tonkinospira defixa has a more depressed spire, fewer whorls, wider umbilicus and slightly keeled body whorl; Tonkinospira pulverea has fewer whorls, a comparatively larger aperture, somewhat keeled, wider body whorl and its umbilicus is partly closed by the apertural margin; Tonkinospira pauperrima shows increased bulging in whorl configuration; Tonkinospira depressa has a lower spire, slightly keeled body whorl and a large aperture without denticles. Hypselostoma (?) edentata also lacks denticles in the aperture and possesses a very wide, laterally compressed body whorl. Angustopila tamlod , the most similar species, is slightly smaller, has fewer whorls, wider umbilicus and obvious spiral striation on the teleoconch. Angustopila concava has a much wider body whorl than that of Angustopila huoyani , has weaker apertural denticles and prominent spiral sculpture. Angustopila elevata has no denticles in the aperture and possesses a wider umbilicus and spirally striated shell. Angustopila neglecta (see also notes under that species) has a wider umbilicus and more rapidly growing whorls, resulting in a comparatively wider body whorl than in the new species. Angustopila neglecta also has spiral lines on the shell and its sinulus is wider. Shell characters and ecological information of all Angustopila species are presented in Table 3. Table 3. The most important morphological traits and ecological information for Angustopila huoyani sp. n. and its congeners extracted from the literature.

Angustopila concava	Angustopila elevata	Angustopila huoyani sp. n.	Angustopila neglecta	Angustopila tamlod
Shell colour
Teleoconch sculpture
Protoconch sculpture
Aperture shape/ peristome
Aperture dentition
Umbilicus
Whorl number
Shell height (mm)
Ecology

Etymology. The new species is named after the Gorges of Huoyan, where the type locality is located. Distribution. The new species is known from the type locality only. Ecology. The new species is known only from the Feihu Dong ("Cave of the Wind Tiger"). Angustopila huoyani were culled from samples of rocky-loamy substrate collected in the entrance corridor of the cave. It is highly likely that the distribution of Angustopila huoyani sp. n. is restricted to this cave only. Conservational status. Our knowledge of the biogeography of the genus is very limited. However, we assume that most Angustopila , especially the cave-dwelling species, are narrow-range endemics. Since extreme endemism always makes species vulnerable to human encroachment, this species warrants conservation priority. Currently, no direct threats are known.