Krobylos sinensis 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 : 48-51

Taxon classification Animalia Pulmonata Hypselostomatidae

Krobylos sinensis Pall-Gergely & Hunyadi sp. n. Figures 9, 10

Type material.

China, Guangxi (广西), Bose Shi (百色市), Leye Xian (乐业县), Chuandong Tiankeng Scenic Area (穿洞天坑景区), inner cliffs of the dolina, 1290 m, 24°48.430'N, 106° 29.277'E, leg. Hunyadi, A. & Szekeres, M., 09.09.2013., HNHM 99446 (holotype), HNHM 99447/1 (paratype), SMF 346522/1 paratype, HA/12 paratypes + 2 juvenile shells (not paratypes), PGB/1; China, Guangxi (广西), Hechi Shi (河池市), Tiane Xian (天峨县), Qimu Xiang (豈暮乡), cross towards Lahao Yan (拉号岩), 600 m, 24°51.130'N, 107°11.670'E, leg. Hunyadi, A. & Szekeres, M., 12.09.2013., HA/3 paratypes; China, Guangxi (广西), Hechi Shi (河池市), Huanjiang Xian (南丹县), cliffs above Dongning (峒宁) Village S of the Mulun Nature Reserve (木论国家级自然保护区), 530 m, 25°5.970'N, 107°57.639'E, leg. Hunyadi, A. & Szekeres, M., 17.09.2013., HA/3 paratypes.

Diagnosis.

A large Krobylos species with conical spire, rounded, regularly coiled whorls, large oval-shaped aperture, adnate parietal side and very weak indication of spiral striae on its dorsal surface.

Description.

Shell small, usually wider than high, only a single specimen from the Mulun Nature Reserve had the shell height and the shell diameter both measuring 2.7 mm; the 3.75-4.25 whorls are separated by a well-defined deep suture; whorls weakly angular, especially the penultimate whorl; protoconch light brownish purple, glossy, no notable sculpture visible; teleoconch light to dark purple, or pinkish, with blunt, irregularly course wrinkles; no spiral lines are visible under the microscope, but the SEM images revealed a hint of spiral striation on the lower half of each whorl (except for the last one); umbilicus open, narrow, (from ventral view), only its edge is covered by the peristome; aperture wide with its parietal part adnate to the penultimate whorl; peristome sharp, not thickened, not expanded nor reflexed; aperture reflected at columellar margin such that it covers the edge of the umbilicus.

Measurements

(in mm): SH = 2.2-2.7, SW = 2.5-3 (n = 13 from all populations).

Differential diagnosis.

Krobylos sinensis sp. n. differs from Tonkinospira depressa ( Jaeckel 1950) by the larger size, rounded whorls and the absence of spiral sculpture on the upper sides of the whorls. The aperture of Tonkinospira defixa (Bavay & Dautzenberg, 1912) is not adnate, and its shell is much smaller than Krobylos sinensis sp. n. Tonkinospira pulverea (Bavay & Dautzenberg, 1909) has more rounded whorls and the entire surface is regularly spirally striated. Tonkinospira pauperrima (Bavay & amp; Dautzenberg, 1909) has a much more elevated spire, narrower umbilicus and stronger spiral striae.

Krobylos maehongsonensis Panha & Burch, 1999 has a higher spire, a relatively larger aperture, sharper keel, weaker radial growth lines and more bulging whorls from dorsal view (in Krobylos sinensis sp. n. the whorls are ventrally more flat). Krobylos kangkoy Panha & Burch, 2004 (in Panha et al. 2004) has a much narrower umbilicus than the new species. Krobylos pomjuk Panha & Burch, 1999 also has a narrower umbilicus and a more depressed shell with a wider aperture. It is much smaller than Krobylos sinensis sp. n. Similarly as small, Krobylos takensis Panha & Burch, 2004 (in Panha et al. 2004) has a higher spire and more angled whorls. Krobylos tampla is even smaller bearing a narrower umbilicus. The aperture of Krobylos veruwan Panha & Burch, 2004 (in Panha et al. 2004) has a low palatal ridge, which is missing in Krobylos sinensis sp. n. Moreover, Krobylos veruwan is much smaller than Krobylos sinensis sp. n. and has a narrower umbilicus. Pyramidula laosensis Saurin 1953, which also likely also belongs to Krobylos , shows increased bulging whorls and a more pronounced closure of the umbilicus by the peristome.

Etymology.

The species is named after China, the country of its type locality.

Type locality.

China, Guangxi (广西), Bose Shi (百色市), Leye Xian (乐业县), Chuandong Tiankeng Scenic Area (穿洞天坑景区), inner cliffs of the dolina, 1290 m, 24°48.430'N, 106° 29.277'E.

Distribution.

Krobylos sinensis sp. n. has been found in three different localities in northern Guangxi Province (Figure 13). See also remarks on the distinctness of Krobylos and Tonkinospira .

Ecology.

Empty shells of this new species have been found in a soil sample at the base of large limestone rocks. It probably lives under stones and inside crevices.

Conservation status.

Krobylos sinensis sp. n. is reported from three sites in this study. This species may inhabit similar habitats in the same geographic area. At the moment, on a global scale, its distribution is likely limited to less than 5 sites, therefore these vulnerable narrow range endemics warrant conservation priority (Vu D2) in conjunction with the Guidelines for the IUCN Red List ( IUCN Standards and Petitions Subcommittee 2014).

Remarks.

Krobylos was described as a group of toothless snails entirely lacking superficial microstructure ( Panha and Burch 1999). Tonkinospira , on the other hand, has prominent spiral microsculpture over the entire surface. In this respect, Krobylos sinensis sp. n. is intermediate, because it has only very slight indication of spiral striae on the lower half of the whorls. This spiral sculpture is very faint or not visible under the microscope, but detectable using SEM images. We provisionally place Krobylos sinensis sp. n. in the genus Krobylos because of the very weak spiral striae. However, we remark that the distinctness of the genera Krobylos and Tonkinospira requires further study. Krobylos sinensis sp. n. is the only species assigned to Krobylos reported outside of Thailand. However, " Pyramidula " laosensis might also belong to the same genus.