Angustopila szekeresi 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 : 38-42

Taxon classification Animalia Pulmonata Hypselostomatidae

Angustopila szekeresi Pall-Gergely & Hunyadi sp. n. Figure 5

Type material.

China, Guangxi (广西), Hechi Shi (河池市), Bama Xian (巴马县), cliffs at the southern edge of Jiaole Cun (交乐村), 590 m, 24°7.045'N, 107°7.847'E, leg. Hunyadi, A. & Szekeres, M., 10.09.2013., HNHM 99440 (holotype), HNHM 99441/2 (one of them is a figured paratype), HA/6 paratypes.

Diagnosis.

A tiny, trigonal species with rounded aperture having a weak parietal tooth.

Description.

Shell minute, light grey, blunt trigonal; protoconch consists of 1.25 whorls, microstructure finely pitted and granular with a powdery superficial texture, collectively radiating from the nuclear whorl; spiral threads of microstructure transverse the protoconch as well as the teleoconch, a prominent protoconch/teleoconch boundary is present (p/t), which interrupts the very faint rows of finely threaded microstructure; teleoconch finely reticulate with regularly-spaced radial growth striations crossed by rows of microscopic spiral threads; every 8 th– 10th radial line is stronger and visible as growth ridges; the 4-4.25 whorls are separated by a deep suture; whorls rounded; aperture oblique to shell axis; umbilicus deep, relatively narrow; aperture rounded; peristome slightly expanded, not reflected; laterally viewed, the middle section is slightly protruding; parietal callus weak, adnate; parietal tooth weak but present in all specimens.

Measurements

(in mm): SH = 0.88-1.03, SW = 0.77-0.89, AH = 0.33-0.37, AW = 0.35-0.39 (n = 6). See also Tables 5 and 6.

Differential diagnosis.

Sympatric species. Angustopila subelevata sp. n. lacks a parietal tooth, it has a wider umbilicus, a smaller aperture, and its peristome is not adnate. Moreover, the spiral lines on the embryonic whorls are much weaker in Angustopila subelevata sp. n. Angustopila dominikae sp. n. is smaller, has a much more corpulent shell and two teeth in the aperture. Hypselostoma socialis sp. n. is much larger and has four teeth in its aperture.

Non-sympatric species. Angustopila fabella sp. n. has a wider shell, a wider umbilicus, weaker spiral lines on its umbilicus, a stronger parietal tooth and a strong parietal callus (its peristome is not adnate).

Etymology.

Angustopila szekeresi sp. n. is named after Miklós Szekeres, our friend and partner in the field work resulting in all new species reported in this paper.

Type locality.

China, Guangxi (广西), Hechi Shi (河池市), Bama Xian (巴马县), cliffs at the southern edge of Jiaole Cun (交乐村), 590 m, 24°7.045'N, 107°7.847'E.

Distribution.

The new species is known from the type locality only (Figure 13).

Ecology.

As for Angustopila fabella sp. n.

Conservation status.

As for Angustopila fabella sp. n.

Remarks.

The spiral threading on the protoconch is common in the Hypselostomatidae ( Panha and Burch 2005). Noteworthy, is the transition with the p/t boundary in that the microstructure continues in sync with the subsequent whorls. Normally, this phase of ontogenetic development in gastropods [p/t boundary] indicates the transition from the protoconch embryonal stage, whereby the shell structure changes and continues in the teleoconch constructional phase. The continuous protoconch-teleoconch microstructural condition here suggests likely progenesis in these snails.