Hypselostoma socialis 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 : 43-47

Taxon classification Animalia Pulmonata Hypselostomatidae

Hypselostoma socialis Pall-Gergely & Hunyadi sp. n. Figures 7, 8 A–E

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 99442 (holotype), HNHM 99443/3 (figured paratypes), SMF 346521/1 paratype, HA/15 paratypes + 4 juvenile shells (not paratypes), PGB/1.

Diagnosis.

Shell spire conical, shell turban-shaped with tumid body whorl and broadly set, deep umbilicus; tubus detached; aperture rounded with wide sinulus, the upper parietal lamella dips to the right; aperture with a parietal lamella, one columellar and two palatal teeth; parietal lamella long and depressed, Z-shaped.

Description.

Shell minute, whitish/light grey, conical with enlarged body whorl; protoconch consists of 1.5 whorls, finely pitted, with very slight indication of spiral lines; teleoconch reticulated with fine, regularly spirally striate microstructure intersected with irregular radial lines; the 5.5 whorls are separated by deep suture; whorls horizontally positioned, rounded; aperture oblique to shell axis; umbilicus deep, wide, especially at the last whorl; aperture free from the penultimate whorl, rounded with wide sinulus (area isolated by the parietal and upper palatal lamellae); sinulus horizontally oriented (apertural view); peristome slightly expanded, not reflected, with relatively sharp edge; (side view), the horizontally directed tuba is deflected downwards in alignment with the body whorl; four teeth recessed within aperture; only the ridge-like angulo-parietal lamella reaches the peristome, the others are situated deeper; angulo-parietal lamella moderately long, its end is visible from a straight view into the aperture; it is interrupted, consisting of an anterior section (situated closer to the peristome) and a slightly longer posterior section (situated deeper in the aperture); the anterior section is strongly bent toward the sinulus, its tip nearly touches the tip of the upper palatal fold; the posterior part of the angulo-parietal lamella is less strongly bent than the anterior portion, only its anterior part is bent toward the upper palatal lamella; the angulo-parietal and the upper palatal lamellae follow each other; the angulo-parietal lamella has a depressed Z-shape when observed after breaking off the lower part of the aperture; the anterior part of the angulo-parietal lamella is possibly homologous with the parietal lamella of other hypselostomatid taxa, while the second portion might be homologous with the angular lamella, or vice versa; columellar and lower palatal lamellae are elevated, blunt and short, they are about the same length and are visible through the semi-transparent shell; the upper palatal fold is also of similar length, its posterior end runs parallel with the lower palatal fold; the tip of the upper palatal fold nearly touches the tip of the angulo-parietal lamella.

Measurements

(in mm): SH = 1.14-1.34, SW = 1.22-1.36, AH = 0.43-0.5, AW = 0.49-0.53 (n = 10). See also Tables 9 and 10.

Differential diagnosis.

Hypselostoma lacrima sp. n. and Hypselostoma socialis sp. n. are the only species of Hypselostoma known from China. Some Chinese species formerly included in Hypselostoma have been reassigned to other genera ( Yen 1939). Hypselostoma dilatatum Benthem Jutting 1962, Hypselostoma rupestre Benthem Jutting 1962 and Hypselostoma annamiticum Möllendorff, 1900 are approximately two times larger than Hypselostoma lacrima sp. n. and Hypselostoma socialis sp. n., and have more (5-8) apertural barriers. Hypselostoma laidlawi from Malaysia is similar in size to Hypselostoma lacrima sp. n. and Hypselostoma socialis sp. n., but it has a much narrower umbilicus and five apertural barriers.

Hypselostoma lacrima sp. n. has a much wider umbilicus than Hypselostoma socialis sp. n. Moreover, the spiral lines on the protoconch of Hypselostoma socialis sp. n. are weaker than those of the other species. The aperture of Hypselostoma lacrima sp. n. is heart-shaped with the sinulus vertically oriented, whereas the aperture of Hypselostoma socialis sp. n. is semi-quadrate and rounded with its sinulus positioned horizontally. The parietal lamella of Hypselostoma socialis sp. n. is interrupted and short (depressed Z-shaped), whereas that of Hypselostoma lacrima sp. n. is longer and straighter, lacking the conspicuous blade-like ridge visible in Hypselostoma socialis sp. n.

Etymology.

The name, socialis, (Latin: social) refers to the fact that this new species has been found together with three Angustopila species.

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.

Hypselostoma socialis sp. n. 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.

See under Hypselostoma lacrima sp. n.