Hypselostoma lacrima 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 : 42

Taxon classification Animalia Pulmonata Hypselostomatidae

Hypselostoma lacrima Pall-Gergely & Hunyadi sp. n. Figures 6, 8 F–K

Type material.

China, Guangxi (广西), Chongzuo Shi (崇左市), Longzhou Xian (龙州县), cliffs N of Lenglei (楞垒), N 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 99444 (holotype), HNHM 99445 (figured paratype), HA/2 paratypes.

Diagnosis.

Shell conical, with tumid body whorl and deep umbilicus; aperture with sinulus vertically oriented; tubus detached; aperture with one parietal lamella, one columellar and two palatal teeth; parietal lamella long and nearly straight.

Description.

Shell minute, whitish/light grey, conical with enlarged body whorl; protoconch consists of 1.5 or slightly less whorls, finely granulated, with at least six fine spiral striations; teleoconch reticulated and regularly spirally striated with strong, irregular radial lines; the 5.5 or slightly less whorls are separated by a deep suture; whorls sloping and rounded; aperture oblique to shell axis; base of shell broadly umbilicate due to lateral expansion of last whorl; aperture detached from the penultimate whorl; aperture with sinulus vertically oriented (from apertural view); peristome expanded, not reflected, with relatively sharp edge; four apertural barriers; only the angulo-parietal lamella reaches the peristome; angulo-parietal lamella very long and high, not interrupted; it is lowest near the peristome; its posterior (inner) end is not visible in frontal view; its anterior end (closest to the peristome) is bent toward the upper palatal plica, and its posterior end is bent toward the lower palatal plica; columellar and upper palatal folds elevated but short; the posterior end of the upper palatal fold curls toward the lower palatal fold; the lower palatal fold is also well-developed, and shorter than the others.

Measurements

(in mm): SH = 1.33-1.35, SW = 1.34-1.35, AH = 0.45-0.51, AW = 0.44-0.5 (n = 2). See also Tables 7 and 8.

Differential diagnosis.

See under Hypselostoma socialis sp. n.

Etymology.

The name lacrima (Latin: tear) refers to the shape of the aperture.

Type locality.

China, Guangxi (广西), Chongzuo Shi (崇左市), Longzhou Xian (龙州县), cliffs N of Lenglei (楞垒), N 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.

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 subdivision of Hypselostomatidae is strongly based on the morphology of the apertural barriers ( “teeth”). The main characters used for delimiting some of the major genera include the formation of the two teeth on the parietal region of the aperture, namely the parietal tooth (lamella) or parietalis and the angular tooth (lamella) or angularis. Gyliotrachela , Paraboysidia and Acinolaemus are said to possess separate parietal and angular lamellae. The former two have a more prominent parietal lamella rather than angular lamella, but in Acinolaemus , the angular is the dominant tooth. The angular lamella is entirely missing in the genus Anauchen . In the genera Hypselostoma and Boysidia these two lamellae are fused ( Pilsbry 1917, Thompson and Upatham 1997, Panha and Burch 2005). Sometimes it is challenging to ascertain whether we are dealing with a single lamella (homologous with the parietal lamella) having a bifid anterior end or two lamellae (parietal and angular), which are concrescent. Moreover, the genera Hypselostoma and Gyliotrachela did not form monophyletic units in the molecular phylogeny presented by Tongkerd et al. (2004), suggesting that the key characters used in classic taxonomy have developed phenotypically plastic forms. In this case of the two new species ( Hypselostoma lacrima sp. n. and Hypselostoma socialis sp. n.), we interpret the lamella on the parietal apertural wall as a congruent angulo-parietal lamella. Hence, both species are placed in Hypselostoma .