Angustopila coprologos Páll-Gergely, Jochum & Hunyadi, 2022

Páll-Gergely, Barna, Jochum, Adrienne, J. Vermeulen, Jaap, Anker, Katja, Hunyadi, András, Örstan, Aydin, Szabó, Ábel, Dányi, László & Schilthuizen, Menno, 2022, The world’s tiniest land snails from Laos and Vietnam (Gastropoda, Pulmonata, Hypselostomatidae), Contributions to Zoology 91, pp. 62-78 : 66-69

Angustopila coprologos Páll-Gergely, Jochum & Hunyadi n. sp.

urn:lsid:zoobank.org:act:D4A1491F-EA4B-4453-8FD9-7317500CEC28

Type material: Laos, Bolikhamsai Province, 15 km southeast + 4.5 km northeast (on a side road) towards centre of Lak Sao, Phu Phako , limestone gorge, 510 m a.s.l., 18°06.546’N, 105°03.778’E, (locality code: 2019/110), leg. A. Hunyadi, 2 October 2019, holotype ( HNHM 104885 ) ; CUMZ 7435 / 2 paratypes ; SMF 365053 / 2 paratypes ; VNMN / 2 paratypes ; ZRC. MOL.23217/ 2 paratypes , HA/ 697 paratypes .

Diagnosis: A strongly depressed-globular Angustopila species with a wide umbilicus, strong spiral sculpture consisting of a series of coarse elevations (flat-topped beads) in a chain-like pattern and four well-developed teeth (1 parietal, 2 palatal, 1 basal).

Description: Shell tiny, whitish, strongly depressed-globular, dorsal part domeshaped, body whorl widest in standard apertural view; protoconch with slightly less than 1.5 whorls and a minute and very uneven pattern of polygonal, rather sharpcrested ridges locally forming minute, conical peaks where ridges split (the structure also reminiscent of cross-sectional trabecular bone); this surface structure forms raised spiral striae on last half of protoconch whorl, and gradually becomes stronger towards first teleoconch whorl; teleoconch bears similar basal sculpture as that of protoconch, strongly ornamented by a pattern of elevated, equidistantly-arranged rows of elegantly linked flat-topped beads; some fine, irregular radial sculpture also visible, but none especially conspicuous due to prominent bead-like striations; whorls 3.25–3.5, separated by deep suture; whorls slightly shouldered; aperture oblique to shell axis in lateral view; umbilicus wide, ca. one third of shell width, in living specimens containing several mud granules; aperture narrow, semilunar, sinulus relatively wide, rather strongly separated due to strong parietal tooth; peristome expanded, not reflected; parietal callus strongly protruding, remarkably visible in lateral perspective as projecting beyond peristome and nearly in line with shell periphery, detached from penultimate whorl; parietal tooth strongly developed, long, curved, pointing towards upper palatal tooth; palatal wall with an upper, smaller tooth situated at peristome edge, and a slightly larger, lower tooth situated somewhat deeper, both blunt; columellar/basal, tooth blunt with wide base, positioned on lower part of columellar area, located at similar distance from peristome edge as lower palatal tooth.

Soft anatomy unknown.

Measurements (in mm): SW = 0.66–0.76; SH = 0.49–0.58 (n = 19).

Differential diagnosis: Angustopila coprologos n. sp. can be easily distinguished from all other Angustopila species by its depressed shell, the four apertural denticles and the pronounced sculpture.

Etymology: The specific epithet coprologos (Ancient Greek for dung gatherer) refers to the mud granules (here assumed to be faeces) placed on this species’ shell. Used as a noun in apposition.

Distribution: This species is known only from the type locality in Bolikhamsay Province, Laos: ca. 13 km southeast (in a straight line) from the town Lak Sao (see also supplementary figs S1–S 2 ).

Habitat: Since no living individuals were found (only shells of freshly dead specimens), no observations about the specific habitat of Angustopila coprologos n. sp. could be made. The living snails presumably live deep in limestone crevices close to (or on) root systems. The summer of 2019 was very wet and rainy with extensive flooding throughout the flood plains of the Mekong River. This might have played a role in the vast accumulation of empty shells at the base of rock formations (collection in October 2019).

Figures

FIGURE 1 Angustopila coprologos n. sp.(holotype).

FIGURE 2 Granules on the shell surface of A.coprologos n. sp. shells.A–B shows a shell with brown ‘mud’, whereas C–D shows a shell with white (calcareous) granules.