Angustopila psammion Pall-Gergely, Anker & Vermeulen 2022, n. sp.
Creators: name: Páll-Gergely, Barna
name: Jochum, Adrienne
name: J. Vermeulen, Jaap
name: Anker, Katja
name: Hunyadi, András
name: Örstan, Aydin
name: Szabó, Ábel
name: Dányi, László
name: Schilthuizen, Menno
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Stylommatophora
Gastrocoptidae
Angustopila
Angustopila psammion

description: Angustopila psammion Páll-Gergely, Anker & Vermeulen, n. sp.
urn:lsid:zoobank.org:act:EAD52AC1-985A-48E7-8AF9-4C2629C416BF
Type material: Vietnam, Quang Ninh Province, Ha Long Bay, Cap La Cave, 20°51.793’N, 107°13.541’E, soil deposit fallen through roof in pristine cave, vegetation outside cave tall and woody, leg. J.J. Vermeulen & K. Anker, 07 March 2018, holotype (HNHM 104886); CUMZ 7436 / 2 paratypes; SMF 365052 / 2 paratypes; VNMN / 2 paratypes; ZRC. MOL.23218/ 2 paratypes, jjV 17633/ 409 paratypes.
Diagnosis: An Angustopila species with a depressed-globular shell with dome-shaped spire, thick spiral striae, kidney-shaped aperture with single parietal denticle not reaching parietal callus.
Description: Shell tiny, off-white, depressed-globular form with domed spire; body whorl widest in standard apertural view; protoconch with 1.5 whorls and a minute and very uneven pattern of polygonal, rather sharp-crested ridges locally forming minute, conical peaks where ridges split (the structure also reminiscent of cross-sectional trabecular bone), no spiral striation discernible; teleoconch ornamented by some weak radial growth lines and much stronger, ropelike, equidistantly-arranged spiral striae (ca. 14–15 on body whorl from standard apertural view); the 3.25–3.5 whorls are separated by a deep suture; whorls slightly shouldered; aperture oblique to shell axis in lateral view; umbilicus relatively wide, less than one third of shell width; aperture kidney-shaped with strongly concave parietal side; sinulus wide, weakly separated due to weak parietal tooth; peristome expanded, not reflected; parietal callus strongly protruding, but in line with curvature of penultimate whorl and beyond aperture edge (profile) in lateral view (fig. 3C), detached from penultimate whorl; parietal tooth weak, low, short, rounded, does not reach peristome.
Soft anatomy unknown.
Measurements (in mm): SW = 0.6–0.68, SH = 0.46–0.57 (n = 24).
Differential diagnosis: Angustopila pallgergelyi Dumrongrojwattana, Chuenit & Wongkamhaeng, 2021 is similar in shell and aperture shape, but is larger, has a prominent palatal tooth (absent in Angustopila psammion n. sp.)and a stronger parietal tooth. Angustopila coprologos n. sp. is slightly larger, has a rough shell surface, and has an additional subcolumellar tooth and two palatal teeth.
Etymology: The specific epithet (ΨαμμϯΟν) means a grain of sand in Greek and is used as a noun in apposition.
Distribution: This new species is known only from the type locality, Cap La Cave, Ha Long Bay, Quang Ninh Province, Vietnam.
Habitat: Angustopila psammion n. sp. was found in large numbers in small sediment deposits along the walls of a dry cave (Cap La Cave), in complete darkness. We assume that the sediment had fallen in through crevices in the rock, because it contains a species-rich assemblage of bleached, opaque shells of surface-dwelling terrestrial gastropods. Shells of Angustopila psammion n. sp., however, look fresh and are probably autochthonous.
description: Published as part of 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), pp. 62-78 in Contributions to Zoology 91 on pages 69-71, DOI: 10.1163/18759866-BjA10025, http://zenodo.org/record/6147303