Chuatienpupa megacanalis, Sang & Son, 2023

Sang, Do Duc & Son, Nguyen Thanh, 2023, A new genus and new species of Pupinidae (Gastropoda: Caenogastropoda) from Northern Vietnam, Ruthenica, Russian Malacological Journal 33 (1), pp. 19-26 : 21-23

Chuatienpupa megacanalis sp. nov.

( Figs 1, 2, 3 A–H , 5 A–D)

ZooBank registration: urn:lsid:zoobank.org:act:

Type material. Holotype VNMN-IZ 000.002.331 (shell height 9.1 mm, shell width 4.6 mm, Fig. 3A–E ), Vietnam, Hoa Binh province, Lac Thuy district, Phu Lao commune, forests over limestone and limestone hills around the Chua Tien pa- goda (20°33.25’N, 105°44.50’E), coll. D.S. Do, 04 February 2022 . Paratypes: VNMN-IZ 000.002.332 (2 shells), ZVNU. MOL 047 (3 shells), DDS (8 shells), same data as holotype .

Diagnosis. Shell pupoid shaped, rather solid and glossy. Peristome thickened, not expanded, inter- rupted by anterior and posterior canals. Posterior canal separated by palatal lip by lower palatal plica, and an additional plica (upper palatal plica) divides posterior canal into two. Columellar area strongly thickened and expanded, with lower part curving into hook-like plica. Anterior canal very wide, twisted funnel-shaped, and opened on basal side. Operculum outside bowl-shaped, and flat inside.

Description. Shell horny or yellowish, smooth, glossy and slightly transparent, covered by a glaze, pupoid shape with slightly pointed apex. Peristome and its surrounding area clearly distinguished from the other areas by its characteristic ivory colour or transparency. The increase of the whorls is rather regular, slow at the beginning, but suddenly increas- ing in the last whorls, but not bulging. Shell rather solid, composed of 5–5.5 whorls. Protoconch quite smooth and approximately of 1.5 whorls, although the boundary between the protoconch and the teleo- conch is not easily discernible. Suture superficial, margined. The upper whorls moderately bulging, last two whorls less bulging; last whorl occupies more than 2/3 of the total shell height. Aperture circular, slightly oblique and basal part protruding. Peristome complex, thickened, not expanded, and interrupted by two canals: one at parieto-angular corner (pos- terior canal), and one at basal area (anterior canal). Parietal callus strong, margin slightly elevated and with large parietal tooth. Palatal area quite thickened, the upper part less expanded than on the lower part; the upper part quite concave (observed from lateral view), with two large triangular-like plicae, which are directed toward the parietal plica. Basal area extends obliquely, largely occupied by anterior canal, a strong scythe-shaped plica (basal plica), which seems to bisect the anterior canal (more obvious from basal view). Columella strongly thickened and expanded, lower part curving into hook-like plica (columellar plica) that covers anterior canal. Posterior canal con- tinues vertically upward and forming wide groove divided into two cavities. Anterior canal twisted funnel-shaped, appearing as very wide groove that opens on basal side. Umbilicus closed.

Operculum quite solid, closed bowl-shaped, but hollow inside. Outer surface smooth, glossy, strongly convex, and covered by a glaze. Inner surface flat, slightly smooth, multispiral, with a low nipple on its central. Operculum uniform yellow-orange on outer surface ( Figs 1, 3F , 5 A–C).

Living specimens of Chuatienpupa megacanalis sp. nov. has a light grey to light brown body with a pinkish-brown to pale grey head and black tentacles ( Figs 5 A–C).

Variability. This species varies slightly in shell dimensions (smallest adult paratype shell is 8.4 mm x 4.3 mm) and in shell color (the most of the specimens are horny or yellowish).

Measurements (in mm). Shell height 8.4–9.3, shell width 4.3–5.0, aperture height 2.6–2.8, aperture width 2.1–2.4, and operculum diameter 1.9–2.0 (n = 14).

Distribution. This species is known from the type locality only.

Etymology. The species name is derived from its characteristic anterior canal, from the Latin words ‘ mega ’, meaning ‘large, great’ and ‘ canalis ’, mean- ing ‘canal’.

Ecology. This species collected from leaf litter at the foot of limestone rocks with dense disturbed veg- etation. Three other pupinid species, Pupina anceyi Bavay & Dautzenberg, 1899 , Pupina exclamationis Mabille, 1887 and Pupina verneaui Dautzenberg & Fischer, 1906 , were also recorded in the same habitat with the new species.

Remarks. In juvenile shells, as not yet covered by the thick glaze, the sculpture is absent or weak, the palatal plica has not appeared, and the basal area also has not expanded ( Fig. 5D).

Figures

FIG. 3. Chuatienpupa megacanalis sp. nov.A–E. Holotype VNMN-IZ 000.002.331.F–H. Paratypes ZVNU.MOL 047.Photos: Nguyen T.S. and Do D.S.