Chersaecia leucochila (Gude, 1897) comb. nov.

Figs 15 R–S, 19C

Plectopylis leucochilus Gude, 1898a: 231, fig. 66a–e [“ Burma ”].

Plectopylis leucochila – Gude 1898b: 264 (erratum).

Plectopylis leucochilus – Gude 1898h: 13–14, fig. 9a–e.

Plectopylis (Plectopylis) leucochila – Gude 1899d: 148; 1899e: 175; 1914b: 126–127, fig. 62a–e.

Diagnosis

Shell medium-sized, domed, parietal wall with two lamellae and long lower and main plicae, palatal wall with typical Plectopylis -like plicae.

Material examined

Holotype MYANMAR: 1 shell, holotype (D = 16 mm), Burma (NHMUK 1922.8.29.39).

Additional material

INDIA: 1 shell (from type sample of Chersaecia austeni), Diyung valley, Singpho Hills, Assam, Ogle leg. (NHMUK 1903.06.01.1014.1).

In the type sample of Chersaecia austeni (NHMUK 1903.06.01.1014), a sinistral shell was found which is identical to the holotype of C. leucochila . A lectotype of the sample of C. austeni was therefore selected (see under that species).

Description

SHELL. Sinistral, medium-sized, light grey; spire slightly elevated; protoconch consists of 2.75 whorls, extremely finely granular, with rough, rather regular radial ribs; whorls 7.5, separated by shallow (protoconch) and deep (teleoconch) suture; teleoconch weathered, but the rough, rather irregular radial ribs, the much weaker spiral striation and the remains of periostracal folds near the suture still visible; aperture rounded; peristome expanded and slightly reflected; parietal callus slightly S-shaped, rather blunt; apertural fold free from parietal callus; umbilicus funnel-shaped, narrow compared to other members of the genus.

The holotype had been opened by Gude. Parietal wall with two vertical lamellae; posterior lamella thin, oblique to suture, with short elongations in both directions at its lower end; anterior lamella shorter, thicker, both ends elongated anteriorly; upper elongation continuous with main plica; main plica connected to apertural fold; lower elongation represents short intermediate plica; posterior elongations of anterior lamella not visible through opaque shell. Palatal plicae six; first slender, situated close to the suture; second strongly elongated anteriorly; third shorter, posterior end curved downwards; fourth and fifth form a slightly S-shaped, vertical plate; sixth curved, situated close to lower suture.

MEASUREMENTS (in mm). D = 16, H = 6.7 (holotype of leucochila).

Differential diagnosis

See under C. feddeni and C. magna .

Distribution

This species is known from Burma (Myanmar) only.A single shell found in the type sample of C. austeni from Assam, India, was probably misplaced.