Chersaecia leucochila (Gude, 1897) Páll-Gergely, Barna, 2018

Páll-Gergely, Barna, 2018, Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae), European Journal of Taxonomy 455, pp. 1-114 : 41-42

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.

Figures

Fig. 15. Parietal (A, C, E, G, I, K, L, N, P, R) and palatal (B, D, F, H, J, M, O, Q, S) plication of species of Chersaecia Gude, 1899. A–B. C. auffenbergi sp. nov. (UF 448572). C–D. C. feddeni (Blanford, 1865) comb. nov. (after Gude 1914b). E–F. C. feddeni (“Plectopylis ponsonbyi”, after Gude 1896b). G–H. C. goniobathmos (Ehrmann, 1922) comb. nov. (SMF 150100c). I–J. C. leiophis (Benson, 1860) (NHMUK 1902.02.02.145). K. C. leiophis (“pseudophis”, after Gude 1914b). L–M. C. leiophis (“kengtungensis”, after Gude 1914b). N–O. C. leiophis (UF 446988). P–Q. C. leiophis, holotype of Plectopylis degerbolae Solem, 1966 (ZMUC-GAS-485). R–S. C. leucochila (Gude, 1897) comb. nov. (NHMUK 1922.8.29.39). Arrows below the letters indicate the direction of the aperture. Not to scale.