Chersaecia nagaensis muspratti (Gude, 1897), 2018

Páll-Gergely, Barna, 2018, Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae), European Journal of Taxonomy 455, pp. 1-114 : 49-50

Chersaecia nagaensis muspratti (Gude, 1897) comb. nov.

Figs 21 J–K, 22B

Plectopylis muspratti Gude, 1897f: 10 , fig. 45a–f [“ Naga Hills, Assam ”].

Plectopylis muspratti – Gude 1898h: 7–8, fig. 5a–f.

Plectopylis (Chersaecia) muspratti – Gude 1899d: 148; 1899e: 175; 1914b: 89–90, fig. 37a–f. Chersaecia muspratti – Páll-Gergely et al. 2015c: 10.

Diagnosis

A subspecies of Chersaecia nagaensis lacking the main plica.

Material examined

Syntypes INDIA: 2 shells, (diameter of photographed shell = 11.7 mm), Naga Hills, coll. Beddome ( NHMUK 1912.4.16.320).

Description

The description of the external shell is based on two syntypes deposited in the NHM. No additional material was found in that collection. Gude (1897f) described and figured the inner plicae based on the shells in Colonel Beddome’s collection. Therefore, the original description of the plicae is copied from Gude (1897f).

SHELL. Sinistral, with elevated spire, dorsal side conical; one of the shells corroded, but the other has a yellowish grey basic colour with reddish stripes, which results in a mosaic-like colouration on dorsal side; protoconch matt, almost smooth or with irregular growth lines; teleoconch with fine reticular structure; whorls 6–6.5 (n = 2), separated by rather deep suture; whorls rounded, not angled; peristome reflected and slightly thickened, parietal callus normally developed, S-shaped; apertural fold shorter than parietal callus, connected to it.

“Parietal wall with a short entering flexuous fold united to the ridge at the aperture, becoming attenuated inwardly, and at one-third of the circumference from the aperture, with a strong, crescent-shaped vertical plate, which is suddenly deflected posteriorly at the lower extremity; below this, on the anterior side, occurs a very short, horizontal fold. Palatal folds six, horizontal, short the first free, with a small denticle posteriorly; the second, third, fourth, and fifth connected with each other by a vertical ridge, which deflects below the fifth fold posteriorly and terminates in a small, oblique denticle; the sixth again free” ( Gude 1897f).

MEASUREMENTS (in mm). D = 11.7–12.9, H = 6.6–6.75 (syntypes, n = 2).

Differential diagnosis

Chersaecia nagaensis muspratti differs from the nominotypical subspecies by the absence of the main plica.

Distribution

The subspecies is known only from the type locality.

Remarks

The only notable difference between Plectopylis nagaensis muspratti and P. nagaensis nagaensis is the presence ( nagaensis ) or the absence ( muspratti ) of the main plica. Since there is no difference in the general shell or aperture shape, I assign P. muspratti as a subspecies of P. nagaensis .

Figures

Fig. 21. Parietal (A, C, E, G, I, J, L, N, P, R) and palatal (B, D, F, H, K, M, O, Q, S) plication of species of Chersaecia Gude, 1899. A–B. C. magna (Gude, 1897) comb. nov., holotype (NHMUK 1922.8.29.37). C–D. C. magna (“P. lissochlamys”, after Gude 1914b). E–F. C. mogokensis sp. nov., holotype (NHMUK 20140787). G–H. C. nagaensis (Godwin-Austen, 1875), syntypes (NHMUK 1903.7.1.753). I. C. nagaensis (NHMUK 1874.9.26.3). J–K. C. nagaensis muspratti (Gude, 1897) (after Gude 1914b). L–M. C. perarcta simplex (Solem, 1966) (after Solem 1966). N–O. C. perarcta perarcta (Blanford, 1865) (NHMUK 1906.2.2.275). P–Q. C. perarcta perarcta (UF 448575). R–S. C. perarcta perarcta, loc. “5.5 km west of Chiang Rai” (coll. PGB). Arrows below the letters indicate the direction of the aperture. Not to scale.