Chersaecia nagaensis nagaensis (Godwin-Austen, 1875)

Páll-Gergely, Barna, 2018, Systematic revision of the Plectopylinae (Gastropoda, Pulmonata, Plectopylidae), European Journal of Taxonomy 455, pp. 1-114 : 46-49

publication ID	https://doi.org/10.5852/ejt.2018.455
publication LSID	lsid:zoobank.org:pub:C445E95B-446A-4601-AAA3-C1CCBAB627F9
DOI	https://doi.org/10.5281/zenodo.3818752
persistent identifier	https://treatment.plazi.org/id/03CC87A0-6C01-8A17-FE3E-F9E643EDFE4E
treatment provided by	Valdenar (2020-05-08 18:45:36, last updated 2025-02-20 12:52:31)
scientific name	Chersaecia nagaensis nagaensis (Godwin-Austen, 1875)
status

Treatment

Chersaecia nagaensis nagaensis (Godwin-Austen, 1875) View in CoL

Figs 21 View Fig G–I, 22A

Helix (Plectopylis) nágáensis Godwin-Austen, 1875b: 609–610 , 612, pl. 73, fig. 4 [“Prowi, head of the Lauier river, Nágá hills, 5000 feet ”] (partim).

Helix (Plectopylis) nagaensis – Nevill 1878: 72. — Tryon 1887: 161, pl. 35, figs 78–79.

Plectopylis nagaensis View in CoL – Gude 1897a: 206–207, fig. 33a–d.

Plectopylis (Chersaecia) nagaensis View in CoL – Gude 1899d: 148; 1899e: 175; 1914b: 96–97, fig. 42a–d. Chersaecia nagaensis View in CoL – Páll-Gergely et al. 2015c: 10.

Diagnosis

Main plica present.

Material examined

Types INDIA: 10 shells, syntypes of P. nagaensis , Naga Hills, Prowi, head of Lanier Valley, coll. GodwinAusten ( NHMUK 1903.7.1.753).

Additional material

INDIA: 1 shell, Japvo Pk, Naga Hills ( NHMUK 1903.7.1.3493); 2 adult shells (+ 2 juv. of questionable identity), Manipur Hills, Ogle leg. ( NHMUK 1903.07.01.777); 1 shell, Naga Hills, Ogle leg., coll. Godwin-Austen ( NHMUK); 9 shells, Prowi, NE Manipur, coll. Godwin-Austen ( NHMUK); 1 shell, Naga Hills, Hungerford leg. ( NHMUK 1891.3.17.352); 2 shells, coll. Godwin-Austen ( NHMUK 1909.3.26.74); 2 shells, Naga Hills ( NHMUK).

Description

SHELL. Sinistral, usually with dense brownish periostracum; two shells lacking periostracum had yellowish grey colour and densely alternating reddish and yellowish stripes on the dorsal surface; below periostracum shell surface very finely reticulated as a result of fine, dense radial ribs and nearly equally strong spiral striation; spire elevated, dorsal side domed/depressed conical; protoconch consists of 2.5–2.75 whorls, very finely granular, only last ca one whorl with rough irregular, radial sculpture; whorls 6.25–6.5; teleoconch whorls separated by a shallow suture; aperture rounded; peristome whitish, expanded and reflected; parietal callus slightly S-shaped, approximately as strongly developed as peristome; apertural fold strong, connected to parietal callus; umbilicus relatively narrow and deep, funnel-shaped.

Four opened shells were examined. Parietal side with a single lamella; both ends of lamella slightly elongated posteriorly; lamella with a very slight elongation anteriorly in position of intermediate plica; an opened shell (“ India ”, NHMUK 1874.9.26.3) with a short intermediate plica free from lamella; main plica free from lamella, reaching apertural fold; lower plica short, situated under the lamella, slightly extends beyond lamella in both anterior and posterior directions. Palatal wall with six plicae; first curved and situated near suture; second considerably elongated anteriorly, with an additional, small denticle at its posterior end; above this denticle there is another tiny denticle; third and fourth plicae shorter than second, slightly depressed Z-shaped; fifth plica shorter than fourth, divided in the middle (only visible from inside); sixth plica short, situated near suture, and positioned under the line of posterior denticles/ posterior parts of divided plicae.

MEASUREMENTS (in mm). D = 11.6–12.2, H = 6.3–6.8 (n = 3, type series of nagaensis ).

Differential diagnosis

The main plica is long, and connected to the apertural fold (absent in Chersaecia nagaensis muspratti ).

Distribution

All known localities are within the Naga Hills and Manipur, northeastern India.

Remarks

The ‘dwarfed variety’ of Plectopylis nagaensis , which was mentioned in the original description of the species, is described here under the name Chersaecia shiroiensis subnagaensis subsp. nov.

References

Blanford W. T. 1865. Contributions to Indian Malacology, No. V. Descriptions of new land shells from Arakan, Pegu, and Ava; with notes on the distribution of described species. Journal of the Asiatic Society of Bengal 34 (2): 66 - 105. Available from https: // biodiversitylibrary. org / page / 37191013 [accessed 30 Jul. 2018].

Godwin-Austen H. H. 1875 b. Descriptions of five new Species of Helicidae of the Subgenus Plectopylis, with remarks on all the other known forms. Proceedings of the Zoological Society of London 1874: 608 - 613. Available from https: // biodiversitylibrary. org / page / 28502797 [accessed 30 Jul. 2018].

Gude G. K. 1897 a. Armature of Helicoid landshells. Science Gossip 3 (32): 204 - 207. Available from https: // biodiversitylibrary. org / page / 33878824 [accessed 30 Jul. 2018].

Gude G. K. 1899 d. Armature of Helicoid landshells and new sections of Plectopylis. Science Gossip 6 (65): 147 - 149. Available from https: // biodiversitylibrary. org / page / 34012981 [accessed 30 Jul. 2018].

Gude G. K. 1899 e. Armature of Helicoid landshells. Science Gossip 6 (66): 174 - 177. Available from https: // biodiversitylibrary. org / page / 34123273 [accessed 30 Jul. 2018].

Gude G. K. 1914 b. The Fauna of British India including Ceylon and Burma. Mollusca. ‾ II. (Trochomorphidae- - Janellidae). Taylor & Francis, London. Available from https: // biodiversitylibrary. org / page / 12910698 [accessed 30 Jul. 2018].

Nevill G. 1878. Hand list of Mollusca in the Indian Museum, Calcutta. Part I. Gastropoda. Pulmonata and Prosobranchia-Neurobranchia. Order of the Trustees, Calcutta. Available from https: // biodiversitylibrary. org / page / 19872326 [accessed 30 Jul. 2018].

Pall-Gergely B., Budha P. B., Naggs F., Backeljau T. & Asami T. 2015 c. Review of the genus Endothyrella Zilch, 1960 with description of five new species (Gastropoda, Pulmonata, Plectopylidae). ZooKeys 529: 1 - 70. https: // doi. org / 10.3897 / zookeys. 529.6139

Solem A. 1966. Some non-marine mollusks from Thailand, with notes on classification of the Helicarionidae. Spolia Zoologica Musei Hauniensis 24: 1 - 110.

Tryon G. W. 1887. Manual of Conchology; Structural and Systematic. With Illustrations of the Species. Ser. 2, vol. 3. Helicidae, Volume I. Published by the Author, Philadelphia. Available from https: // biodiversitylibrary. org / page / 1287540 [accessed 30 Jul. 2018].

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.