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Table 2 in New species of Georissa (Gastropoda: Hydrocenidae) and Acmella (Gastropoda: Assimineidae), with new records of Georissa from Northeast India
Authors/Creators
- 1. SM Sehgal Foundation Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Sriramapura, Jakkur PO, Bangalore 560064, India. & Manipal Academy of Higher Education (MAHE), Madhav Nagar, Manipal, Udupi 576104, India. & Department of Zoology, Kamrup College, Chamata, Nalbari, 781306, Assam, India.
- 2. SM Sehgal Foundation Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), Royal Enclave, Sriramapura, Jakkur PO, Bangalore 560064, India. & Manipal Academy of Higher Education (MAHE), Madhav Nagar, Manipal, Udupi 576104, India. & Yenepoya Research Centre, Yenepoya (Deemed to be University), University Road, Derlakatte, Mangalore 575018, India.
Description
Table 2 (continued on next page). Comparison of conchological characters of all species of Acmella W.T. Blanford, 1869 from India and Myanmar.
| Characters | A. bensoni sp. nov. | A. tersa W.H. Benson, 1853 | A. mellilla Godwin-Austen, 1895 | A. moreletiana G. Nevill, 1878 | A. roepstorffiana G. Nevill, 1878 | A. hyalina Theobald & Stoliczka, 1872 |
|---|---|---|---|---|---|---|
| Size (SH × SW) (in mm) | 1.22–1.37 × 1.03–1.09 | 2.14–2.38 × 1.45–1.66 | 1.75 ×1.25 | 2 × 1.33 | 1.5 × 1 | 1 × 0.7 |
| Shell shape | conical-oval, turbinate, shiny and somewhat transparent, and depressed | typical assimineid (conical to ovoid), somewhat semi-transparent | ovately turreted, somewhat semi-transparent | conical-turreted, hyaline/ glossy, transparent, polished, and shining | conico-turrited, shining, translucent, silky | ovately conical, hyaline |
| Color | white | brownish corneous | pale umber | white | – | dirty whitish |
| Umbilicus | open and wide | narrow, nearly closed | widely open | widely open | open | moderately perforated |
| Whorls | 4.25–4.5, convex | 4.5–5, convex | 5–5.5, sides flat | 5, highly convex, last whorl globular, convex below | 5, slightly convex whorls, gradate, last whorl subcylindrical, slightly compressed at periphery, convex beneath | 4.5, somewhat convex |
| Liration | indistinct, fine and densely spaced spiral and radial ribs or growth lines across shell surface, fine radial ribs clearly visible on neck of aperture | protoconch finely granulose, teleoconch with irregular, rather strong, somewhat wavy ribs, some of which may converge | sculpture oblique, fine, close costulation, radially ribbed across shell, very densed and overlapped at aperture neck | sculptured round umbilicus in very characteristic manner, with regular distinct plications, beneath suture, faint striation is discernible, with lens | entirely distinct, somewhat strongly, closely, evenly or regularly striated; striae thread-like, oblique, more prominent toward base, especially around umbilical region | smooth |
| Spire | acuminate | acuminate | depressedly conic | depressedly conical | acuminate | blunt |
| Apex | conical | conical | very blunt | blunt | blunt and conical | conical |
| Suture | moderate to well-impressed with slightly extended shoulder | well-impressed | impressed | well-impressed | well-impressed | simple and deep suture |
| Aperture | ovate-lunate, oblique or sub-vertical | prosocline, only slightly oblique to shell axis from lateral view, elongate ovoid with pointed parieto-palatal angle | oval, suboblique | perfectly rounded, margins closely approximated but not continuous | very small, subcircular, with margins almost but not continuous, columellar one being abruptly bent back over umbilicus and then beautifully and boldy rounded | regularly ovate, above (or posteriorly) somewhat angled, not oblique |
| Peristome | simple, somewhat thick and continuous, parietal lip straight, sometimes indistinct, merged with body-whorl, parieto-palatal juncture distinct and sharply angulated, palatal, basal and columellar lips or edges roundish | sharp, not expanded | double, with strong callus on body whorl | slightly thickened, columellar margin gradually rounded, not covering the umbilicus. | thickened, not continuous, externally slightly expanded; columellar margin strongly arched, more or less covering the umbilicus | thin, almost continuous |
| Operculum | unknown | horny, extremely thin, paucispiral | unknown | unknown | unknown | absent? |
| Habitat | both dry and wet walls of cave, approximately 4–12 m from cave entrance | moss in forest | tropical rainforest | tropical rainforest | midddy coastal area | on limestone hills |
| Distribution | Krem Puri, Meghalaya, India; Arwah Cave, Meghalaya, India | Mawsmai Cave, Musmai (= Mawsmai) near Cherrapunji (= Cherrapunjee), Meghalaya, India | South Andaman, India | Batti Malve, Nicobar Islands, India | Katchall, Nicobar Islands, India | South of Moulmein, Myanmar |
Notes
Published as part of Das, Nipu Kumar & Aravind, Neelavar Ananthram, 2026, New species of Georissa (Gastropoda: Hydrocenidae) and Acmella (Gastropoda: Assimineidae), with new records of Georissa from Northeast India, pp. 18-19 in European Journal of Taxonomy 1060 on page 18, DOI: 10.5852/ejt.2026.1060.3284, http://zenodo.org/record/20411389
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Additional details
Identifiers
References
- Blanford W. T. 1869. Note on Hydrocena tersa, Benson, and H. milium, Bens. Annals and Magazine of Natural History, Series 4 3: 177-179. Available from https://www.biodiversitylibrary.org/page/50398876 [accessed 4 Apr. 2026].
- Benson W. H. 1853. Additional character of the shell of the cyclostomatous genus Alycaeus of Gray, with descriptions of its animal inhabitant, - of a fourth species, - and of other new Indian Cyclostomata; also, remarks on an unrecorded character in Diplommatina. Annals and Magazine of Natural History, Series 2 11: 283-287. Available from https://www.biodiversitylibrary.org/page/13786021 [accessed 4 Apr. 2026].
- Nevill G. 1878. Hand List of Mollusca in the Indian Museum, Calcutta. Part I. Gastropoda. Pulmonata and Prosobranchia-Neurobranchia. Office of the Superintendent of Government Printing, Calcutta. Available from https://www.biodiversitylibrary.org/page/19872326 [accessed 4 Apr. 2026].
- Theobald W. & Stoliczka F. 1872. Notes on Barmese and Arakanese land shells, with descriptions of a few species. Journal of the Asiatic Society of Bengal 41 (2): 329-334. Available from https://www.biodiversitylibrary.org/page/37138045 [accessed 4 Apr. 2026].