New species of Georissa (Gastropoda: Hydrocenidae) and Acmella (Gastropoda: Assimineidae), with new records of Georissa from Northeast India
Abstract
The present study describes one new species each of Georissa and Acmella from Northeast India. Georissa meghalayaensis sp. nov. and Acmella bensoni sp. nov. are described from Krem Puri, Meghalaya. In addition, Georissa sp. was newly recorded from a soil-leaf litter sample collected at the Sadu Chiru waterfall area in Manipur, and Georissa sarrita was newly recorded from Tuipui in Mizoram. All species were identified based on morphological features, with shell sculpture and suture being the primary distinguishing characters. Notably, all the species from Meghalaya were found inside caves, except for Georissa meghalayaensis (Krem Puri), which was found at the edge of the cave entrance on a wet, moss-covered rocky wall. Further studies are required to confirm the true cavernicolous nature of these microsnails.
References
Aravind N.A. & Páll-Gergely B. 2023. Two extraordinary alycaeid species from Northeastern India (Gastropoda: Caenogastropoda: Cyclophoroidea). Acta Zoologica Academiae Scientiarum Hungaricae 69 (4): 353–363. https://doi.org/10.17109/AZH.69.4.353.2023
Auffenberg K. & Páll-Gergely B. 2020. Reassignment of three species and one subspecies of Philippine land snails to the genus Acmella Blanford, 1869 (Gastropoda: Assimineidae). Tropical Natural History 20: 223–227. https://doi.org/10.58837/tnh.20.3.243510
Benson W.H. 1851. Geographical notices, and characters of fourteen new species of Cyclostoma, from the East Indies. Annals and Magazine of Natural History, Series 2 8 (45): 184-195. Available from https://www.biodiversitylibrary.org/page/22250400 [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].
Benson W.H. 1856. Characters of seventeen new forms of the Cyclostomacea from the British Provinces of Burmah, collected by W. Theobald, jun., Esq. Annals and Magazine of Natural History, Series 2 17 (99): 225–228 [1 March]; 17 (100): 229–233 [1 April]. Available from https://biodiversitylibrary.org/page/22069820 [accessed 4 Apr. 2026].
Benson W.H. 1860. Characters of new land-shells from Burmah and the Andamans. Annals and Magazine of Natural History, Series 3 6 (33): 190–195. Available from https://www.biodiversitylibrary.org/page/2267380 [accessed 4 Apr. 2026].
Bernasconi R. 1995. Two new cave prosobranch snails from Papua New Guinea: Selmistomia beroni n. gen. n. sp. (Caenogastropoda: Hydrobiidae) and Georissa papuana n. sp. (Archaeogastropoda: Hydrocenidae). (Zoological results of the British Speleological Expedition to Papua New Guinea 1975). Revue suisse de Zoologie 102 (2): 373–376. https://doi.org/10.5962/bhl.part.80470
Berry A.G. 1961. The habitats of some minute cyclophorids, hydrocenids and vertiginids on a Malayan limestone hill. Bulletin of the Singapore National Museum 30: 101–105.
Berry A.G. 1965. Reproduction and breeding fluctuations in Hydrocena monterosatiana, a Malayan limestone archaeogastropod. Proceedings of the Zoological Society of London 144: 219–227. https://doi.org/10.1111/j.1469-7998.1965.tb05174.x
Blanford W.T. 1864. On the classification of the Cyclostomacea of eastern Asia. Annals and Magazine of Natural History, Series 3 13 (78): 441–465. Available from https://www.biodiversitylibrary.org/page/22217703 [accessed 4 Apr. 2026].
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].
Boettger O. 1891. Ad. Strubell’s Konchylien aus Java II und von den Molukken. Bericht über die Senckenbergische Naturforschende Gesellschaft in Frankfurt am Main 1891: 241–318. Available from https://www.biodiversitylibrary.org/page/47621273 [accessed 4 Apr. 2026].
Chen D.N. & Zhang G.Q. 1998. Description on new species and zoogeographical analysis of the land mollusks from Xishuangbanna and neighboring area, Yunnan Province (Gastropoda: Prosobranchia: Archaeogastropda: Mesogastropoda). Acta Zootaxonomica Sinica 4: 346–359.
Chen Z.Y. & Páll-Gergely B. 2023. A new species of Anaglyphula Rensch, 1932 from an island off the coast of West Indonesia, with redescription of the type species (Gastropoda: Caenogastropoda: Assimineidae). Raffles Bulletin of Zoology 71: 597–605. https://doi.org/10.26107/RBZ-2023-0046
Das N.K. & Aravind N.A. 2021. A new species from the genus Georissa Blanford, 1864 (Gastropoda, Neritimorpha, Hydrocenidae) from a limestone cave of Meghalaya, Northeast India. Journal of Conchology 44 (2): 93 –101.
Das N.K. & Aravind N.A. 2024. New distribution records of three terrestrial snails of the Genus Bouchetcamaena Thach, 2018 (Gastropoda, Camaenidae) from Northeast India. Records of the Zoological Survey of India 124 (iS2): 115–120. https://doi.org/10.26515/rzsi/v124/i1s/2024/172721
Das N.K., Páll-Gergely B., Naggs F., Preece R.C., White T.S. & Aravind N.A. 2021. Redescription of Acmella tersa (Benson, 1853), the type species of Acmella W.T Blanford, 1869 (Gastropoda: Assimineidae) from Meghalaya, Northeast India. Molluscan Research 41 (4): 324–331. https://doi.org/10.1080/13235818.2021.1991255
Dey A., Barua S. & Mitra S.C. 2003. Mollusca. In: Fauna of Sikkim, State Fauna Series 9, Part 5: 129–144. Zoological Survey of India, Kolkata.
Dumrongrojwattana P., Kamtuptim C. & Wongkamhaeng K. 2020. A review of Diplommatina species in eastern Thailand with the descriptions of five new species. Biodiversity Data Journal 8: e57689. https://doi.org/10.3897/bdj.8.e57689
Foon J.K., Clements G.R. & Liew T.S. 2007. Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia. ZooKeys 682: 1–94. https://doi.org/10.3897/zookeys.682.12999
Fukuda H. & Mitoki T. 1995. A revision of the family Assimineidae (Mollusca: Gastropoda: Neotaenioglossa) stored in the Yamaguchi Museum. Part 1: subfamily Omphalotropidinae. Bulletin of the Yamaguchi Museum 21: 1–20
Godwin-Austen H.H. 1889. On a collection of land-shells made in Borneo by Mr. A. Everett with supposed new species. Part I. Cyclostomacae. Proceedings of the Zoological Society of London 57 (3): 332–335. Available from https://biodiversitylibrary.org/page/28698963 [accessed 4 Apr. 2026].
Godwin-Austen H.H. 1895. List and distribution of the land-Mollusca of the Andaman and Nicobar Islands, with descriptions of some supposed new species. Proceedings of the Zoological Society of London 63 (30): 438–457. Available from https://www.biodiversitylibrary.org/item/97158#page/536/mode/1up [accessed 4 Apr. 2026].
Godwin-Austen H.H. & Nevill G. 1879. Descriptions of shells from Perak and the Nicobar Islands. Proceedings of the Zoological Society of London 47 (4): 734–740. Available from https://biodiversitylibrary.org/page/28521906 [accessed 4 Apr. 2026].
Gredler V.M. 1889. Zur Conchylien-Fauna von China. XIV. Stück. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 21: 155–163. Available from https://www.biodiversitylibrary.org/page/15599998 [accessed 4 Apr. 2026].
Grego J. 2018. First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae). Subterranean Biology 25: 9–34. https://doi.org/10.3897/subtbiol.25.23563
Harries D.B., Ware F.J., Fischer C.W., Biswas J. & Kharpran-Daly B.D. 2008. A review of the biospeleology of Meghalaya, India. Journal of Cave and Karst Studies 70 (3): 163–176. Available from https://caves.org/wp-content/uploads/Publications/JCKS/v70/cave-70-03-163.pdf [accessed 4 Apr. 2026].
Harries D.B., Kharkongor I.J. & Saikia U. 2020. The biota of Siju Cave, Meghalaya, India: A comparison of biological records from 1922 and from 2019. Cave and Karst Science 47 (3): 119–130.
Inkhavilay K., Sutcharit C., Bantaowong U., Chanabun R., Siriwut W., Srisonchai R., Pholyotha A., Jirapatrasilp P. & Panha S. 2019. Annotated checklist of the terrestrial molluscs from Laos (Mollusca, Gastropoda). ZooKeys 834: 1–166. https://doi.org/10.3897/zookeys.834.28800
Jochum A., Slapnik R., Kampschulte M., Martels G., Heneka M. & Páll-Gergely B. 2014. A review of the microgastropod genus Systenostoma Bavay & Dautzenberg, 1908 and a new subterranean species from China (Gastropoda, Pulmonata, Hypselostomatidae). ZooKeys 410: 23–40. https://doi.org/10.3897/zookeys.410.7488
Khalik M.Z., Hendriks K., Vermeulen J.J. & Schilthuizen M. 2018. A molecular and conchological dissection of the “scaly” Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae). ZooKeys 773: 1–55. https://doi.org/10.3897/zookeys.773.24878
Khalik M.Z., Hendriks K.P., Vermeulen J.J. & Schilthuizen M. 2019. Conchological and molecular analysis of the “non-scaly” Bornean Georissa with descriptions of three new species (Gastropoda, Neritimorpha, Hydrocenidae). ZooKeys 840: 35–86. https://doi.org/10.3897/zookeys.840.33326
Klongklaew K., Poeaim S. & Dumrongrojwattana P. 2024. Four new species of Georissa W. Blanford, 1864 (Gastropoda, Hydrocenidae) from Thailand. Zoosystematics and Evolution 100 (4): 1347–1360. https://doi.org/10.3897/zse.100.128717
Maassen W.J.M. 2000. Notes on terrestrial molluscs of Sumatra, Indonesia, with descriptions of ten new species (Gastropoda, Prosobranchia & Pulmonata). Basteria 64: 137–150. Available from http://natuurtijdschriften.nl/download?type=document;docid=597195 [accessed 4 Apr. 2026].
Mabille J. 1887. Molluscorum Tonkinorum diagnoses. Meulan.
Marzuki M.E. bin, Liew T.S. & Mohd-Azlan J. 2021. Land snails and slugs of Bau limestone hills, Sarawak (Malaysia, Borneo), with the descriptions of 13 new species. ZooKeys 1035: 1–113. https://doi.org/10.3897/zookeys.1035.60843
Möllendorff O.F. von 1885. Materialien zur Fauna von China. Jahrbücher der Deutschen Malakozoologischen Gesellschaft 12: 349–398. Available from https://www.biodiversitylibrary.org/page/16361886 [accessed 4 Apr. 2026].
Möllendorff O. F. von. 1894. On a collection of land-shells from the Samui Islands, Gulf of Siam. Proceedings of the Zoological Society of London 1894: 146–156. Available from https://biodiversitylibrary.org/page/35990426 [accessed 4 Apr. 2026].
Möllendorff O.F. von. 1900. Zur Binnenmollusken-Fauna Annams III. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 32 (9–10): 129–139. Available from https://www.biodiversitylibrary.org/page/15598474 [accessed 4 Apr. 2026].
Mookherjee H.P., Thakur D.K., Mitra S.C. & Barua S. 2000. Mollusca. In: State Fauna Series 7, Fauna of Tripura-Part 4: 323–355. Zoological Survey of India, Kolkata.
MolluscaBase 2026. MolluscaBase. Available from https://www.molluscabase.org/ [accessed 25 Mar. 2026]. https://doi.org/10.14284/448
Myers N., Mittermeier R.A., Mittermeier C.G., Da Fonseca G.A. & Kent J. 2000. Biodiversity hotspots for conservation priorities. Nature 403 (6772): 853–858. https://doi.org/10.1038/35002501
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].
Páll-Gergely B. 2020. A new genus of Diplommatinidae from the Andaman Islands (Gastropoda: Caenogastropoda: Cyclophoroidea). Molluscan Research 40 (3): 247–250. https://doi.org/10.1080/13235818.2020.1786924
Páll-Gergely B., Fehér Z., Hunyadi A. & Asami T. 2015a. Revision of the genus Pseudopomatias and its relatives (Gastropoda: Cyclophoroidea: Pupinidae). Zootaxa 3937 (1): 1–49. https://doi.org/10.11646/zootaxa.3937.1.1
Páll-Gergely B., Budha P.B., Naggs F., Backeljau T. & Asami T. 2015b. 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
Páll-Gergely B., Ablett J.D., Szabó M. & Neubert E. 2022. Revision of the “Chloritis delibrata (Benson, 1836)” group (Gastropoda, Stylommatophora, Camaenidae). ZooKeys 1086: 1–31. https://doi.org/10.3897/zookeys.1086.77180
Páll-Gergely B., Hunyadi A., Vermeulen J.J., Grego J., Sutcharit C., Reischütz A., Dumrongrojwattana P., Botta-Dukát Z., Örstan A., Fekete J. & Jochum A. 2023. Five times over: 42 new Angustopila species highlight Southeast Asia’s rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae). ZooKeys 1147: 1–177. https://doi.org/10.3897/zookeys.1147.93824
Páll-Gergely B., Gojšina V. & Aravind N.A. 2025. A review of Chamalycaeus, Cycloryx and Dicharax species of the Himalaya and Myanmar and seven new species of Alycaeinae from the Blue Mountain, Mizoram, India (Gastropoda, Caenogastropoda, Cyclophoridae). European Journal of Taxonomy 1029: 1–158. https://doi.org/10.5852/ejt.2025.1029.3131
Pilsbry H.A. & Hirase Y. 1908. New land shells of the Chinese Empire-I. Proceedings of the Academy of Natural Sciences of Philadelphia 60: 37–43. Available from https://www.biodiversitylibrary.org/page/24596968 [accessed 04 Apr. 2026].
Preece R.C., White T.S., Raheem D.C., Ketchum H., Ablett J., Taylor H., Webb K. & Naggs F. 2022. William Benson and the golden age of malacology in British India: Biography, illustrated catalogue and evaluation of his molluscan types. Tropical Natural History 6: 1–434. https://doi.org/10.58837/tnh.22.6.257073
Sajan S., Tripathy B., Chandra K. & Sivakumar K. 2019. Rediscovery and re-description of Rhaphaulus assamicus Godwin-Austen, 1886, an endemic pupinid land snail from India (Gastropoda: Pupinidae). Journal of Natural History 53 (41–42): 2553–2562. https://doi.org/10.1080/00222933.2019.1707893
Sajan S., Kumari D., Jahan S., Chakrabarty A., Kushwaha S., Sharma L.K., Tripathy B. & Chandra K. 2020. First record of the land operculate snail Cyclophorus pfeifferi Reeve, 1861 (Mollusca, Cyclophoroidea, Cyclophoridae) from India. Travaux du Muséum national d’Histoire naturelle “Grigore Antipa” 63 (1): 51–61. https://doi.org/10.3897/travaux.63.e48523
Saul M. 1966. Shell collecting in the limestone caves of Borneo. Conchologist’s Newsletter 19: 128–130.
Sil M., Basak R., Karanth K.P. & Aravind N.A. 2021. A new species of Pila (Gastropoda: Ampullariidae) from Mizoram, India. Molluscan Research 41 (3): 204–213. https://doi.org/10.1080/13235818.2021.1941575
Stoliczka F. 1871. Notes on terrestrial Mollusca from the neighbourhood of Moulmein (Tenasserim Provinces), with descriptions of new species. Journal of the Asiatic Society of Bengal, Part II 40 (2): 143-177. Available from https://biodiversitylibrary.org/page/35630965 [accessed 4 Apr. 2026].
Surya Rao K.V., Mookherjee H.P., Mitra S.C., Manna R.N. & Barua S. 2004. Mollusca. In: State Fauna Series 10: Fauna of Manipur, Part-3 (Invertebrates): 69–118. Zoological Survey of India, Kolkata,
Sutcharit C., Thach P., Chhuoy S., Ngor P.B., Jeratthitikul E., Siriwut W., Srisonchai R., Ng T.H., Pholyotha A., Jirapatrasilp P. & Panha S. 2020. Annotated checklist of the land snail fauna from southern Cambodia (Mollusca, Gastropoda). ZooKeys 948: 1–46. https://doi.org/10.3897/zookeys.948.51671
Tapparone Canefri C.M. 1883. Fauna malacologica della Nuova Guinea e delle isole adiacenti. Parte I, Molluschi estramarini. Annali del Museo Civico di Storia naturale di Genova 19: 1–313. Available from https://www.biodiversitylibrary.org/page/10812598 [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].
Thompson F.G. & Dance S.P. 1983. Non-marine mollusks of Borneo. II Pulmonata: Pupillidae, Clausiliidae. III Prosobranchia: Hydrocenidae, Helicinidae. Bulletin of the Florida State Museum, Biological Sciences 29: 101–152. https://doi.org/10.58782/flmnh.gwgk9850
Thompson F.G. & Upatham S. 1997. Vertiginid land snails from Thailand (Gastropoda, Pulmonata, Pupilloidea). Bulletin of the Florida Museum of Natural History, Biological Sciences 39 (7): 221–245. Available from https://ufdc.ufl.edu/UF00095785/ [accessed 4 Apr. 2026].
Tripathy B., Tudu P.C., Mukhopadhyay A., Sajan S.K., Sreeraj C.R., Gurumayum S.D., Ghosh A., Sultana R., Purushothaman J. & Siddique A. 2024. Checklist of Fauna of India: Mollusca. Version 1.0. Zoological Survey India. https://doi.org/10.26515/Fauna/1/2023/Mollusca
Van Benthem Jutting W.S.S. 1948. Systematic studies on the non-marine mollusca of the Indo-Australian Archipelago. I. Critical revision of the Javanese operculate land-shells of the families Hydrocenidae, Helicinidae, Cyclophoridae, Pupinidae and Cochlostomatidae. Treubia 19 (3): 539–604.
Van Benthem Jutting W.S.S. 1963. Non-marine Mollusca of West New Guinea. Part 1. Mollusca from fresh and brackish waters. Nova Guinea, Zoology 20: 409–521.
Vermeulen J.J. & Aiken S. 2020. Two land snail species of the Mekong Delta limestone hills (Cambodia, Vietnam): Aulacospira furtiva (Eupulmonata: Vertiginidae) and Georissa carinata (Neritimorpha: Hydrocenidae). Folia Malacologica 28 (3): 235–241. https://doi.org/10.12657/folmal.028.020
Vermeulen J.J. & Junau D. 2007. Bukit Sarang (Sarawak, Malaysia), an isolated limestone hill with an extraordinary snail fauna. Basteria 71: 209–220. Available from https://natuurtijdschriften.nl/pub/597351 [accessed 4 Apr. 2026].
Vermeulen J.J., Liew T.S. & Schilthuizen M. 2015. Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species. ZooKeys 531: 1–139. https://doi.org/10.3897/zookeys.531.6097
Vermeulen J. J., Luu H. T., Theary K. & Anker K. 2019. New species of land snails (Mollusca: Gastropoda: Caenogastropoda and Pulmonata) of the Mekong Delta Limestone Hills (Cambodia, Vietnam). Folia Malacologica 27 (1): 7–41. https://doi.org/10.12657/folmal.027.001
Wangkiri P., Panpong S., Jaijan N., Eiamsum-ang S., Chaijirawong R., Wongkamhaeng K. & Dumrongrojwattana P. 2018. First recorded of the microsnail genus Acmella (Gastropoda: Assimneidae) from Thailand. Burapha Science Journal 23: 1585–1596. Available from https://scijournal.buu.ac.th/index.php/sci/article/view/2271 [accessed 4 Apr. 2026].
Yen J.T.C. 1969. Fossile nicht-marine Mollusken-Faunen aus Nordchina. Sitzungsberichte der Österreichischen Akademie der Wissenschaften 177 (1/3): 21–64.
Zilch A. 1967. Die Typen und Typoide des Natur-Museums Senckenberg, 36: Mollusca, Assimineidae. Archiv für Molluskenkunde 96: 67–100.
Copyright (c) 2026 Nipu Kumar Das, Neelavar Ananthram Aravind

This work is licensed under a Creative Commons Attribution 4.0 International License.
Creative Commons Copyright Notices
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License (CC BY 4.0) that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are NOT PERMITTED to post their submitted work online (e.g., in institutional repositories or on personal websites) prior to publication, as it may lead to nomenclatural issues.
