taxonID	type	description	language	source
038887E9FFB273194701FE55FB3FA849.taxon	type_taxon	Type species Hydrocena pyxis W. H. Benson, 1856 (Thyet Myo, Myanmar), by original designation.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	description	urn: lsid: zoobank. org: act: BA 54 A 3 F 3 - 52 D 5 - 4 CA 5 - 8949 - 3 C 03 FFC 0 FAF 8 Figs 3, 7	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	etymology	Etymology Named after the state where the species has been collected.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	materials_examined	Type material Holotype INDIA • preserved in alcohol; Meghalaya, Krem Puri [‘ Krem’ means ‘ cave’ in Khasi language of Meghalaya]; 25.278599 ° N, 91.559557 ° E; 1261 m a. s. l.; 28 Dec. 2022; Nipu Kumar Das leg.; ZSI / SRC / LM 2161. Paratypes INDIA • 2 specs (preserved in alcohol); same data as for holotype; ZSI / SRC / LM 2162 a, ZSI / SRC / LM 2162 b.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	description	Measurements (in mm) Holotype: SH 1.91, SW 1.56, SH / SW 1.22, AH 0.91, AW 0.94, AH / AW 0.97, SpH 0.98, SpW 1.35, PrW 0.47. Paratype ZSI / SRC / LM 2162 a: SH 2.26, SW 1.72, SH / SW 1.31, AH 1.03, AW 0.98, AH / AW 1.05, SpH 1.21, SpW 1.44, PrW 0.52. Description of the shell Shell dextral, small, oval, turbinate; spire acuminate; colour orangish-red; shell sculpture meshed pattern, spiral ribs present, somewhat strong, very densely arranged, 3 – 4 spiral ribs / 0.1 mm on the body whorl, and around regularly spaced across shell surface immediately after protoconch, sometimes distorted by radial ribs or growth lines, radial ribs present, irregular and weakly sculptured across the shell; suture well-impressed with slightly extended shoulder; umbilicus narrow; whorls 3.5, convex; protoconch / teleoconch transition zone distinct; protoconch dark brownish, round and globular, nearly smooth with pits, whorls 1.5; aperture ovate, oblique or sub-vertical; peristome simple, thin and continuous, parietal lip angular, palatal and basal lips or edges roundish; columellar callus dark brownish, prominent and oblique; operculum oval, calcareous, multispiral with growth lines.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	diagnosis	Differential diagnosis Georissa meghalayaensis sp. nov. shows similarity in shell shape with G. sarrita (W. H. Benson, 1851), G. mawsmaiensis Das & Aravind, 2021, G. pyxis (W. H. Benson, 1856), and G. hungerfordi Godwin-Austen, 1889, but differs in having mesh-like striations across the shell surface, unlike the others, with strong or sharp spiral striations and in shell colour (yellowish in G. sarrita vs orangish-red in G. meghalayaensis). There are also denser spiral striations in G. meghalayaensis compared to the four above-mentioned species. The mesh-like shell sculpture pattern of G. meghalayaensis is similar to the scaly G. niahensis Godwin-Austen, 1889 (Niah Hills, Borneo), but it differs in the shape of the first whorl of the scaly teleoconch. Georissa meghalayaensis is slightly smaller, with fewer whorls, and less densely arranged spiral striations on the shell compared to G. digitinota Klongkaew, Poeaim & Dumrongrojwattana, 2024 (Satun Province, Thailand). Georissa monterosatiana Godwin-Austen & Neville, 1879 (Perak State, Malaysia) differs from G. meghalayaensis in having a small, elongate-conic shell with strong, regularly spaced spiral ribs on the shell surface. A detailed comparison of various shell features of G. meghalayaensis with its congeners is provided in Table 1, and the shell size comparison is shown in Fig. 7 A.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	biology_ecology	Habitat and distribution Live individuals of Georissa meghalayaensis sp. nov. were collected at the edge of the cave entrance on a wet, moss-covered rocky wall, with 50 % canopy cover. Georissa meghalayaensis is known only from the type locality.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB2731B4711FD06FCE1A9DB.taxon	discussion	Remarks The holotype and paratypes differ slightly in shell sculpture. The body whorl of the paratype is finer and more polished than that of the holotype. Additionally, the aperture neck of the paratypes shows stronger, more distinct, and densely packed radial ribs, whereas the holotype has only very fine ribs or a nearly polished neck, which are nearly invisible to the naked eye.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB07310477CFB9BFDD6A8D5.taxon	description	Figs 4, 7	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB07310477CFB9BFDD6A8D5.taxon	materials_examined	Material examined INDIA • 8 shells; Mizoram, Champhai district, Tuipui, approximately 2 km NW of the bridge over Tuipui River; 23.46694 ° N, 93.2525 ° E; 851 m a. s. l.; 31 Jan. 2019; Nipu Kumar Das leg.; AT / 2019 / LS 5010 to 5017.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB07310477CFB9BFDD6A8D5.taxon	description	Measurements (in mm) Shell 1 (AT / 2019 / LS 5010, Fig. 4 A – F): SH 1.63, SW 1.12, SH / SW 1.45, AH 0.68, AW 0.69, AH / AW 0.98, SpH 0.95, SpW 0.99, distance between spiral ribs on body whorl (apertural view) 0.09, PrW 0.35, OH 0.51, OW 0.38. Shell 2 (AT / 2019 / LS 5011, Fig. 4 G – M): SH 1.74, SW 1.24, SH / SW 1.40, AH 0.73, AW 0.74, AH / AW 0.99, SpH 1.00, SpW 1.10, distance between spiral ribs on body whorl (apertural view) 0.10, PrW 0.37. Description of shell Shell dextral, small, oval, turbinate; spire acuminate; colour yellowish; shell sculpture spiral ribs present, strong, widely arranged and at nearly regular interval across shell surface, 6 very strong spiral ribs on body whorl above aperture (in apertural view), spiral ribs sometimes distorted or discontinuous due to growth lines, very densely spaced spiral ribs on basal part of body whorl or in umbilical view, radial ribs absent, weak growth lines across shell, mesh visible in umbilical view, nearly indistinct on rest of shell; suture well-impressed with narrow shoulder; umbilicus narrow; whorls 3.5 – 4, convex; protoconch / teleconch transition zone distinct; protoconch brownish or horny, round and globular, nearly smooth with evenly distributed pits, Wh 1.25; aperture round or slightly ovate, oblique or sub-vertical; peristome simple, thin and continuous, parietal lip angular, palatal and basal lips or edge roundish; columellar callus prominent and oblique, shiny or sometimes transparent; operculum thick, oval, multispiral or concentric, with characteristic calcareous slender peg on inner side or surface, OH 0.51 mm, OW 0.38 mm.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB07310477CFB9BFDD6A8D5.taxon	biology_ecology	Habitat and distribution The shells of G. sarrita were found in the soil-leaf litter sample collected near Tuipui village, Champhai district, Mizoram, whereas the type material of the species was originally reported from mosses in deep valleys near Cherrapunji, Meghalaya (Benson 1851). The temperature at the soil, soil leaf litter depth, and % canopy cover at the new collection site were 21 – 22 ° C, 2 – 3.5 cm, and 30 %, respectively. Other gastropod species, namely Glessula sp. and Tanychlamys sp., were also present at the collection site. The site was located by the roadside near a dry stream with abundant leaf litter.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB07310477CFB9BFDD6A8D5.taxon	discussion	Remarks The present material is slightly smaller (SH 1.63 – 1.74 mm, SW 1.12 – 1.24 mm) than the dimensions given in the original description (SH 2 mm, SW 1.25 mm) (Benson 1851). Benson’s collection, including the syntype specimen (UMZC I. 103725. A), is worn and exhibits whitish or yellowish colouration, whereas the new shells from Mizoram are reddish. This new collection represents the first record of Georissa from Mizoram, NE India.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB973124702FB8AFED8AFDC.taxon	type_taxon	Type species Cyclostoma tersum W. H. Benson, 1853 by monotypy (in muscis arborum ad Musmai, prope Cherra-Poonje).	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB973124702FB8AFED8AFDC.taxon	discussion	Remarks Recently, Vermeulen et al. (2015) divided the genus Acmella into two informal groups based on shell sculpture: Group 1 characterized by predominant radial sculpture, and Group 2 defined by predominant spiral sculpture, or radial and spiral sculpture about equally strong, or virtually no sculpture present. Similarly, Das et al. (2021) summarised the different kinds of shell sculpture in species of Acmella, including the typical patterns: radial, irregular, or radial with irregular + weak spiral sculpture, thereby indicating that the variation in shell sculpture extends beyond the two groups recognised by Vermeulen et al. (2015).	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	description	urn: lsid: zoobank. org: act: 8 FD 532 B 9 - DD 53 - 49 F 0 - AB 01 - 35 DC 95701 C 7 E Figs 6 – 7	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	etymology	Etymology Named in honour of William H. Benson, the pioneer of Indian malacology. He has contributed significantly to the taxonomy of Indian land and freshwater molluscs.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	materials_examined	Type material Holotype INDIA • shell; Meghalaya, Krem Puri; 25.278599 ° N, 91.559557 ° E; 1261 m a. s. l.; 28 Dec. 2022; Nipu Kumar Das leg.; ZSI / SRC / LM 2163. Paratypes INDIA • 1 shell; same data as for holotype; ZSI / SRC / LM 2164 • 6 shells; Meghalaya, Arwah Cave; 25.301939 ° N, 91.72691 ° E; 168 m a. s. l.; 22 Dec. 2022; Nipu Kumar Das leg.; ZSI / SRC / LM 2165 a to ZSI / SRC / LM 2165 f.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	description	Measurements (in mm) Holotype SH 1.37, SW 1.09, SH / SW 1.26, AH 0.60, AW 0.51, AH / AW 1.18, SpH 0.77, SpW 0.97. Description of the shell Shell dextral, minute, conical-oval, turbinate, shiny and somewhat transparent; spire acuminate or conical; colour white; shell sculpture indistinct, fine and densely spaced spiral and radial ribs or growth lines across shell surface, 5 – 7 spiral ribs / 0.1 mm on body whorl, fine radial ribs clearly visible on neck of aperture; suture moderate to well-impressed with slightly extended shoulder; umbilicus open and wide, umbilicus width 0.06 – 0.13 mm, slightly covered by angular callus extension of columellar lip; whorls 4.25 – 4.5, convex; protoconch / teleoconch transition zone distinct; protoconch shiny, whitish, obtuse, nearly smooth with pits, Wh 1.25, PrW 0.28 – 0.31 mm; aperture ovate-lunate, oblique or sub-vertical; peristome simple, somewhat thick and continuous, parietal lip straight and sometimes indistinct, and merged with body whorl, parieto-palatal juncture distinct and sharply angulated, palatal, basal and columellar lips or edges roundish; columellar lip thick and roundish; operculum unknown.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	diagnosis	Differential diagnosis Acmella bensoni sp. nov. shows a close morphological similarity to A. tersa in shell shape, but differs by having a smaller, whitish shell, with well-impressed sutures and indistinct sculpture, characterised by fine, densely spaced spiral and radial ribs or growth lines across the shell surface. The shells of A. bensoni, A. moreletiana G. Nevill, 1878, A. roepstorffiana G. Nevill, 1878, and A. hyalina Theobald & Stoliczka, 1872 are shiny and transparent; however, they differ in shell sculpture and size according to the type images and original descriptions. Acmella hyalina is the smallest, with a smooth shell sculpture, unlike A. moreletiana, which has a distinct sculpture around the umbilicus in a very characteristic manner, with regular, distinct plications beneath the suture. Acmella roepstorffiana possesses distinct, strong, closely, and evenly or regularly spaced striae that are thread-like, oblique, and more prominent toward the base, especially around the umbilical region. Acmella minutissima Maassen, 2000 from Western Sumatra shows close morphological similarity to A. bensoni, sharing a somewhat similar shell sculpture consisting of fine radial lirae between the spiral lirae. However, A. minutissima differs in having a much smaller shell size (SH 0.8 mm), a smaller shell aperture, fewer whorls, and a less elongate spire than A. bensoni. A detailed comparison of various shell features of A. bensoni with its congeners is provided in Table 2, and the shell size comparison is shown in Fig. 7 B.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	biology_ecology	Habitat and distribution The shells of Acmella bensoni sp. nov. were found on both dry and wet cave walls, approximately 4 – 12 m inside the cave from the entrance. Acmella bensoni is reported only from the type localities. Arwah Cave, Meghalaya, attracts a large number of tourists and tends to be crowded. Artificial lighting installed throughout the cave creates a very bright environment inside. Additionally, man-made staircases have been built at the entrance to facilitate tourist access.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
038887E9FFB9731347C5F991FAFAAD9F.taxon	discussion	Remarks The shells of A. bensoni sp. nov show a slight morphological variability. Some shells are slightly larger and less ovoid, with a well-impressed suture and a slightly extended shoulder compared to the holotype.	en	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. European Journal of Taxonomy 1060: 1-27, DOI: 10.5852/ejt.2026.1060.3284, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/3284/14486
