Scuttling in the highlands: Discovery of a new genus and species of freshwater crabs (Decapoda, Gecarcinucidae) from the Eastern Ghats, India

71 Scuttling in the highlands: Discovery of a new genus and species of freshwater crabs (Decapoda, Gecarcinucidae) from the Eastern Ghats, India Santanu Mitra1, Shibananda Rath2, Won-Kyo Jung3,4,5 , Hyun-Woo Kim3,4,6 , Shantanu Kundu7,8 1 Crustacea Division, Zoological Survey of India, Fire Proof Spirit Building, 27 Jawaharlal Nehru Road, Kolkata 700016, India 2 Freshwater Fish Section, Zoological Survey of India, Fire Proof Spirit Building, 27 Jawaharlal Nehru Road, Kolkata 700016, India 3 Marine Integrated Biomedical Technology Center, National Key Research Institutes in Universities, Pukyong National University, Busan 48513, Republic of Korea 4 Research Center for Marine Integrated Bionics Technology, Pukyong National University, Busan 48513, Republic of Korea 5 Major of Biomedical Engineering, Division of Smart Healthcare and New-Senior Healthcare Innovation Center (BK21 Plus), Pukyong National University, Busan, 48513, Republic of Korea 6 Department of Marine Biology, Pukyong National University, Busan 48513, Republic of Korea 7 Ocean and Fisheries Development International Cooperation Institute, College of Fisheries Science, Pukyong National University, Busan 48513, Republic of Korea 8 International Graduate Program of Fisheries Science, Pukyong National University, Busan 48513, Republic of Korea Corresponding author: Hyun-Woo Kim ([email protected]); Shantanu Kundu ([email protected]; [email protected]) Copyright: © Santanu Mitra et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International – CC BY 4.0). Research Article Abstract A new genus of gecarcinucid freshwater crab, Patithelphusa gen. nov., is described from the Shevaroy Hills, Yercaud, located in Salem District, Tamil Nadu, within the Eastern Ghats of India. This new genus is closely related to Baratha Bahir & Yeo, 2007 and Travancoriana Bott, 1969, but can be readily distinguished by a combination of morphological characters, including a relatively broad and shallow cervical groove, triangular bilobed median teeth on the epistomal median lobe, a blunt external orbital tooth with a relatively long outer margin, and a distinct G1 terminal segment terminating in a triangular tip. In addition, morphological characters together with molecular evidence from partial mitochondrial 16S rRNA gene sequences support the recognition of Patithelphusa yercaudensis sp. nov. as a distinct species, exhibiting a genetic divergence of 9.66% from its closest relative, Travancoriana schirnerae Bott, 1969. Phylogenetic analyses based on Bayesian inference and maximum-likelihood approaches recovered the newly described species as a wellsupported monophyletic clade, distinctly separated from other known gecarcinucid taxa from India and the geographically proximate region of Sri Lanka. With the addition of this new genus and species, the diversity of Indian gecarcinucid crabs increases to 112 species across 31 genera. Furthermore, biogeographic inferences suggest that the new genus and species may be isolated from its closest gecarcinucid relatives by the wide valleys and the Cauvery River system, which likely act as ecological and geographical barriers. These unique topographical features may restrict gene flow and limit dispersal among high-altitude, habitat-specialist decapods, providing a refuge that facilitates the evolution of novel taxonomic units in peninsular India. Key words: Crustaceans, Eastern Ghat, endemic species, integrated approach, new genus, new species, taxonomy Academic editor: Célio Magalhães Received: 21 April 2025 Accepted: 3 September 2025 Published: 28 October 2025 ZooBank: https://zoobank. org/E9EF4651-BA7E-40F1851F-E63238539486 Citation: Mitra S, Rath S, Jung W-K, Kim H-W, Kundu S (2025) Scuttling in the highlands: Discovery of a new genus and species of freshwater crabs (Decapoda, Gecarcinucidae) from the Eastern Ghats, India. ZooKeys 1257: 71–90. https://doi. org/10.3897/zookeys.1257.156494 ZooKeys 1257: 71–90 (2025) DOI: 10.3897/zookeys.1257.156494 72 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats Introduction The Indian subcontinent harbours a rich diversity of freshwater crabs (Crustacea: Decapoda), comprising approximately 172 species, which account for around 10% of the global brachyuran diversity (Pati et al. 2023; Mitra and Khamo 2024). Notably, the families Potamidae and Gecarcinucidae exhibit the highest species richness within this region (Pati and Pradhan 2020). Over the past century, the exploration and identification of freshwater crabs in the Indian subcontinent have been highly productive, significantly contributing to global knowledge (Klaus et al. 2014). However, these efforts remain incomplete, primarily due to inadequate sampling and limited taxonomic research in this historically significant biogeographic zone (Balss 1957). The Old World family Gecarcinucidae has a notable presence in India, with a total of 150 species documented worldwide (Mitra 2020; Pati et al. 2022; Mitra and Khamo 2024). Within the Indian subcontinent, 111 species spanning 30 genera have been documented, predominantly restricted to the peninsular region (Brandis and Sharma 2005; Bahir and Yeo 2007; Ng et al. 2008; Cumberlidge et al. 2009; Pati and Vargila 2019; Pati et al. 2019a, b; Mitra 2020; Raj et al. 2025). Some of these species primarily inhabit elevations exceeding 1000 meters within the Western Ghats, with some known solely from their type locality (Bahir and Yeo 2007). Due to the limited availability of occurrence data, most of these species are categorized as ‘Data Deficient’ on the IUCN Red List of Threatened Species (Cumberlidge et al. 2009). The Indian subcontinent also accommodates one of the taxonomically oldest genera, Barytelphusa Alcock, 1909, from which four additional genera—Travancoriana Bott, 1969, Baratha Bahir & Yeo, 2007, Vanni Bahir & Yeo, 2007, and Vela Bahir & Yeo, 2007—were later segregated based on a combination of morphological characters, including the presence of long flagella on the exopods of the third maxilliped and a relatively elongated distal segment of the second gonopod (G2). These genera are distinguished from other extant genera by their unique morphological traits and are primarily distributed in the Indian Peninsula (Bahir and Yeo 2007). The genera Vela and Baratha are distinguished from Vanni and Travancoriana by their relatively convex carapace. The genus Vela is unique among its closely related species in possessing a distinctly convex carapace, a distinct groove at the suture between thoracic sternites 3 and 4, a slender male abdomen, and a telson that is 1.4 times longer than its proximal width. In contrast, Baratha, while sharing a convex carapace and a distinct groove at the suture between thoracic sternites 3 and 4, has a relatively broader male abdomen and a telson that is 1.1 times longer than its proximal width. The genus Vanni, characterized by a squarish and slightly convex carapace in frontal view, lacks a well-defined suture between thoracic sternites 3 and 4 and exhibits less distinct postorbital cristae, setting it apart from its related genera. Meanwhile, Travancoriana differs from all related genera by its low, transverse carapace, poorly marked suture between thoracic sternites 3 and 4, and strongly developed postorbital cristae. Despite these distinct morphological differences, molecular data for these genera remain scattered, complicating the understanding of gecarcinucid genetic diversity in peninsular India (Bahir and Yeo 2007). In addition to rigorous taxonomic investigation, molecular phylogenetic analyses suggest that Gecarcinucidae originated within the Indian subconti- 73 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats nent during the Cretaceous/Early Paleogene period. This evolutionary insight is thought to be linked to the tectonic convergence of the Indian subcontinent with Eurasia. Hence, the systematic and phylogenetic studies on gecarcinucid crabs in the Indian subcontinent have gained significant momentum in recent years (Bossuyt et al. 2004; Bahir and Ng 2005; Bahir and Yeo 2005; Daniels et al. 2006; Klaus et al. 2006, 2009, 2010, 2013; Beenaerts et al. 2010). However, the continuous discovery of new gecarcinucid taxa underscores the incomplete understanding of their basal phylogenetic relationships. This necessitates further faunistic investigations to accurately assess their diversity and evolutionary history, particularly among montane crabs. This study is based on the hypothesis that additional, previously unreported gecarcinucid genera and species exist beyond their currently recognized biogeographic distribution in peninsular India, necessitating confirmation through an integrated approach. Thus, a recent zoological survey in the Eastern Ghats has led to the discovery of a new genus and a novel species within the family Gecarcinucidae. Material and methods Sampling and morphological examination Freshwater crab specimens were hand-collected from a muddy microhabitat adjacent to a rocky stream in Manjakuttai, Shevaroy Hills, Yercaud, Salem District, Tamil Nadu, within the Eastern Ghats range (Fig. 1). Two whole-body specimens and body parts from four additional specimens were preserved in 70% ethanol. Morphological measurements and terminology followed previous studies (Ng 1988; Ng and Tay 2001; Guinot et al. 2013; Davie et al. 2015). Specimens were photographed using a Nikon P900 camera and examined under a Leica EZ4 stereozoom binocular microscope. The following abbreviations are used for morphological examination: CW = carapace width; CL = carapace length; FW = frontal width; CH = carapace height; P2–P5 = second to fifth ambulatory legs; S1–S8 = thoracic sternites 1–8; G1 = male first gonopod; G2 = male second gonopod; ZSIC = Zoological Survey of India, Crustacea Section; ZRC = Zoological Reference Collection, Lee Kong Chian Natural History Museum, Singapore. Comparative materials examined Baratha pushta Bahir & Yeo, 2007: holotype male (cw 23.2 mm, cl 16.1 mm), ZRC 2003.0234; Loc. Vaguvurai estate, on Munnar-Pollachi, Kerala, India, 10°11'07.5"N, 77°06'40.0"E, alt. 1290 m — Baratha peena Bahir & Yeo, 2007: holotype male (cw 18.4 mm, cl 13.2 mm), ZRC 2003.0235; Paniyar estate, on Kumarly–Munnar road, Kerala, India, 10°00'47.0"N, 77°11'29.5"E, alt. 1260 m. DNA extraction, PCR amplification, and sequencing The genomic DNA was extracted from the holotype and paratype specimens, as well as from body parts of four additional specimens using the standard phenol–chloroform isoamyl alcohol method (Sambrook and Russell 2001). The extracted DNA was visualized through 1% agarose gel electrophoresis. The published primer pair (16L29: 5′-YGCCTGTTTATCAAAAACAT-3′and 16H37: 74 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats Figure 1. Map showing the collection and type locality of Patithelphusa yercaudensis gen. et sp. nov. An inset photo illustrates the habitat of this newly described taxon in the Eastern Ghats of India. 5′-CCGGTYTGAACTCAAATCATGT3′) was used to amplify the widely applied partial 16S rRNA segment (⁓560 bp) for the identification of crab species (Klaus et al. 2009). The 25 ml PCR mixture comprises 10 pmol of each primer, 20 ng of DNA template, 1X PCR buffer, 1.0–1.5 mM of MgCl2, 0.25 mM of each dNTPs, and 1 U of Platinum Taq DNA Polymerase High fidelity (Invitrogen). The PCR reaction was performed in an Applied Biosystems MiniAmp Plus Thermal Cycler with the published thermal profile. The PCR products were purified using a QIAquick Gel Extraction Kit (Qiagen) according to the standard protocol. The cycle sequencing was executed by using a BigDye Terminator v. 3.1 Cycle Sequencing Kit (and 3.2 pmol of each primer on the Thermal Cycler). The products were cleaned using a BigDye X-terminator kit with standard protocol and subsequently bidirectionally sequenced by a ABI 3500 Genetic Analyzer (Applied Biosystems) at InBOL Healthcare Pvt Ltd, Kolkata, India. Sequence quality check and dataset preparation The study obtained both forward and reverse chromatograms from the holotype and paratype samples. The noisy parts of each chromatogram were trimmed at both ends, and a quality value (> 40) was used to screen the consensus sequenc- 75 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats es through SeqScanner v. 1.0 (Applied Biosystems). The annotated sequences were verified through nucleotide BLAST search and subsequently contributed to GenBank for free public access. A total of 45 sequences of the gecarcinucids species distributed in India were retrieved from GenBank (Bossuyt et al. 2004; Daniels et al. 2006; Klaus et al. 2006; Shih et al. 2009; Beenaerts et al. 2010; Klaus et al. 2013; Klaus et al. 2014; Shashi et al. 2023; Wolfe et al. 2024) (Suppl. material 1: table S1). Additionally, nine sequences from two genera (Pastilla Ng & Tay, 2001 and Mahatha Ng & Tay, 2001) originating from Sri Lanka were incorporated into the dataset, as the region is geographically close to southern India (the actual study sites) and the faunal elements of both regions often exhibit close co-evolutionary affinities, including freshwater crabs (Bossuyt et al. 2004; Beenaerts et al. 2010). These sequences, along with the newly generated ones, were aligned using ClustalX to create a combined dataset for genetic distance and phylogenetic analyses. In addition, the DNA sequences of Candidiopotamon penglai (GenBank accession no. OR346860; family Potamidae) were included as an outgroup taxon in the present analyses (Shih et al. 2023). Genetic distance and phylogenetic analysis The pairwise interand intragroup (species and genus) genetic distance was estimated through Kimura-2-parameter (K2P) in MEGA v. 11 (Tamura et al. 2021). The model selection (GTR+G+I) was conducted using JmodelTest v. 2, which yielded the lowest BIC (Bayesian Information Criterion) score (Darriba et al. 2012). Bayesian phylogenetic inference (BI) was conducted using MrBayes v. 3.1.2 (Ronquist and Huelsenbeck 2003), implementing a general time-reversible model with gamma-distributed rate variation and a proportion of invariable sites (nst = 6). The analysis employed four Metropolis-coupled Markov chain Monte Carlo (MCMC) chains, comprising one cold chain and three hot chains. A total of 1,000,000 generations were run, with tree sampling occurring every 100 generations, and the initial 25% of sampled trees were discarded as burn-in. Further, the maximum-likelihood (ML) phylogenetic tree was generated using the PhyML v. 3.0 web server (http://www.atgc-montpellier.fr/phyml/), incorporating 1000 bootstrap samples (Guindon et al. 2010). The final ML and BI phylogenies were visualized using the iTOL v. 4 web server (https://itol.embl.de/) (Letunic and Bork 2007). Results and discussion Taxonomic lineage Subphylum: Crustacea Class: Malacostraca Order: Decapoda Family Gecarcinucidae Rathbun, 1904 Patithelphusa gen. nov. https://zoobank.org/F7C2F210-A26D-4C76-8ED9-9E4CCB3AE1C6 Type species. Patithelphusa yercaudensis sp. nov., by present designation. Diagnosis. Carapace distinctly broader than long, dorsal surface distinctly convex, lateral margins with many short oblique striae (Fig. 2A); dorsal surface 76 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats Figure 2. Patithelphusa yercaudensis sp. nov. holotype male (cw 29.22 mm, cl 20.83 mm) (ZSIC-CR 396): A. Dorsal view of the carapace; B. Frontal view of the cephalothorax; C. Ventral view of the body; D. Left third maxilliped with exopods; E. Pleon; F. Upper part of the sternum and pleon; G. Major cheliped hand. 77 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats distinctly convex in frontal view (Fig. 2B); external orbital angle widely triangular, blunt, outer margin serrated, 4.5 times of inner margin (Fig. 2A); epibranchial tooth short, distinct notch between epibranchial tooth and outer margin of external orbital tooth; cervical groove well demarcated in all course, broad and shallow anteriorly, relatively deep and narrow posteriorly, not reaching to the postorbital cristae; epistomal median lobe with distinct triangular tooth, tip bilobed; third maxilliped exopods with long flagellum (Fig. 2D); suture between S2/S3 shallow and broad, not reaching to lateral margins of sternum; suture between S3/S4 shallow and broad, not interrupted by any ridge, reaching to lateral edge of sternum. Sixth pleonal segment of male slightly broader than long (Fig. 2C, E, F); G1 subterminal segment relatively slender, basally broad; terminal segment cone shaped, elongated, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle, with some long setae, tip triangular, not sharp. G2 c. 1.2 times longer than G1, subterminal segment long, basally broad, terminal segment slightly shorter than half of subterminal segment (Fig. 3A–C). Etymology. The genus is named after eminent crustacean taxonomist, Dr Sameer Kumar Pati, for his valuable contribution to freshwater crab taxonomy in India. The gender is neuter. Remarks. The new genus Patithelphusa shares similarities with only four gecarcinucid genera, Baratha, Travancoriana, Vanni and Vela, by having a combination of characters: exopods of third maxilliped with long flagellum, and the Figure 3. Patithelphusa yercaudensis sp. nov. holotype male (cw 29.22 mm, cl 20.83 mm) (ZSIC-CR 396). A. Ventral view of the left G1; B. Dorsal view of the left G1; C. Left lateral view. 78 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats distal segment of G2 is relatively long. Patithelphusa gen. nov. can nevertheless be separated from Baratha by its anterolateral and posterolateral region of carapace dorsal surface with many horizontal and oblique striae (Fig. 2A) (vs. anterolateral and posterolateral region of carapace dorsal surface smooth in Baratha; figs 19a, 21a, Bahir and Yeo 2007); external orbital angle widely triangular, blunt (Fig. 2A) (vs. external orbital angle sharp, produced; figs 19a, 21a, Bahir and Yeo 2007); pleonal somite six of male distinctly broader than long (Fig. 2C, E) (vs. pleonal somite six of male squarish to slight longer than broad; figs 18b, 19c, 21c, Bahir and Yeo 2007); antennular fossae rectangular (Fig. 2B) (vs. eye shaped, medially broad, gradually narrower in both ends, figs 19b, 21b, Bahir and Yeo 2007); G1 terminal segment relatively longer, tip blunt (Fig. 3A, B) (vs. G1 terminal segment relatively shorter, cone shaped, tip pointed; figs 18c– g, 20a–e, Bahir and Yeo 2007). Patithelphusa gen. nov. can be separated from Travancoriana by several morphological characters: the dorsal surface of carapace distinctly convex in frontal and as well as in dorsal view in Patithelphusa gen. nov. (Fig. 2A, B) (vs. carapace dorsal surface slightly convex in frontal view in Travancoriana; taf. 4, figs 38, 39, Bott 1970; fig. 8a, b, Bahir and Yeo 2007); somite six of male pleon distinctly broader than long (Fig. 2C, E) (vs. somite six of male pleon longer than broad; taf. 4, fig. 40, Bott 1970; figs 7d, 8c, Bahir and Yeo 2007); outer margin of external orbital tooth serrated (Fig. 2A) (vs. outer margin of external orbital tooth smooth; taf. 4, fig. 39, Bott 1970; fig. 8a, Bahir and Yeo 2007); epigastric cristae separated from postorbital cristae by a small gap (Fig. 2A) (vs. epigastric cristae confluent with postorbital cristae; taf. 4, fig. 39, Bott 1970; fig. 8a, Bahir and Yeo 2007); epibranchial tooth small but discernible, cleft distinct (Fig. 2A) (vs. epibranchial tooth indistinct, cleft not visible; taf. 4, fig. 39, Bott 1970; fig. 8a, Bahir and Yeo 2007). Outer orbital margin of epibranchial tooth is distinctly straight in Patithelphusa (Fig. 2A) (vs. outer orbital margin of epibranchial tooth distinctly convex in Travancoriana; taf. 4, fig. 39, Bott 1970; fig. 8a, Bahir and Yeo 2007); G1 terminal segment cone shaped, elongated, 0.4 times of subterminal segment, tip triangular, not sharp (Fig. 3A, B) (vs. G1 terminal segment relatively longer c. 0.3-0.6 times of subterminal segment, tip acute; figs 7 f–h, 16 f-I, Bahir and Yeo 2007). The genus Vanni superficially resembles Patithelphusa gen. nov., but the latter exhibits several distinguishing characteristics: carapace almost squarish in Vanni (fig. 32a, Bahir and Yeo 2007), while distinctly wider than long in Patithelphusa gen. nov. (Fig. 2A); carapace flat or slightly convex in frontal view (fig. 32b, Bahir and Yeo 2007), however the carapace of the new genus is convex in frontal and dorsal view (Fig. 2A, B); suture between S2/S3 indistinct or slightly visible in Vanni (fig. 32b, Bahir and Yeo 2007), while S2/S3 is distinctly visible in Patithelphusa gen. nov (Fig. 2C, F); suture between sternites S3/S4 indistinct (fig. 32b, Bahir and Yeo 2007) vs. S3/S4 distinct and reaches the lateral margins of the sternum in Patithelphusa gen. nov (Fig. 2C, F); G1 terminal segment cone shaped, elongated, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle, with some long setae; tip triangular, not sharp (Fig. 3A, B) (vs. G1 stout, terminal segment relatively short, c. 0.3-0.35 times of subterminal segment, subterminal segment gently tapering towards terminal segment; figs 31c–f, 33a, b, 35c–f, 33d–e, Bahir and Yeo 2007). 79 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats Genus Vela is closely related to the new genus, though there are some distinct morphological features that easily separate these two genera. The epigastric cristae is smooth in Vela (fig. 46a, Bahir and Yeo 2007), while it is distinctly rugose in Patithelphusa gen. nov. (Fig. 2A); postorbital cristae and epigastric cristae are confluent (fig. 46a, Bahir and Yeo 2007), however postorbital cristae and epigastric cristae are not confluent in Patithelphusa (Fig. 2A); sixth somite of the male pleon distinctly longer than broad (figs 45B, 46c, Bahir and Yeo 2007), however sixth somite broader than long in Patithelphusa (Fig. 2E); branchial region relatively swollen (fig. 46a, Bahir and Yeo 2007), while branchial region gently convex in Patithelphusa gen. nov. (Fig. 2A); G1 terminal segment cone shaped, 0.4 times of subterminal segment, inner margin straight, outer margin convex in middle (Fig. 3A, B) (vs. G1 terminal segment more slender and long, 0.45-0.5 times of subterminal segment, outer margin not convex; figs 45c–e, 47b–e: Bahir and Yeo 2007). Patithelphusa yercaudensis sp. nov. https://zoobank.org/F0FECF3D-2B9D-44A7-865C-01D11ACBA122 Figs 2, 4 Etymology. This species is named after its type locality, Yercaud, a town and hill station in Salem District in Tamil Nadu, India. Located in the Shevaroy Hills in the Eastern Ghats, it is situated at an altitude of 1515 m. Used as a noun in apposition. Suggested common name: Yercaud crab. Type specimens. Holotype: • 1 male (cw 29.22 mm, cl 20.83 mm, ch 12.41 mm, fw 8.36 mm). Locality: Manjakuttai, Shevaroy Hills, Yercaud, District. Salem, Tamil Nadu, India, 11°49'37.6"N, 78°13'59.3"E; elevation 1504 m; date of collection, 27. 02. 2024; collected by S. Mitra; ZSIC Reg no. CR 396. Paratype: • 1 female (cw 21.20 mm, cl 15.25 mm, ch 8.82 mm, fw 5.82 mm); collection data same as above; ZSIC Reg. no. CR 397. Colourations. Dark brown to chocolate colour in live condition. The cheliped and ventral colouration is light brown mixed with light yellow. The female is a little darker than the male. Distribution. The species is known only from the type locality, Yercaud (Fig. 1) of the District Salem, Tamil Nadu, India. Diagnosis. See genus Diagnosis. Description. Carapace distinctly broader than long (cw/cl =1.4), deep (ch/ cl=0.6), dorsal surface gently convex in frontal view; epigastric cristae low, rugose, slightly anterior to postorbital cristae, postorbital cristae sharp extended up to epibranchial tooth; external orbital angle widely triangular, blunt, outer margin serrated, 4.5 times of inner margin; supraorbital margin sinuate, granulated (Fig. 2A), no notch between infraorbital margin and external orbital tooth (Fig. 2B); epibranchial tooth short, distinct notch between epibranchial tooth and outer margin of external orbital tooth; anterolateral margin distinctly convex, cristate, shorter than posterolateral margins, anterolateral region distinctly convex with some oblique striae, posterolateral margin gently concave. Cervical groove well demarcated along its course, broad and shallow anteriorly, relatively deep and narrow posteriorly, not reaching to the postorbital cristae; mesogastric groove shallow, I-shaped; H-shaped groove distinct (Fig. 2A); 86 ZooKeys 1257: 71–90 (2025), DOI: 10.3897/zookeys.1257.156494 Santanu Mitra et al.: Freshwater Crab of Eastern Ghats Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Use of AI No use of AI was reported. Funding This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (RS2021-NR060118). Author contributions Conceptualization, S.M. and S.K.; Data curation, S.M. and S.R.; Formal analysis, S.M. and S.K.; Funding acquisition, W.K.J. and H.W.K.; Investigation, S.M. and S.R.; Methodology, S.M. and S.R.; Project administration, H.W.K. and S.K.; Resources, H.W.K. and S.K.; Software, H.W.K. and S.K.; Supervision, H.W.K. and S.K.; Validation, S.M. and S.R.; Visualization, W.K.J. and H.W.K.; Writing-original draft, S.M. and S.K.; Writing-review and editing, W.K.J. and H.W.K. Author ORCIDs Santanu Mitra https://orcid.org/0000-0002-3247-9293 Shibananda Rath https://orcid.org/0000-0002-3547-3743 Won-Kyo Jung https://orcid.org/0000-0002-1615-750X Hyun-Woo Kim https://orcid.org/0000-0003-1357-5893 Shantanu Kundu https://orcid.org/0000-0002-5488-4433 Data availability The examined specimens are vouchered in the National Zoological Collections of the Crustacea Division, Zoological Survey of India, and can be re-examined upon obtaining the necessary permissions from the authors and the Director Zoological Survey of India, Kolkata. The DNA sequences generated in this study (Accession numbers PP973477– PP973482) have been submitted to the global NCBI GenBank database (https://www. ncbi.nlm.nih.gov/) and are freely accessible for future research. References Bahir MM, Ng PKL (2005) Descriptions of ten new species of freshwater crabs (Crustacea: Brachyura: Parathelphusidae: Ceylonthelphusa, Mahatha, Perbrinckia) from Sri Lanka. The Raffles Bulletin of Zoology. 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Bootstrap support of each node is indicated numerically. table S1. The dataset used in the present study was prepared using both the generated DNA sequences and sequences retrieved from the GenBank database. Copyright notice: This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited. Link: https://doi.org/10.3897/zookeys.1257.156494.suppl1