Appukuttannair Biju Kumar

The genus Agarna Schioedte & Meinert, 1884, is reviewed and rediagnosed. The female, male and transitional stages of Agarna cumulus (Haller, 1880), the senior synonym of the type species, are redescribed based on the newly designated lectotype and additional material collected from the Caribbean parasitising doctorfish, Acanthurus chirurgus (Bloch, 1787), blue tang surgeonfish Acanthurus coeruleus Bloch & Schneider, 1801, and barber surgeonfish Acanthurus bahianus Castelnau, 1855. The types and non-type specimens of Agarna malayi Tiwari, 1952, were re-examined and found to differ from the generic characters of Agarna . We thus propose Gibbothoa gen. nov. distinguished by the following combination of characters: an asymmetrical and hunched body, with one side of the body more or less straight and the other side strongly recurved; an irregular pereonite 1 anterior margin, anterolateral margin conspicuously incised, produced into narrow projections; pereonites all asymmetrically distorted; the pleon wider than pereonite 7; coxae more or less equal on both sides; pereonites 2–7 abruptly increasing in width toward one side, but laterally not expanded from the pereopod basis; the pleotelson broadly rounded and symmetrical; the antenna thicker than the antennula; a maxilliped without an oostegite lobe; and the pleopod 5 endopod with fleshy lobes. Agarna pustulosa (Pillai, 1954) is placed into synonymy with Gibbothoa malayi (Tiwari, 1952) comb. nov., based on morphological and molecular examination of fresh specimens collected from the type host. The taxonomic status of Agarna bengalensis Kumari et al., 1990, is also assessed, and the species is regarded as a species inquirendum .

We present the first comprehensive account of the reproductive biology of Kani maranjandu Kumar, Raj & Ng, 2017, a unique tree-dwelling gecarcinucid freshwater crab endemic to the southern Western Ghats of Kerala, India. As the only known exclusive arboreal freshwater crab, the species exhibits remarkable reproductive adaptations associated with a phytotelmic lifestyle. We investigated the mating patterns, gonadosomatic index (GSI), breeding seasonality, sex ratio, fecundity, gonadal maturation, size at first maturity, parental care, and life cycle through monthly sampling from September 2021 to August 2022. The available evidence suggests that K. maranjandu appears to exhibit a soft-female mating system, with mating occurring between post-moult females and intermoult males from January to February. Peak GSI values were observed in December for males (0.9059 ± 0.1235) and January for females (2.4102 ± 0.1641), indicating a distinct breeding season extending from December to May, coinciding with pre-monsoon rains. The overall sex ratio was 1F:0.79M. Mean fecundity was low (23.3 ± 5.61), consistent with phytotelmic habitat constraints, but increased significantly with female body size (R² = 0.91). Juvenile- carrying females appeared from March to June, peaking in April. Histological analyses identified five ovarian stages and three testicular stages, revealing typical gametogenic progression. Reproductive organs were compact and dorsolaterally arranged, possibly facilitating arboreal mobility. Size at first maturity was estimated at 29.97 mm CW in males, 32.57 mm CW in females. Females guarded the eggs and hatchlings within tree holes for 40 ± 4.5 days until juvenile release during the onset of monsoon rains in June. These reproductive traits appear to be adapted to the spatially isolated, predator-sheltered canopy microhabitats. The species’ relatively low fecundity, habitat specialization, and restricted distribution may increase its vulnerability to habitat disturbance and changing rainfall regimes, emphasizing the need for baseline data for conservation and long-term monitoring.

A new genus, Clavatovillus n. gen., is established for Anamathia beauchampi Alcock & Anderson, 1894, a poorly known epialtid crab originally described from western Bay of Bengal. Examination of fresh specimens shows that the species differs from Crocydocinus Lee, Richer de Forges & Ng, 2019 s. str., where it was placed provisionally, as well as allied genera, in that the epi- and mesobranchial regions of the carapace are distinctly inflated medially, compressing the urogastric region, the outer margin of basal antennal article is strongly convex, the merus of the third maxilliped is not auriculiform, the male pleon is proportionately narrower, the male sternite 8 is clearly visible when the pleon is closed, the margins of the ambulatory merus, carpus, and propodus are smooth, rounded, without crista, and densely lined with distinct clavate setae. The rediscovery of this rare deep-sea taxon after more than a century highlights the underestimated diversity and taxonomic complexity of majoid crabs in the Indian Ocean.

This study documents the first recorded occurrence of six commercially important grouper fish species (Teleostei: Perciformes: Epinephelidae) from the Lakshadweep Islands, India. The species documented in this study are the Snubnose grouper Epinephelus macrospilos (Bleeker, 1855), Brownspotted grouper Epinephelus chlorostigma (Valenciennes, 1828), Dotted grouper Epinephelus epistictus (Temminck and Schlegel, 1842), Slender grouper Anyperodon leucogrammicus (Valenciennes, 1828), White-edged lyretail Variola albimarginata Baissac, 1953 and Oblique-banded grouper Epinephelus radiatus (Day, 1868). Both morphological examination and molecular analysis were carried out to characterize and confirm the identity of these species. This investigation represents the first documentation of these six grouper species from the Lakshadweep Islands. The results enhance current understanding of the marine biodiversity of the region and provide valuable information for the management and sustainability of its commercially important fisheries.

Subterranean biodiversity continues to be poorly known as a result of uncertainties, challenges and hazards associated with sampling in microhabitats such as aquifers and caves. Focusing on the narrow, lateritic aquifers and associated groundwater habitats in the Western Ghats freshwater ecoregion (southern peninsular India), we investigate the genetic diversity of an enigmatic group of eel-like fishes (family Synbranchidae). A maximum-likelihood phylogenetic analysis based on mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences recovered these synbranchid eels into two distinct clades comprising genera Ophichthys (fossorial eels ‘with eyes’) and Rakthamichthys (aquifer-dwelling ‘blind’ eels). Additionally, three species-delimitation approaches (based on the mitochondrial cox1 gene), revealed the presence of 11 Evolutionarily Distinct Lineages (EDLs) within Rakthamichthys separated by an inter-lineage divergence between 5.8–20.3%, and an intra-lineage divergence between 0–4.5%. Rakthamichthys in southern peninsular India exhibited a distribution pattern comprising both restricted-range and wide-ranging lineages. Fossorial eels of the genus Ophichthys, on the other hand, are widely distributed in southern peninsular India, with clear geographical boundaries separating the two known species. The genetic network of Rakthamichthys and Ophichthys revealed multiple haplotypes within various EDLs, with a large number of mutations separating the haplotypes within, and between species and/or lineages. Though represented by high levels of genetic divergence revealing the potential existence of at least 11 EDLs, their remarkable morphological uniformity combined with a complex distribution pattern makes it difficult to assign known species names to various Rakthamichthys lineages. Most subterranean habitats in southern peninsular India are under severe anthropogenic threats. Therefore, resolving the taxonomy of, and developing conservation actions for groundwater-dependent species is a priority, for which we suggest future steps.

A new species of gecarcinucid freshwater crab Pilarta vaman sp. nov. is described from Gavi, Southern Western Ghats, Kerala, Southern India. The new species differs from P. anuka Bahir & Yeo, 2007, by its more quadrate carapace with an extremely shallow cervical groove that is almost undiscernible, as well as the proportionately longer terminal article and more convex outer margins of the subterminal article of the male first gonopod; from P. aroma Pati, Rajesh, Raj, Sheeja, Kumar & Sureshan, 2017, by its low subtruncate inner angle of the carpus of the cheliped, and the narrower proximal part of the subterminal article and shape of the terminal article of the male first gonopod; and from P. punctatissima Pati, Rajesh, Raj, Sheeja, Kumar & Sureshan, 2017, by the carapace and the surfaces of the chela being weakly punctate, the male pleonal somite 6 has the lateral margins gently concave and the overall male first gonopod being more elongate.