Suvarna S. Devi

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.

The deep-water euryplacid crab, Nectopanope rhodobaphes Wood-Mason in Wood-Mason & Alcock, 1891, is monotypic and was originally described from one female from the Bay of Bengal, 18°30′N 84°46′E, a location off the coast of Andhra Pradesh in India. This species has only been reported subsequently by Ng et al. (2019) from a first male specimen collected in southern India. Recent collections of N. rhodobaphes from off Tamil Nadu in India obtained good series of male and female specimens. The study of these specimens revealed a degree of size-associated variations in the structures of the anterolateral teeth, as well as branchial regions of the carapace and first male gonopods. Scanning Electron Microscopy was used to record the microstructures associated with the female sternum, gonopods and vulva. Also, recorded is its live colouration. The swollen branchial regions of this species are not due to parasitism but shown to be natural and could indicate it may occur in oxygen poor areas of the deep-sea.

Understanding the dynamics between native and invasive species in aquatic ecosystems is crucial for effective conservation and management. This study investigates the diet composition and niche overlap of the native paradise fish (Pseudosphromenus dayi) and the introduced three-spot gourami (Trichopodus trichopterus) in a coastal wetland in Kerala, India. Through a comprehensive diet analysis, the study aims to reveal trophic dynamics and potential competition between these coexisting species. A substantial diet overlap of 0.73 indicates significant resource sharing, particularly in detritus, plant matter, Chlorophyta, insect remains, Cyanophyta, and Crustacea, highlighting a pronounced interaction between the paradise fish and three-spot gourami. Abundant resources in the wetland likely alleviate interspecific competition, facilitating the coexistence of both species. The presence of microplastics in the gut of both species signals increased human intervention and plastic pollution in the watershed and wetland. These findings underscore the importance of considering dietary preferences and ecological behaviours in assessing interactions between native and invasive species. Effective management strategies are crucial to mitigate potential competition and maintain the ecological integrity of wetland habitats. Continuous monitoring of invasive freshwater fishes is recommended for early detection and the implementation of management plans to address potential threats.

Mursia spiridonovi Karasawa, 2018 known only from the western Indian Ocean, is the smallest species of the genus, measuring only 18 mm in carapace length. The species is redescribed from fresh material collected in Tamil Nadu in southern India. It is compared with similarly sized specimens of M. bicristimana Alcock and Anderson, 1894, all of which are immature. Mursia spiridonovi is characterised not only by its occurrence in shallow waters (less than 300 m depth) and small adult size but also by the prominently granular carapace and structure of the cheliped merus, male pleonal somites and gonopods.