Finding Nemo! Description of a New Species of Branchial Fish Parasitic Cymothoid, Elthusa Schioedte and Meinert, 1884 (Crustacea: Isopoda), infesting Callionymus filamentosus Valenciennes, 1837 from the Northern Indian Ocean.

PURPOSE: Specimens of Elthusa from trashfish of the Indian SW coast were described as a new parasitic cymothoid, Elthusa nemo sp. nov., (Crustacea: Isopoda). Later, the branchial cavity of the Blotchfin dragonet Callionymus filamentosus Valenciennes, 1837 were documented as its micro- and macro-habitat (host). METHODS: Fresh/live specimens of unidentified cymothoid samples were collected from the trash fishes obtained from Neendakara (08°30.0' N 76°53.30' E) fish landing centre, Kollam district, Kerala state, southwest coast of India. After a long search for the host species, we recovered the isopod from the branchial cavity of the deep-sea fish Callionymus filamentosus Valenciennes, 1837 (Callionymiformes: Callionymidae). The new species is described and illustrated based on ovigerous females. RESULTS: Elthusa nemo sp. nov., has the following sets of combinations of characters: body slightly twisted, elongated, dorsal surfaces smooth, nearly twice as long as greatest width; pleon short, ~ 14% body length, 0.8 times as wide as pereon maximum width; widest at pleonite 2 and narrowest at pleonite 1; only pleonite 1, laterally overlapped by pereonite 7 posterolateral expansion and coxa 7; presence of appendix masculina on pleopod 2; uropods 0.8 times as the length of pleotelson; antenna with two plumose setae on article 4. CONCLUSION: Elthusa nemo sp. nov., is the sixth species of the genus known from Indian waters.

New Genus and Two New Species of Semiterrestrial Crabs (Decapoda: Brachyura: Gecarcinucidae) from the Southern Western Ghats, India.

One new genus and two new species of semiterrestrial freshwater crabs are described from the Southern Western Ghats mountain range in India: Pavizham gavi gen., sp. nov. and Rajathelphusa brunnea sp. nov. The carapace of Pavizham n. gen. is superficially similar to Baratha and Snaha described from the same region, but it can be distinguished from Baratha in having no visible postorbital cristae, complete sutures between male thoracic sternites 2 and 3, the possession of a triangular male pleon and the elongate terminal segment of the male first gonopod; and from Snaha by the presence of a long flagellum on the exopod of the third maxilliped, a complete suture separating male thoracic sternites 2 and 3, and its triangular male pleon. Rajathelphusa brunnea sp. nov. can easily be distinguished from congeners in possessing a distinctly more slender and elongate male first gonopod.

Description of a New Genus with Two New Species of Freshwater Crab (Decapoda: Brachyura: Gecarcinucidae) from the Southwestern Ghats, India.

A new genus of freshwater crab, Rajathelphusa gen. nov., and two species, R. ala sp. nov. (type species) and R. muni sp. nov., are described from the Kerala part of the Western Ghats biodiversity hotspot, India. The new genus is superficially similar to Arcithelphusa and Cylindrotelphusa from the same hotspot, but can easily be distinguished by the following suite of carapace and gonopod characters: an inflated carapace with distinct epigastric and postorbital cristae; the third maxilliped exopod has a long flagellum; male sternites 2 and 3 separated by a shallow median groove while sternites 3 and 4 are completely fused, demarcated by shallow oblique grooves; a male first gonopod that is almost straight with a short distal conical distal segment; and a male second gonopod that is as long as the first gonopod with a long and slender distal segment. The two new species can be differentiated from each other by the lateral margins of male pleonal somite 6 and the structure of the male first gonopod.

Amazonian invaders in an Asian biodiversity hotspot: Understanding demographics for the management of the armoured sailfin catfish, Pterygoplichthys pardalis in Kerala, India.

Invasion of armoured catfish, Pterygoplichthys spp., is a major threat to global aquatic biodiversity, and developing effective strategies for their control and eradication is both a concern and a research priority. A length-based population assessment of invasive Pterygoplichthys pardalis in southern India, a hotspot for endemic aquatic biodiversity, indicated that rapid growth, high growth performance index and continuous recruitment have aided their successful invasion. Increasing fishing pressure on the adults is not adequate for population management, and only targeting young individuals (<30 cm) will result in overexploitation and population collapse.

A new species of freshwater crab of the genus Oziotelphusa Müller, 1887 (Crustacea: Decapoda: Brachyura: Gecarcinucidae) from Tamil Nadu, southern India.

A new species of gecarcinucid freshwater crab of the genus Oziotelphusa Müller, 1887, is described from stationary or slow-flowing bodies of water in Keeriparai near Nagercoil, in the state of Tamil Nadu in southern India. Oziotelphusa ravi, new species, is distinguished from its congeners by several distinct characters: the median tooth of the posterior margin of epistome forms a distinct bilobed tip in frontal view, the male pleonal somite 6 is narrowly trapezoidal and slightly wider than long with the lateral margins concave, the terminal segment of the male first gonopod is distinctly bent laterally (along the longitudinal axis) at an angle of about 45°, and the proximal part of the outer margin of the subterminal segment of the male first gonopod has a prominent deep concavity.