Description of Elthusa aquabio sp. n. (Crustacea: Isopoda: Cymothoidae), a branchial fish parasitic isopod from Indian waters

A new branchial fish parasitic cymothoid species, Elthusa aquabio sp. n. (Crustacea: Isopoda: Cymothoidae), is described based on the ovigerous female collected from an unknown host obtained from trash fishes from the south-west coast of India. The species Elthusa aquabio sp. nov. has the following characteristics: (1) body slightly twisted, elongated, dorsal surfaces smooth, 1.8 times as long as greatest width; (2) pleon short, 0.16 times as long as total body length, pleon 0.75 times as wide as pereion maximum width; (3) widest at pleonite 3 and most narrow at pleonite 1; (4) coxae 5-7, flat, broad, laterally expanded; (5) uropods 0.7 times as the length of pleotelson; (6) pereopods 1-3 propodus inner lateral margin with small, robust spines; (7) antenna with 10 articles.