A new species of Tortanus (Atortus) (Copepoda, Calanoida, Tortanidae) from Minicoy Island, southeastern Arabian Sea

A new specks of the planktonic calanoid copepod genus Tortanus, subgenus Atortus, is described from a coral reef lagoon of Minicoy Island, southeastern Arabian Sea. The new species is included in the tropicus group, which is mainly distributed in the tropical and subtropical waters of Southeast Asia. The species can be distinguished from all other species of the tropicus group by the asymmetrical fifth pedigerous somite with notched left margin and triangular lobe in the right, hyaline coupling device with larger left process, 2 ventrolateral spines in the genital compound somite, and caudal rami with 2 medial rounded processes in the female. In the male, serrated ridge of the right antennule slightly raised from the surface plane, beak-shaped medial process on the right fifth leg coxa, triangular medial process on the basis, and strongly curved subdistal seta on the left fifth leg. Mitochondrial cytochrome oxidase subunit I sequences of the specimens obtained with 642 base pairs confirmed the female-male correspondence and revealed the genetic identity of the species, which is herein compared with mtCOI sequences of congeners.