Two new species of Tortanus (Atortus) (Copepoda, Calanoida, Tortanidae) from the Andaman Islands

Two new species of the planktonic copepod genus Tortanus, subgenus Atortus, are described from inter- to sub-tidal water of South Andaman Island, India. The new species are assigned to the tropicus group sensu Othman (1987) and distinguished from the other members of the group by the characteristic morphology of the pair of posterior dorsolateral processes on the fifth pedigerous somite in the female and the antennule and leg 5 in the male. An analysis of previous records of the tropicus species group indicates their sporadic occurrence combined with high species richness in Southeast Asia, suggesting future discovery of even more species by sampling with finer geographic and habitat coverage.