Cerceis insolita n. sp., a new species of sphaeromatid isopod crustacean from the coastal waters of Pakistan

Cerceis insolitan. sp. (Isopoda, Sphaeromatidae), from the rocky intertidal region of Manora Island, Karachi coast, Pakistan, is described. The species can be identified on the basis of the following characters: antenna 1, pleon, pleotelson, coxal plates, pleopods 4 and 5, and notably by the unusual female pereopod 1 merus being short, transversely expanded, with the distolateral angle laterally produced into circular structure; carpus short, transversely expanded, propodus stout, curved laterally, with convex medial and concave lateral margins, dactylus subtriangular, well-developed unguis and accessory unguis. Right pereopod 7 long, slender, merus distomedial angle produced into medially directed lobe. Left pereopod 7 merus distomedial angle produced posteriorly. The species is described and illustrated.