Description of a new species of Arichlidon (Chrysopetalidae: Polychaeta) from the West Atlantic and comparison with the East Atlantic species Arichlidon reyssi

Arichlidon gathofi n. sp., comprising a cline of four closely related forms from four geographical locations down the West Atlantic coast of the Americas, based on the shape of their paleae, is described. This species is compared with the morphologically similar species A. reyssi (Katzmann, Laubier and Ramos, 1974) recorded from the East Atlantic coast and the Mediterranean. Variation of setal types within species is discussed and epitokous neurosetae are described in detail.