Cryptic diversity of Tetraclita squamosa complex (Crustacea, Cirripedia) in Asia: description of a new species from Singapore

barnacles of the genus Tetraclita are common space occupiers in the intertidal zone of rocky shores in tropical and subtropical waters (Newman and Ross 1976). In spite of their eco-logical importance, there is taxonomic confusion about these barnacles because of their high levels of morphological variation. Darwin (1854) consid-ered T. squamosa to constitute a complex with 12 subspecies. Over the years, a number of his sub-species have been raised to specific rank, based on morphological and molecular analyses (e.g., Achituv and Mizrahi 1987, Hasegawa et al. 1996, Ross 1999). Tetraclita squamosa is characterized by having green parietes (Pilsbry 1916, Yamaguchi, 1987) and has a wide distribution throughout the Indo-Pacific (Newman and Ross 1976, Ren and Liu 1979). A recent study in East Asia revealed the presence of cryptic species with-in this taxon (Chan et al. 2007). Tetraclita squamosa collected from the northwestern Pacific (Taiwan, and Okinawa and Honshu, Japan) is mor-phologically and genetically differentiated fro