Reinstatement of the Lancelet Name Asymmetron lucayanum, Recently Proposed as a Junior Synonym of Branchiostoma pelagicum (Cephalochordata)

Abstract

A recent proposal to reduce the binomen Asymmetron lucayanum Andrews, 1893 to the synonymy of Brachiostoma pelagicum Günther, 1889 lacked supporting evidence, and is considered flawed due to the uncertain taxonomic status of the latter. Examination of the holotype of B. pelagicum was hindered by its highly deteriorated state, to the extent that gonad condition and hence generic affinity could not be unequivocally determined. However, the description of gonads on both sides of the body in the original description suggests correct placement of the species in Branchiostoma. Furthermore, a published figure of a likely syntype (pelagic larva) of A. lucayanum showed the specimen to possess an elongated urostyloid process, such being absent in the (pelagic) holotype of B. pelagicum comparable in size and morphology with the former. It is proposed that Asymmetron lucayanum Andrews, 1893 be reinstated as a valid species.