Gracilaria cornea, the correct name for the western Atlantic alga hitherto known as G. debilis (Rhodophyta, Gigartinales)

Abstract

The species reported as Gracilaria debilis (Forsskål) Børgesen in the tropical western Atlantic is incorrectly named. Type material of G. debilis, from the Red Sea, differs from the Atlantic alga in several essential aspects of vegetative anatomy and in size of tetrasporangia. The next oldest name that has been applied to the Atlantic species, G. poitei (Lamouroux) J. Agardh, is unavailable as its basionym has previously been shown to be based on a species of Laurencia Lamouroux. A later name, G. wrightii (Turner) J. Agardh, is also considered inappropriate on the grounds that its protologue, in the absence of a type specimen, is thought to encompass more than one taxon and, moreover, is inconsistent with the alga in question. It is argued that a more recent binomial, G. cornea J. Agardh, is the correct name for this familiar species in the western Atlantic flora.