Wrangelia gordoniae, a new species of Rhodophyta (Ceramiales, Wrangeliaceae) from the tropical western Atlantic

Abstract

On the basis of comparative morphological and molecular analyses, a new red algal species in the genus Wrangelia (Wrangeliaceae, Ceramiales) is described from the tropical western Atlantic. Distinctive characteristics of the proposed new species, W. gordoniae, include: overall habit; built up pseudoparenchymatous cortex that is composed of 2, and in localized sites up to 3, layers of cortical cells, with the outermost layer incomplete, composed of smaller, irregular-shaped cells; and spermatangial heads with 5-6 (-7) involucres, each consisting of a single elongate cell. Analyses of SSU sequences of specimens of Wrangelia from Puerto Rico further support the presence of four genetically distinct entities. In addition to numerous recent collections, a number of herbarium specimens from different Caribbean locales previously identified as "W. penicillata" are now recognized to be W. gordoniae. The new species is compared morphologically with other Wrangelia species that also have 5 whorl branchlets per segment and a cortex that partially or wholly covers their axes. A key to the tropical western Atlantic species of Wrangelia is provided.