Abstract
A new species, Gayralia brasiliensis (Ulotrichales, Chlorophyta), is described from Brazil on the basis of ontogenetic, morphological, and molecular phylogenetic data. Liberation of zooids from the monostromatically bladed thalli occurred by disintegration of the zooidangium wall, releasing four biflagellate cells with prominent eyespots. Fusion of zooids was not observed. After zooid attachment, cell divisions gave rise to uniseriate filaments that developed into fan-shaped blades. Only asexual reproduction was observed; this took place through recycling of blades by germination of zooids. Phylogenetic analysis based on rDNA internal transcribed spacer (ITS) sequences showed that G. brasiliensis specimens formed a monophyletic group closely related to Monostroma nitidum and two unidentified monostromatic species from Japan and Tanzania. The genus Monostroma was polyphyletic in our analysis. ITS sequences also confirmed the presence of a second monostromatic species of Ulotrichales in the Brazilian coast, Gayralia oxysperma. There were overlapping morphological and life history traits between G. brasiliensis and G. oxysperma. However, these two species were clearly divergent based on ITS sequences and ontogeny.
©2013 by Walter de Gruyter Berlin Boston
