Genetic patterns in the calcified tropical seaweeds Halimeda opuntia, H. distorta, H. hederacea, and H. minima (Bryopsidales, Chlorophyta) provide insights in species boundaries and interoceanic dispersal

Abstract

The section Opuntia within the green seaweed genus Halimeda includes sprawling and pendant thalli composed of strongly calcified segments. Within this section, identification of Atlantic material is straightforward, but Indo-Pacific material is often difficult to key out. This is particularly true for specimens resembling H. opuntia, H. distorta, and H. hederacea; many specimens do not fit any type or are morphologically intermediate. The goals of the present study are to define morphologically and genetically distinct groups among such specimens and to assess phylogeographic patterns within these groups. Specimens were collected throughout the geographical and morphological range. Sequences..