Systematics of the genus Halimeda(Bryopsidales, Chlorophyta) in Brazil including the description of Halimeda jolyana sp. nov.

Abstract:The genus Halimedahas a wide geographic distribution in tropical to subtropical regions of the world. Molecular studies have uncovered cryptic and pseudocryptic species as well as strong biogeographic signals in phylogenies. To date, the diversity of Brazilian Bryopsidales has been studied from only a morphological perspective. Here we revised the diversity of Brazilian Halimedabased on molecular data (DNA barcode assessments of the tufA marker and multigene concatenated phylogenies) as well as morphological observations. Of the seven recognized morphospecies, only three were confirmed by molecular data: Halimeda opuntia, H. simulansand H. incrassata. The remaining four species, referred to as H. aff. cuneata, H. aff. gracilis, H. aff. tunaand H. aff. discoidea, showed morphological similarities with known species, but their sequences did not group with sequences of specimens from type localities, indicating the presence of cryptic diversity. Among the four taxa, H. aff. cuneatais so far endemic to Brazil and is herein described as a new species, H. jolyana sp. nov. The remaining three (pseudo-)cryptic species require further studies using a global sampling design. The evolutionary and biogeographic origins of Brazilian Halimedaspecies are discussed based on new molecular phylogenetic hypotheses.