Notes on the marine algae of the International Biosphere Reserve Seaflower, Caribbean Colombia XI: Pseudobryopsis basiglabra sp. nov. (Pseudobryopsidaceae, Chlorophyta)

Background and Aims: The genus Pseudobryopsis currently encompasses seven species distributed in tropical and warm-temperate waters. They are separated from the morphological similar genus Trichosolen by chloroplast morphology and the presence of a plug at the base of the gametangia. During the 2022 Seaflower Scientific Expedition, an undescribed species of the green algal genus Pseudobryopsis was collected. The objective of this study is to describe this new species, discuss its morphological features, and provide a taxonomic key for the genus. Methods: The species was collected by snorkeling in September 2022 in the southernmost part of the Archipelago of San Andrés, Providencia, and Santa Catalina, located in the southwestern Caribbean Sea, off the coast of Nicaragua, at Bolívar cay (south-southeast cay) at a depth of 2.1 m. The sample was preserved in 96% ethanol solution and identified in the Marine Biology Laboratory of the Universidad Nacional de Colombia in Bogotá. The specimen was deposited in the herbarium JIW in the Biology Department of the Universidad Nacional de Colombia, Bogotá, Colombia. Key results: A new species, Pseudobryopsis basiglabra, is described. Despite its superficial resemblance to P. thikkodiensis and P. gracilis, the characteristic unbranched habit of the vegetative thallus and the position of its gametangia on the main axes allow P. basiglabra to be distinguished from other known species of the genus. Conclusions: Pseudobryopsis basiglabra sp. nov. has sufficient diagnostic features to consider it as a new species for science.