Macrosporophycos sahyadricus (Batrachospermales, Rhodophyta), a new genus and species of freshwater red algae from the Western Ghats of India

A new genus of freshwater red algae, Macrosporophycos, and a new species, M. sahyadricus, are described from the Periyar River in the southern part of the Western Ghats, Kerala, India. Macrosporophycos shares distinctive characteristics with Montagnia, such as straight carpogonial branches having involucral filaments forming a rosette around the carpogonia, and pedunculate carposporophytes. However, the two genera have a raw genetic distance of 16.4%-17.0% for rbcL, and 24%-26.7% for COI-5P genes. The new species, Macrosporophycos sahyadricus, also possesses large, elongated, pear-shaped carposporangia. Phylogenetic analyses based on the concatenated rbcL and COI-5P recovered M. sahyadricus as a distinct lineage, sister to Acarposporophycos from South America. However, these genera are distinct from each other in their morphology. The morphological similarity, coupled with the high levels of genetic difference between Macrosporophycos and Montagnia, suggest convergent evolution in morphology. The recent records of new red algal taxa, including the discovery of this new genus, suggest that the Indian subcontinent continues to be under-explored and is in need of integrative taxonomic research supported by large-scale sampling.