Hildenbrandia jigongshanensis (Hildenbrandiaceae, Rhodophyta), a new freshwater species described from Jigongshan Mountain, China

Abstract

A new freshwater red alga, Hildenbrandia jigongshanensis, is described from materials collected on the surface of rocks in flowing water from Jigongshan Mountain, China. This new species is distinguished from the other freshwater members by significantly larger cell dimensions (9.8–19.6) × (9.9–10.4) μm and filament height (364–409 μm). Phylogenetic analysis based on sequences of the rbcL gene and the construction of 18S ribosomal RNA (rRNA) secondary structure demonstrated the separation between H. jigongshanensis and other freshwater Hildenbrandia species. Specimens of H. jigongshanensis formed a clade divergent from H. rivularis group with robust support values based on rbcL gene sequences, and was in the basal position relative to the monophyletic H. rivularis, whereas the species H. angolensis was paraphyletic and distributed among both the freshwater and marine clades. Primary structure of 18S rRNA produced phylogenetic tree with low resolutions and unresolved relationship among the freshwater Hildenbrandia species due to high sequence conservation. Secondary structure based on 18S rRNA sequences distinguished the new species by absence of 3 helices compared with common structure of H. rivularis. This species description brings the total number of recognized freshwater Hildenbrandia species in China to two.