Phylogeography of the freshwater red alga Setacea puiggariana (Rhodophyta, Batrachospermales) in Brazil

Phylogeography of Setacea puiggariana, which is widely distributed in southern and south-eastern Brazil, with few records in South America and Africa, was investigated based on mitochondrial genetic markers: the cox2-3 spacer and the barcode region of cox1 gene. Ten stream segments were sampled across the known geographic distribution in Brazil, with a total of 65 individuals sequenced for the cox2-3 spacer and 30 for cox1. Six cox2-3 and eight cox1 haplotypes were observed among the individuals analyzed. Two haplotypes were found in one location for cox2-3 spacer, with all other locations having just one haplotype. Each of the cox1 haplotypes was found in a distinct location. Haplotype networks showed one haplotype occurring in most locations in southern and south-eastern Brazil for cox2-3 and revealed a relatively complex structure for cox1, with the same haplotype represented by individuals from two distant locations of southern and south-eastern Brazil. The low divergence observed among the Brazilian haplotypes supported the recognition of all collections as a single species, for both markers considering the geographic range sampled (maximum distance similar to 1000 km) as compared with previous studies at similar or broader geographic scales (> 2500 km). This study confirmed the general pattern found in Batrachospermales: that little variation is typically observed within a location and that most populations have one, rarely two haplotypes. In addition, we found no evidence of higher genetic divergences with increased geographic distance among haplotypes, which has also been reported in members of the Batrachospermales. (AU)