Phylogenetic relationship of Batrachospermum species (Batrachospermales, Rhodophyta) from coastal streams in French Guiana

Abstract

M.L. Vis, W.B. Chiasson and R.G. Sheath. 2005. Phylogenetic relationship of Batrachospermum species (Batrachospermales, Rhodophyta) from coastal streams in French Guiana. Phycologia 44: 441–446.Eighteen samples of eight Batrachospermum species from collections in French Guiana, South America, were analysed utilizing RUBISCO large subunit (rbcL) gene sequence data in order to assess phylogenetic placement and evaluate intra-specific sequence variation among continents. Five species, B. ambiguum (two samples), B. gracillimum, B. guyanense, B. intortum and B. nodiflorum (two samples), belong to section Contorta. Section Aristata was represented by B. macrosporum (six samples) and B. cayennense (three samples) and Section Turfosa by B. turfosum (two samples). Maximum parsimony, distance, maximum likelihood and Bayesian analyses produced phylogenetic trees with similar topologies. The species from section Contorta were in a well-supported clade with previously sequenced taxa of that section. However, the subsectional classification sometimes applied to this section was not supported by the molecular data. Samples of B. macrosporum and B. cayennense were sister to each other, but they were on long branches and there was only moderate support in the Bayesian analyses for this node. Potentially, the two subsections of section Aristata may be raised to sectional status with further investigation of other closely related taxa. Batrachospermum turfosum is the only species presently sequenced from section Turfosa and these samples formed a well-supported clade on a long branch, which was variously related to other batrachospermalean taxa in the analyses. Three of the species, B. ambiguum, B. cayennense and B. macrosporum, showed little to no variation within species for the French Guiana samples, but varied considerably from previously published sequences of samples from different continents. In contrast, the B. turfosum samples differ little from a North American sample.