Systematic status and phylogenetic relationships of the freshwater genus Balbiania (Rhodophyta)

The freshwater rhodophyte Balbiania investiens (Lenormand) Sirodot was coll ected as an epiphyte of Batrachospermum in small streams in England, Irelan d, and Germany, Unialgal cultures and field collections of Balbiania were a nalyzed in terms of their morphology, ultrastructure, and the DNA sequences of the genes coding for the large subunit of ribulose-1,5-bisphosphate car boxylase/oxygenase (rbcL) and 18S ribosomal RNA (rRNA), as well as the firs t internal transcribed spacer region (ITS1) of the rRNA genes. One of the m ajor distinguishing features of this genus is the production of spermatangi a on the tips of specialized, elongate cells, The spermatangia are cut off in a cluster together with similar nonspermatangial cells that are packed w ith starch granules. The only other rhodophyte genus with this: feature is Rhododraparnaldia; the two genera are differentiated from each other by the pattern of branching, substratum of attachment, and type of diploid phase. In the parsimony and distance trees inferred from the two gem sequences as well as in a combined parsimony tree, Balbiania and Rhododraparnaldia grou ped together on a well-supported branch separate from other taxa of the Bat rachospermales, Acrochaetiales, Nemaliales, and Palmariales. However, the t wo genera are positioned within a clade containing the last three orders. B ased on these findings, it is clear that the genus Balbiania is a valid tax on and that it is phylogenetically associated with Rhododraparnaldia. A new order is proposed, the Balbianiales. The two specimens of Balbiania analyz ed from England and Germany have identical sequences for all regions of DNA analyzed.