Abstract
A significant limitation when testing the putative single origin of primary plastids and the monophyly of the Archaeplastida supergroup, comprised of the red algae, viridiplants, and glaucophytes, is the scarce nuclear and organellar genome data available from the latter lineage. The Glaucophyta are a key algal group when investigating the origin and early diversification of photosynthetic eukaryotes. However, so far only the plastid and mitochondrial genomes of the glaucophytes Cyanophora paradoxa (strain CCMP 329) and Glaucocystis nostochinearum (strain UTEX 64) have been completely sequenced. Here, we present the complete mitochondrial genomes of Gloeochaete wittrockiana SAG 46.84 (36.05 kb; 33 protein-coding genes, 6 unidentified open reading frames [ORFs], and 28 transfer RNAs [tRNAs]) and Cyanoptyche gloeocystis SAG 4.97 (33.24 kb; 33 protein-coding genes, 6 unidentified ORFs, and 26 tRNAs), which represent two genera distantly related to the "well-known" Cyanophora and Glaucocystis. The mitochondrial gene repertoire of the four glaucophyte species is highly conserved, whereas the gene order shows considerable variation. Phylogenetic analyses of 14 mitochondrial genes from representative taxa from the major eukaryotic supergroups, here including novel sequences from the glaucophytes Cyanophora tetracyanea (strain NIES-764) and Cyanophora biloba (strain UTEX LB 2766), recover a clade uniting the three Archaeplastida lineages; this recovery is dependent on our novel glaucophyte data, demonstrating the importance of greater taxon sampling within the glaucophytes.