Fig. 4

Core families F01–F25 of streptophyte mitochondrial group II introns. Cladogram of streptophyte mitochondrial group II introns categorized into core families F01-F10 (left panel) and F11-F25 (right panel) as described in the text. Occurrence of introns in the different streptophyte clades is given with a clade code before the respective intron label with underscores indicating absence in a given clade as shown in the cladogram legend (bottom right). Small letters indicate cases of possibly late intron gain within a given clade and ‘x’ indicates pseudogenization or complete loss of the respective host gene, respectively. Presence of maturases is indicated with square symbols distinguishing variable degrees of conservation of the maturase RT and X domains and the En domains as shown in the legend (bottom right). Evidently defect intron fossils are labeled with”g2f” and indicated in italics, the identification of such fossil intron inserts in intergenic sequences of mitogenomes is indicated with the respective family number