Iris sanguinea var. tobataensis (Japanese name, “Tobata-ayame”) is endemic to Tobata, Kita-Kyushu City, Fukuoka Pref., Japan, and has been extinct in the wild. To revalidate the taxonomic placement of this Iris plant, we performed chemotaxonomic and molecular phylogenetic comparisons of this variety with I. sanguinea var. sanguinea. Two anthocyanins, delphinidin 3-O-[(4′′′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (An1) and petunidin 3-O-[(4′′′p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (An2), and twelve C-glycosylflavones, vicenin-2 (CF1), swertiajaponin X′′-O-hexoside (CF2), isoorientin (CF3), swertiajaponin (CF4), isovitexin 2′′-O-glucoside (CF5), swertisin 2′′-O-glucoside (CF6), isovitexin (CF7), swertisin (CF8), isovitexin 2′′-O-glucoside (CF9), acetylated flavoayamenins (CF10 and CF11), and acetylated swertisin (CF12), and two flavonols, myricetin 3-O-rhamnoside (FL1), and quercetin 3-O-rhamnoside (FL2), were isolated and characterized from the flowers and leaves of two I. sanguinea varieties. It was shown that flavonoid composition of their varieties is essentially the same except for CF11, which was detected only in the leaves of I. sanguinea var. tobataensis. Furthermore, a phylogenetic analysis using chloroplast matK gene and trnL-F intron DNA sequence data of Iris species including these two Iris sanguinea varieties was performed. The resultant tree indicated that two I. sanguinea varieties were closely related. These results supported that the taxonomic position of var. tobataensis as a variety of I. sanguinea is appropriate.
