Taxonomic status of section Neuropogon in the genus Usnea elucidated by morphological comparisons and ITS rDNA sequences

Abstract

The taxonomic position of the Neuropogon group, as inferred from the morphology of representative species of the group and ITS sequences from Usnea antarctica and U. sphacelata, is discussed. Morphological observations revealed that the Neuropogon group does not have annular-pseudocyphellae, which are characteristic of the subgenus Dolichousnea, or a fistulose axis, which is characteristic of the subgenus Eumitria. In addition, the hypothecium of Neuropogon is thin, and the iodine reaction in the axis is negative. These features are consistent with those of the subgenus Usnea. Within the subgenus Usnea, Neuropogon is morphologically distinct from sections Usnea and Ceratinae (i.e. having a sphacelata-type cortex, black pigmentation of the upper thallus and a dark brown apothecial disc). The molecular data suggest that U. antarctica and U. sphacelata are members of the subgenus Usnea and are less closely related to subgenera Dolichousnea and Eumitria. The morphological and molecular phylogenetic analysis suggest that the Neuropogon group is a member of the subgenus Usnea at the level of a section, and the appropriate name for this group is subgenus Usnea section Neuropogon (Nees & Flot.) Mont.