Anthracoidea obtusatae (Anthracoideaceae, Ustilaginales), a new smut fungus on Carex obtusata (Cyperaceae) from Central Asia

Anthracoidea species are highly host-specific smut fungi. Their host range is restricted to a single sedge species or sedge species belonging to the same or closely related sections. The species on Carex obtusata was referred to as Anthracoidea caryophylleae. However, the hosts of A. caryophylleae were reduced to carices in Carex sect. Mitratae, in its traditional circumscription. In the most recently proposed classification of Carex, C. obtusata has been placed within the Capitata Clade of C. subgen. Euthyceras. In order to clarify the taxonomic status of the Anthracoidea species on C. obtusata, we conducted a molecular study of specimens on C. obtusata and C. caryophyllea, using LSU rDNA sequences. It was found that the Anthracoidea species on C. obtusata is distinct from A. caryophylleae. A new species, Anthracoidea obtusatae on C. obtusata, is described and illustrated from Russia, based on a specimen from the Altay Mts. Its phylogenetic placement and affinities in Anthracoidea are analyzed. Anthracoidea obtusatae is distributed in Central Asia—the Northern Tian Shan Range (Zailiysky Alatau Range and Ketmen Ridge) and the Russian and Mongolian Altay Mts. A morphological examination of a specimen of Anthracoidea on C. obtusata from Canada found that its spore morphology did not match that of A. obtusatae. Additional collections and molecular study are required to clarify the taxonomic status of the North American Anthracoidea species on C. obtusata.