Thaxterogaster pallidirimosus
Thaxterogaster pallidirimosus is a species of mushroom-forming fungus in the family Cortinariaceae, first described in 2014 as a member of genus Cortinarius before being reclassified in 2022. It is characterized by its medium-sized fruit bodies with whitish to cream, hygrophanous caps that develop brownish-yellow centres and streaks as they age, and club-shaped to nearly cylindrical stipes that are initially white before turning pale brown. This fungus is found throughout Fennoscandia, Russia, and parts of the United States, where it grows on the ground in boreal, mesic, and mixed forests, often in association with birch trees.
Taxonomy
The fungus was described as new to science in 2014 and classified as Cortinarius pallidirimosus from specimens collected in Finland. The type specimen was collected on 17 August 1995 by I. Kytövuori at Tsieskuljohka, near Kevo in the municipality of Utsjoki, Inari, within a mesic heath forest dominated by Betula and Pinus, with occasional moist depressions. The holotype is preserved at the herbarium of Helsinki University, and an isotype is housed at the New York Botanical Garden.The fungus was classified in the subgenus Phlegmacium of the large mushroom-forming fungal genus Cortinarius. The specific epithet pallidirimosus refers to the pale, streaked cap. Thaxterogaster caesiophylloides is a closely related sister species. In 2022 the species was transferred from Cortinarius and reclassified into the newly erected genus Thaxterogaster based on genomic data.