Lactarius aff. brunneoviolaceus M.P. Christ.

Barge, Edward G. & Cripps, Cathy L., 2016, New reports, phylogenetic analysis, and a key to Lactarius Pers. in the Greater Yellowstone Ecosystem informed by molecular data, MycoKeys 15, pp. 1-58 : 20-22

Taxon classification Fungi Russulales Russulaceae

8. Lactarius aff. brunneoviolaceus M.P. Christ. Figure 10

Description.

Pileus 30-60 mm in diameter, convex to slightly depressed–convex, smooth, viscid, faintly zonate, brownish with lavender hues, marbled, whitish near margin; margin incurved and faintly tomentose when young. KOH on pileus cuticle green. Lamellae adnate, crowded, cream, staining violet where damaged. Stipe 25-30 × 20-25 mm, clavate, smooth, white with hoary coating, staining violet where damaged, hollow. Context not observed. Latex white, unchanging, staining tissue violet. Odor sweet. Taste mild, becoming slightly bitter.

Basidiospores 8-12 × 6.5-8 µm, Q = 1.2-1.5, broadly ellipsoid to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 40-90 × 8-12 µm, scattered to numerous, subfusiform to fusiform; apex mucronate. Cheilomacrocystidia 40-88 × 7-12 µm, numerous, fusiform; apex mucronate.

Ecology and distribution.

Lactarius brunneoviolaceus occurs in arctic-alpine areas with Salix . The species described here was found growing near tree line (krummholz spruce present) on the Beartooth Plateau amongst Salix reticulata and Salix planifolia , late summer.

Specimens examined.

U.S.A. MONTANA: Custer County, Beartooth Plateau, Birch Site, among krummholz Picea engelmannii , Salix reticulata and Salix planifolia , 15 Aug 2014, CLC3098 (MONT).

Discussion.

More collections and molecular data from this species are needed, however, this is the first report of a species from the GYE, and to the best of our knowledge, North America, bearing affinities to the arctic-alpine Salix associate Lactarius brunneoviolaceus . Unfortunately, high quality sequence data was not obtained for this collection, and only a small portion of ITS1 could be used for phylogenetic analyses, which placed it with Lactarius brunneoviolaceus . Morphologically, it is also a close match, except that the pileus of the species described here stains green with KOH, which is not historically mentioned for Lactarius brunneoviolaceus . It is possible that the pileus of Lactarius brunneoviolaceus stains green in KOH as well but that it has not been thoroughly tested. In CLC2133 from Norway, another specimen closely matching Lactarius brunneoviolaceus which was examined, the pileus (of dried material) also stained green in KOH.

This species is very closely related to Lactarius montanus (Figure 2A), however, the latter features slightly smaller basidiospores (7-10.5 × 6-8 µm, although sometimes to 12 µm long), and is typically below tree line with conifers. Lactarius pallidomarginatus , which is also closely related, has lighter colored, less violaceous pilei that do not stain green in KOH, and smaller basidiospores (8-10 × 6.5-8 µm).