Lactarius controversus Pers.

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 : 24-26

Taxon classification Fungi Russulales Russulaceae

10. Lactarius controversus Pers. Figure 12

Description.

Pileus 50-120 mm in diameter, depressed–convex to infundibuliform, smooth, viscid to dry, faintly zonate, zones narrow and often more conspicuous near the margin, cream to pale tan–cream, often with tan to rust brown blotches; margin incurved and faintly short–tomentose when young, becoming glabrous and straight to undulating in age. Lamellae adnate to subdecurrent, crowded, creamy pink to pink–tan, discoloring tawny light brown where damaged. Stipe 25-50 × 17-28 mm, short, equal to tapering toward the base, subviscid to dry, smooth, ± scrobiculate, white, discoloring pale yellow to tawny light brown where damaged, solid, becoming hollow. Context white, discoloring tawny light brown. Latex scarce, white, unchanging. Odor faint to slightly spermatic. Taste slowly acrid.

Basidiospores 5.5-8 × 4.5-5.5 µm, Q = 1.2-1.5, broadly ellipsoid to ellipsoid; ornamentation forming a nearly complete reticulum. Pleuromacrocystidia 25-50 × 3-7 µm, scarce, cylindric to fusiform; apex acute to moniliform. Cheilomacrocystidia 25-40 × 3-6 µm, scarce, cylindric to fusiform; apex rounded to acute.

Ecology and distribution.

Widely distributed in the northern hemisphere with Populus (aspen), Salix , and possibly Betula . In the GYE it occurs in montane areas near Populus tremuloides , summer and fall.

Specimens examined.

U.S.A. IDAHO: Teton County, Teton Mountains, under Populus tremuloides , CLC290 ( MONT). MONTANA: Carbon County, near Red Lodge, along Rock Creek, under Populus tremuloides , 8 Aug 2015, EB110-15 ( MONT); Park County, Cinnabar Basin, under Populus tremuloides , 18 July 1990, CLC106 ( MONT), 2 Aug 1990, CLC116 ( MONT), 11 Sept 1991, CLC262 ( MONT), 13 July 1992, CLC462 ( MONT); Silverbow County, Butte, East Ridge, under Populus tremuloides , 15 Aug 1993, CLC699 ( MONT). WYOMING: Park County, along Beartooth Highway, under Populus tremuloides , 16 Aug 2014, EB0061-14 ( MONT).

Discussion.

Lactarius controversus is fairly easily recognized by its small basidiospores, whitish pileus, pinkish lamellae, acrid taste, and association with aspen. No other species is similar in the Rocky Mountains. While morphological differences between European and GYE material were not detected, there is some molecular divergence, which could indicate separate species, although more material needs to be examined (Figure 2B).