Taxon classification Fungi Russulales Russulaceae

5. Lactarius salicis-reticulatae Kuehner Figure 7

Lactarius salicis-reticulatae The following morphological description is based on Barge et al. (2016).

Description.

Pileus 20-40 mm in diameter, convex to broadly convex, usually with a depressed center, smooth, viscid to dry, azonate, cream, pale yellow, or pale ocher, sometimes darker toward the center, staining violet where damaged; margin incurved, remaining so or becoming merely downturned in age. Lamellae adnate to subdecurrent, subdistant to distant, cream, pale yellow, or pale orange-ocher often with a pinkish-buff tint, staining violet where damaged. Stipe 15-20 × 10-15 mm, equal to clavate, viscid to dry, cream to pale-yellow, staining violet where damaged, hollow. Context white, staining violet where damaged. Latex scarce to undetectable, watery, white, becoming violet. Odor mild to slightly sweet. Taste mild.

Basidiospores (7 –)8.5– 11.5 × (7 –)8– 10 µm, Q = (1 –)1.1– 1.4, subglobose to ellipsoid; ornamentation forming an incomplete reticulum. Pleuromacrocystidia 76-101.5 × 7.5-11.5 µm, scarce, strongly projecting, subfusiform to fusiform; apex rounded to acute to moniliform. Cheilomacrocystidia 68.5-91.5 × 7.5-10.5 µm, scattered to abundant, strongly projecting, subfusiform to fusiform; apex acute to rounded to moniliform.

Ecology and distribution.

Widespread in arctic-alpine areas in the Northern Hemisphere with Salix . In the GYE, it occurs in alpine areas with Salix arctica, Salix reticulata, as well as shrubby Salix spp., sometimes also intermixed with Dryas octopetala, late summer.

Specimens examined.

U.S.A. MONTANA: Carbon County, Beartooth Plateau, Birch Site, among Salix reticulata, 17 Aug 2011, CLC2776 (MONT); Carbon County, Beartooth Plateau, Highline Trail, among dwarf Salix spp., 8 Aug 1998, CLC1211 (MONT); Carbon County, Hellroaring Plateau, Hellroaring Creek, under shrubby Salix sp., 8 Aug 2015, EB112-15 (MONT); among shrubby Salix sp. and Salix reticulata, 8 Aug 2015, EB113-15 (MONT); among Dryas octopetala, shrubby Salix sp. and Salix reticulata, 8 Aug 2015, EB117-15 (MONT), EB118-15 (MONT), EB119-15 (MONT); Sweet Grass County, Crazy Mountains, above Blue and Granite Lakes, among Salix arctica, 1 Aug 2015, EB101-15 (MONT). WYOMING: Park County, Beartooth Plateau, Gardner Lake, under shrubby Salix sp., 16 Aug 2014, EB0057-14 (MONT).

Discussion.

Lactarius aspideoides Burl., described from eastern North America is closely related (Figure 2A), however, it is generally larger, with a somewhat zonate pileus. It also has more crowded lamellae that lack salmon-colored hues, slightly smaller basidiospores (7-10 × 7 –8– µm) with broader ridges, a bitter to slightly acrid taste, and a subalpine ecology (Hesler and Smith 1979). The status of Lactarius aspideoides in western North America is unclear. Lactarius aspideus, another similar species which was described from northern Europe with Salix, has smaller basidiospores (6.7-9.5 × 5.6-7.8 µm) with denser reticulation, more crowded, creamier colored lamellae, and a habitat mainly in subalpine areas (Heilmann-Clausen et al. 1998). The presence of Lactarius aspideus in North America is unclear. Lactarius salicis-herbaceae Kühner, a closely related (Figure 2A) arctic-alpine Salix associate, which has not been reported from the Rocky Mountains, has darker yellow to yellow-brown sporocarps, pale cream to grayish buff lamellae, and more densely reticulate basidiospores (Heilmann-Clausen et al. 1998).