Lactarius salicis-reticulatae Kuehner

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 : 16

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).