New reports, phylogenetic analysis, and a key to Lactarius Pers. in the Greater Yellowstone Ecosystem informed by molecular data Author Barge, Edward G. Author Cripps, Cathy L. text MycoKeys 2016 15 1 58 http://dx.doi.org/10.3897/mycokeys.15.9587 journal article http://dx.doi.org/10.3897/mycokeys.15.9587 1314-4049-15-1 Taxon classification Fungi Russulales Russulaceae 15. Lactarius alnicola A.H. Sm. Figure 17 Description. Pileus 60-170 mm in diameter, depressed-convex to infundibuliform, glutinous when wet, with matted fibrils beneath the gluten especially near the margin, +/- faintly zonate, pale creamy yellow to pale yellow-brown to golden yellow-brown , discoloring orange-brown to brown where damaged; margin +/- faintly tomentose, incurved when young, becoming straight to wavy. Lamellae subdecurrent to decurrent, some forked toward the stipe, crowded, pale cream to pale buff, +/- slowly discoloring yellow and eventually orange-brown where damaged. Stipe 20-60 x 30-50 mm, equal to clavate to tapering toward the base, smooth, dry, conspicuously scrobiculate, white, discoloring orange-brown where damaged or in age, solid, becoming hollow. Context firm, white, +/- slowly discoloring yellow to orange-brown where damaged. Latex scarce to undetectable, white, +/- becoming very pale yellow, and slowly staining damaged tissue yellow. Odor mild to sweet. Taste quickly very acrid. Basidiospores 7.5-10 x 6-8.5 µm , Q = 1.2-1.5, broadly ellipsoid to ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 60-90 x 3-8 µm , rare, mostly near the pileus and between the lamellae, cylindric to fusiform; apex acute to moniliform. Cheilomacrocystidia absent. Ecology and distribution. In western North America and Mexico under conifers. Also reported from California with Quercus . In the GYE, Lactarius alnicola occurs in wet areas, often along streams in the spruce-fir zone, possibly always in the presence of Picea engelmannii , summer and early fall. Specimens examined. U.S.A. MONTANA: Gallatin County, Gallatin Range, Langhor Road, under Picea engelmannii , 27 Aug, EB0064-14 (MONT); Madison County, Tobacco Root Mountains, Branham Lakes, under Picea engelmannii , 1 Sept 2014, EB0067-14 (MONT). Discussion. Lactarius alnicola is phylogenetically very closely related to the European Lactarius scrobiculatus (Scop.) Fr., and may be conspecific, however more specimens need to be sequenced before making this determination final (Figure 2B). For morphological differences, Lactarius scrobiculatus features a heavily bearded pileus margin, and produces white latex which rapidly turns yellow ( Kytoevuori 1984 ). Lactarius alnicola , and other members of subsection Scrobiculati Hesler & A.H. Sm. sensu Kytoevuori (1984) form a strongly supported clade in the phylogeny (Figure 2B). Two varieties of Lactarius alnicola have been described: Lactarius alnicola v. pitkinensis Hesler & A.H. Sm., described from Colorado under aspen and conifers, has cream colored to white basidiomes, an acrid taste, unchanging latex, and unchanging (non-yellowing) flesh; Lactarius alnicola v. pungens Hesler & A.H. Sm., described from Michigan in mixed forest, has a dull ochraceous to ochraceous-tan , subviscid, glabrous pileus, an acrid taste, and white, unchanging latex, which stains white paper yellow ( Hesler and Smith 1979 ). Neither appear to fit the taxon described here. Figure 17. Lactarius alnicola . Top and bottom collection EB0064-14 under Picea engelmannii , Gallatin Range, Montana, USA. Scale bars: 2 cm. Photos by E. Barge.