Lactarius aff. tuomikoskii Kytoev .

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 : 32-34

Taxon classification Fungi Russulales Russulaceae

16. Lactarius aff. tuomikoskii Kytoev. Figure 18

Description.

Pileus to 80 mm in diameter, broadly convex with a depressed center, glutinous when wet, with matted fibrils beneath the gluten especially near the margin, azonate, pale yellow–cream to yellow–tan, discoloring brown in places; margin densely bearded, incurved at least when young. Lamellae subdecurrent, crowded, cream to pale yellow–cream, ± discoloring yellow and eventually rusty brown where damaged. Stipe 30 × 20 mm, tapering toward the base, smooth, dry, white to pale yellow–tan, with small, faint, dull yellow–tan scrobicules, hollow. Context white, ± slowly discoloring pale yellow to faintly tan where damaged. Latex scarce, white, becoming very pale yellow, and slowly staining damaged tissue pale yellow. Odor sweet. Taste acrid.

Basidiospores 7-10 × 5.5-7.5 µm, Q = 1.2-1.5, broadly ellipsoid to ellipsoid; ornamentation forming a broken to nearly complete reticulum. Pleuromacrocystidia 50-100 × 7-12 µm, abundant, strongly projecting, fusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia absent.

Ecology and distribution.

In montane, rich, moist habitats with Picea engelmannii , late summer.

Specimens examined.

U.S.A. MONTANA: Park County, Silver Gate, under Picea engelmannii , 13 Aug 2014, EB0052-14 ( MONT).

Discussion.

This species, along with Lactarius alnicola , and Lactarius aff. olivinus Kytöv. described below, fall in subsection Scrobiculati as recognized by Kytövuori (1984). Morphologically, it is quite close to the European Lactarius tuomikoskii Kytöv. It is also very close to some interpretations of Lactarius scrobiculatus v. canadensis A.H. Sm., and Lactarius gossypinus Hesler & A.H. Sm., except it has larger basidiospores and pleuromacrocystidia. Lactarius payettensis A.H. Sm. is also similar, but differs by having a more robust, heavily scrobiculate stipe and apparently unchanging latex ( Hesler and Smith 1979). Both Lactarius gossypinus and Lactarius payettensis have been previously reported from the GYE ( McKnight 1982), however neither were examined for this treatment. Overall, the complex of species surrounding Lactarius scrobiculatus in North America, which includes Lactarius alnicola , Lactarius gossypinus , Lactarius payettensis , Lactarius scrobiculatus v. canadensis , Lactarius scrobiculatus v. montanus Methven, and the two taxa described here ( Lactarius aff. tuomikoskii , and Lactarius aff. olivinus ) appears to be in need of revision, especially in relation to European taxa such as Lactarius auriolla Kytöv., Lactarius leonis Kytöv., Lactarius olivinus , Lactarius scrobiculatus , and Lactarius tuomikoskii ( Kytövuori 1984).