Lactarius aff. olivinus 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 : 34-35

Taxon classification Fungi Russulales Russulaceae

17. Lactarius aff. olivinus Kytoev. Figure 19

Description.

Pileus 30-110 mm in diameter, depressed–convex to infundibuliform, viscid when wet, with appressed, agglutinated scales of confluent hairs, especially near the margin, more or less azonate, cream to olive–buff to yellow–tan to orange–tan, ± darker toward the center; margin incurved and wooly–tomentose when young, often forming a cottony rim, becoming straight and more or less glabrous. Lamellae subdecurrent, crowded, cream, staining yellow where damaged and then fading or eventually becoming pale ochraceous. Stipe 30-45 × 10-25 mm, equal to clavate to tapering toward the base, smooth, dry, cream to pale yellow–tan to orange–tan, ± with pale yellow–tan scrobicules, often with a white ring near the apex, solid, becoming hollow. Context white, staining pale yellow at first and then fading. Latex scarce to undetectable, white, becoming yellow, staining tissue yellow and then fading. Odor faintly sweet to faintly spermatic. Taste mild.

Basidiospores 7.5-10 × 5.5-7 µm, Q = 1.3-1.5, ellipsoid; ornamentation forming a partial reticulum. Pleuromacrocystidia 51-100 × 9-14 µm, abundant, strongly projecting, fusiform to lanceolate; apex acute to moniliform. Cheilomacrocystidia absent.

Ecology and distribution.

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

Specimens examined.

U.S.A. MONTANA: Park County, Silver Gate, under Picea engelmannii , 13 Aug 2014, EB0050-14 (MONT), EB0051-14 (MONT).

Discussion.

This species is morphologically close to the European Lactarius olivinus except for the mild rather than acrid taste. Molecularly (Figure 2B), and ecologically, it is also close, however we refrain from calling it that species until more collections are examined and compared with European material. It is also very close to some interpretations of the North American taxa Lactarius scrobiculatus v. canadensis , and Lactarius gossypinus , except it has larger basidiospores and pleuromacrocystidia. Lactarius payettensis is also similar, but it has unchanging latex, and a strongly acrid taste. See comments under Lactarius aff. tuomikoskii for additional information.