Lactarius pseudodelicatus A.H. Sm.

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 : 26-28

Taxon classification Fungi Russulales Russulaceae

12. Lactarius pseudodelicatus A.H. Sm. Figure 14

Description.

Pileus 70-140 mm in diameter, broadly depressed–convex to broadly infundibuliform, viscid to dry, smooth to matted–tomentose especially near the margin, zonate to faintly zonate, yellow–buff to buff to pale orange–brown, lighter toward the margin; margin incurved and matted–tomentose to cottony–tomentose when young, remaining so or becoming straight and ± glabrous in age. Lamellae subdecurrent to decurrent, many of them branching, crowded, white to pale cream when young, becoming orange–buff to brown to gray–brown in age. Stipe 20-90 × 15-20 mm, tapering toward the base, smooth, white to pale buff, discoloring brown, often with scattered small scrobicules, hollow. Context firm. Latex copious, white, unchanging. Odor pleasant, fruity, of orange–citrus. Taste acrid.

Basidiospores 6-8 × 5-6.5 µm, Q = 1.2-1.5, broadly ellipsoid to ellipsoid; ornamentation forming a broken to partial reticulum. Pleuromacrocystidia 60-100 × 7-12 µm, numerous, strongly projecting, fusiform; apex acute. Cheilomacrocystidia 40-61 × 7-10 µm, numerous, strongly projecting, fusiform; apex acute.

Ecology and distribution.

Originally described from Michigan under aspen. There are very few subsequent reports. In the GYE, it is here reported with Populus tremuloides from the Teton Range of Idaho, summer.

Specimens examined.

U.S.A. IDAHO: Teton County, Teton, under Populus tremuloides , 27 July 1991, CLC233 (MONT), 24 Aug 1991, CLC296 (MONT), 26 July 1992, CLC512 (MONT).

Discussion.

This represents the first report of this species from the GYE under the name Lactarius pseudodelicatus . It was previously reported from the GYE as Lactarius cf. zonarius Fr. in Cripps and Miller (1993) and Cripps (2001). The European Lactarius zonarius has slightly larger basidiospores (6.3-9.2 × 5.1-7.4 µm), shorter pleuromacrocystidia (40-50 × 4-6 µm), and an ecology with Quercus ( Heilmann-Clausen et al. 1998).

Molecularly, Lactarius pseudodelicatus is very close to a specimen identified as Lactarius aff. wenquanensis Y. Wang & Z.X. Xie, from a humid montane rainforest with Quercus , Castanopsis , and Lithocarpus echinops Hjelmq. in Thailand (Figure 2B) ( Le et al. 2007). Lactarius aff. wenquanensis appears to be less robust with shorter pleuromacrocystidia (54-76 × 9.5-12 µm); it also appears to have a different ecology. Lactarius wenquanensis Y. Wang & Z.X. Xie, originally described from China has larger basidiospores (7.5-9.5 × (6 –)6.5– 7.5 µm) and the type was collected under Picea and Abies , as opposed to aspen ( Wang 2007). Lactarius torminosus (Schaeff.) Gray is closely related to Lactarius pseudodelicatus (Fig. 2B), however, Lactarius torminosus typically has smaller basidiomes, a more pink to brick pileus, slightly larger basidiospores (7.5-9.6 × 5.6-6.9 µm), and associates with Betula ( Heilmann-Clausen et al. 1998). Lactarius pubescens Fr. is also closely related to Lactarius pseudodelicatus (Figure 2B), and both associate with aspen in similar habitats. Lactarius pubescens is typically less robust and features a more pale pileus, a non-scrobiculate stipe, and smaller pleuromacrocystidia (30-60 × 6.5-10 µm) ( Heilmann-Clausen et al. 1998). Lactarius delicatus Burl., described from a deciduous forest in Eastern North America produces white latex that turns yellow ( Hesler and Smith 1979).