Lactarius montoyae
Lactarius montoyae Das K. & Sharma J.R.
Index Fungorum: IF488447
Pileus 12-66 mm diam., hemispherical when young, becoming plano-convex to infundibuliform when mature, often with subtle, radial pleats towards the margin, becoming more pronounced in older basidiomes; centre slightly depressed, sometimes with small papilla; surface dry, rugulose, greyish brown (5D4/5), browner when young. Lamellae adnate, sometimes with small decurrent tooth, subdistant to distant, rather broad (3-14 mm), with 3-4 series of lamellulae, dark cream-coloured; edge entire, concolourous. Stipe 23-80 × 3-8 mm, equal or slightly tapering downwards or upwards, often curved at the base, cylindrical, central to slightly eccentric; surface dry, smooth, concolourous with pileus or paler and greyer, especially at the apex and base. Context brittle, very thin-fleshy in pileus, 0.5-3.5 mm thick at mid-radius, spongy in stipe, white sometimes slowly becoming slightly yellowish white, pale yellowish with 10% KOH, turning pale grey (4C-D1) with FeSO4; smell fragrant; taste none to slightly sweet. Latex white, abundant; unchanging with 10% KOH. Spore print colour unknown. Basidiospores (6.4) 7.5–7.7–8.2–8.6 (9.7) × (6.2) 7.1–7.3–7.8–8.3 (8.8) μm (Q = 1.01–1.04–1.08–1.16; n = 120), globose to subglobose; ornamentation amyloid, winged, ridges firm and often somewhat irregular, < 2.5 μm high, slightly acute, mostly isolated and rather wide-spaced, sometimes branching but never reticulate; ridges often exhibiting a split appearance with often slightly crenulate edges; small warts present between the main ridges; plage distally to totally amyloid. Basidia 53-65 × 9-18 μm, subclavate to clavate, 4-spored, hyaline, thin-walled; sterigmata 3-10 × 1.5-2.5 μm. Pleuromacrocystidia absent. Pleuropseudocystidia 4-11 μm diam., scattered to moderately abundant, emergent or not, tortuous, sometimes branched, thin-walled. Lamellar edge sterile; cheiloleptocystidia 17-32 × 4-9 μm, subcylindrical or subfusiform, hyaline, thin-walled. Hymenophoral trama mixed, composed of hyphae interwoven with sphaerocysts; lactifers abundant. Pileipellis a palisade, 40-90 μm thick, containing intracellular, brown pigmentation in the upper layers; suprapellis composed of erect or recumbent terminal elements, 20-52 × 4-5 μm, long and slender, cylindrical or subfusiform, often septate, thin-walled; subpellis composed of few to several layers of inflated cells, 10-25 μm diam. Stipitipellis a trichoderm, 20-90 μm thick, containing brown, intracellular pigmentation in the upper layers.
Habitat and distribution: Solitary on the soil among leaves in midelevation rain forests dominated by Lithocarpus and Castanopsis. Reported from Northern India and Thailand.
Material Examined: THAILAND: Chiang Mai Province, Mae Teng Distr., Pang Sa Det, Mae Sae village, N19°14,59' E98°38.45', 962m alt., wet forest dominated by Pinus kesiya, Castanopsis armata and Lithocarpus sp., 25/08/2004, Huyen T. Le 218 (holotypus: CMU; isotypus: SFSU, GENT). – Chiang Mai Province, Mae Teng Distr., Ban Pha Deng village, near Pathummikaram Temple, along forest trail, N19°06.28,8' E98°44.47,3', 1050 m alt., rain forest dominated by Castanopsis armata, 07/06/2003, Huyen T. Le 42 (CMU, SFSU, GENT). – Chiang Mai Province, Doi Suthep-Pui National Park, Sangasahasri Lane to Huai Kok Ma village, N18° 48,62’ E098°54.60', 1146 m alt., primary montane forest with Castanopsis
armata, Castanopsis spp. and Lithocarpus polystachyus, 14/08/2003, Huyen T. Le 48 (CMU, SFSU, GENT) – ibid., 24/06/2005, leg. D.E. Desjardin, Huyen T. Le 296 (CMU, SFSU, GENT).– Chiang Mai Province, Mae Teng Distr., Ban Mae Sae village, dominated by Castanopsis armata and Pinus kesiya, 05/09/2004, Huyen T. Le 226 (CMU, SFSU, GENT) – Chiang Mai Province, Khun Chae National Park, 963 m alt., N19°04' E99°23', wet forest dominated by Castanopsis armata, Lithocarpus sp. and Pinus kesiya, 10/06/2005, Huyen T. Le 271 (CMU, SFSU, GENT).
Notes: Lactarius montoyae is a species described originally from Northern India (Kumaon Himalaya). It is recognized by its slender appearance, the rather distant and broad lamellae, a dry, greyish brown cap that in mature basidiomes often develops radial pleats towards the margin and is strikingly thin-fleshy, the mild taste, and the absence of a distinct colour change in the latex or context. Microscopically the main characters are the high, zebroid spore ornamentation (2.5 μm), the palisade structure in the pileipellis and a trichoderm in the stipitipellis. The type description differs slightly in mentioning a trichopalisade in both pilei- and stipitipellis. Since this could be explained by an either more or less pronounced layer of inflated cells, we still consider these descriptions consistent with each other. The ITS-inferred phylogeny places this species definitively in Lactarius subgenus Plinthogali, and completely supports the conspecificity of the Thai and Indian specimens. Other species with high, zebroid spore ornamentation that L. montoyae could be mistaken for are three species from Europe and North America: L. ruginosus Romagn., L. pterosporus Romagn. and L. subplinthogalus Coker. In contrast to L. montoyae, these three species exhibit a pink discoloration in the context and all three have an acrid taste. Furthermore, L. ruginosus can be distinguished by the moderately thick context, L. pterosporus by its crowded lamellae and wrinkled cap, and L. subplinthogalus by its paler and more yellowish colour and the hyaline and short, subcylindrical to broadly clavate terminal elements in the pileipellis.
Fig. 2 Lactarius montoyae. a. basidiomes, b. basidiospores, c. basidia, d. cheiloleptocystidia, e.
pleuropseudocystidia, g. pileipellis, h. stipitipellis. Scale bars = 10 mm (basidiomes) and 10
μm.
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