Name: Lactarius formosus H.T. Le & Verbeken
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First person to use this name on MO: Danny Newman
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Rank: Species

Status: Accepted

Name: Lactarius formosus

Author: H.T. Le & Verbeken



Domain: Eukarya

Kingdom: Fungi

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Russulales

Family: Russulaceae

Genus: Lactarius

Brief Description:

Pileus 27 mm diam., plano-convex with slight central depression and a very small papilla; surface viscid, zonate, scaly, covered with bundles of glutinous hairs, greyish yellow to yellowish buff with some olivaceous tones, changing quickly to dark purple (14F4) when bruised or broken; margin hairy. Lamellae subdecurrent, close to crowded, up to 1 mm broad, with 3 series of lamellulae, yellowish white (4A2), becoming dark ruby (12F4) when bruised or broken; edge dark purple (14F5). Stipe 40 × 6 mm, tapering upwards, central, greasy to dry, scrobiculate, yellowish white (4A2) at apex, concolourous with pileus, quickly changing to dark purple (14EF5) when bruised. Context 2.5 mm thick in pileus, greyish white to purplish white (14A2), hollow in stipe, pale yellow (3A3) with KOH 10%, dull yellow (3B3) with FeSO4; smell distinct; taste mild. Latex cream to yellowish white (4A2), staining the lamellae dark purple, pale yellow (3A3) to brownish orange (5C4) with KOH 10%. Spore deposit unknown.
Basidiospores 8–9.7–11.3 (11.6) × 7.4–8.8–10.1 μm, (n = 20, Q = 1.01– 1.1–1.38), globose to ellipsoid; ornamentation up to 0.6 (–1.6) μm high, composed of rather broad ridges, forming a mostly complete reticulum; plage inamyloid. Basidia abundant, 48–77 × 13–18 μm, with sterigmata 2–7 μm long, 4-spored, hyaline, sometimes with granular and guttate contents, thin- walled, subclavate. Pleuromacrocystidia abundant, 35–90 × 8–13 μm, emergent, subfusiform, with a mucronate to moliniform apex, hyaline or with granular contents, thin-walled. Pleuropseudocystidia not abundant, 8–11 μm wide, emergent up to 30 μm, tortuous to cylindrical, with lactiferous contents, thin-walled. Hymenophoral trama composed of filamentous hyphae. Lamellae edge sterile; marginal cells 11–21 × 3.5–7 μm, abundant, hyaline, 1-septate, cylindrical, thin-walled; cheilocystidia 29–60 × 8–9 μm, hyaline, subfusiform, similar to pleuromacrocystidia but smaller, with mucronate to moliniform apex. Pileipellis a cutis to a trichoderm, 120–140 μm thick; underlying layer composed of thin-walled filamentous hyphae and sphaerocytes. Stipitipellis a trichoderm, 90–130 μm thick composed of thin-walled hyphae; underlying layer composed of sphaerocytes and filamentous thin-walled hyphae.
Habitat and distribution: solitary in the soil among leaves near Pinus kesiya and Castanopsis armata.
Material examined: THAILAND, Chiang Mai Prov., Mae Taeng Dist., Tung Joaw village, N19°08.07’ E098°38.09’, 1423 m alt., rainforest dominated by Castanopsis armata and Pinus kesiya, 16 October 2005, leg. Huyen T. Le 382 (holotype CMU; isotype GENT, SFSU).

Discussion: The species is striking in the field because of the quick colour change to violet in all parts combined with a hairy, viscid, zonate pileus and a scrobiculate stipe.

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Created: 2016-04-07 23:24:18 CDT (-0500) by Danny Newman (myxomop)
Last modified: 2018-12-28 00:14:54 CST (-0600) by Image Sharer (image sharer)
Viewed: 14 times, last viewed: 2019-09-29 18:28:02 CDT (-0500)
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