Lactarius fuscomaculatus Wisitrassameewong & Verbeken
MycoBank number: MB811743; Facesoffungi number: FoF00636
Basidiocarps medium sized. Pileus 25−62 mm diam., broadly convex initially, turning slightly infundibuliform to deeply infundibuliform in age, with a more or less distinct papilla; surface dry, more rugose in the center in age, brown (7D8 to 7E7) to dark brown (8F7) in the center, towards the margin, paler, brownish orange (5C5) to brown (6D7) to pale yellow (3A3), typically becoming uneven in color in age, with dark brown (8F7) discolorations, varying from spotted to brushed over the whole surface except the margin; margin indistinctly striate, slightly crenulate. Lamellae subdecurrent to decurrent, 1−3 mm broad, crowded, with 3−4 series of lamellulae, pale yellow (4A3) to cream-colored,
discoloring light brown (6D6) to brown (7E6), spotted in age. Stipe 34−76 x 4−7 mm, cylindrical, central, rarely slightly eccentric; surface dry, smooth, whitish pruinose, particularly in young specimens, dull yellow (3B3) to olive brown (4D6) at the apex, yellowish brown (5E4) to dark brown (7F5) towards the base, sometimes brownish orange (7C7), with 1−2 mm long hairs at the base. Context 0.5−4 mm broad in the pileus, partially hollow to completely hollow in stipe, pale yellow (3A3); odor strong, reminiscent of L. quietus or Pentatomidae bugs; taste mild. Latex watery white to white, abundant, unchanging on exposure, unchanging with 10% KOH, unchanging on white tissue paper and on white cotton handkerchief; taste slightly astringent and becoming faintly peppery. Macrochemical reaction no reaction on the context with 10% KOH, or with FeSO4. Basidiospores globose to broadly ellipsoid, 6.0−6.6−7.2−7.7(−7.8) × 5.5−6.1−6.6.−7.0(−7.2) μm, Q = 1.02−1.08−1.10−1.21 (n=100); ornamentation amyloid, composed of irregular ridges up to 1 μm high, forming an incomplete reticulum, warts and ridges connected by fine lines; isolated warts present; plage inamyloid to distally amyloid. Basidia42−53 × 13−17 μm, 4-spored, some 2-spored, subclavate to clavate; with guttate contents. Pleuromacrocystidia rare, protruding up to 10 μm, 55−68 × 13−17 μm, fusiform, with a mucronate, occasionally ramified apex. Pleuropseudocystidia scarce to abundant, 3−6 μm diam., not emergent to slightly emergent, cylindrical to tortuous with an obtuse apex, often broadened at the apex. Lamellar edge heterogeneous, composed of basidia, abundant cylindrical to subclavate, thinwalled marginal cells 13−26 × 5−13 μm; cheilocystidia absent to rare, 34−38 ×11−14 μm, not emergent, fusiform with a mucronate apex. Lamellar trama consisting of lactifers and sphaerocysts. Pileipellis a hyphoepithelium, with a thin upper layer of repent or oblique hyphae; suprapellis composed of cylindrical hyphae, 10−20 μm thick; subpellis a layer of large globose cells, up to 30 μm diam., mixed with cylindrical to inflated hyphae.
Habitat: gregarious to scattered on the ground in montane tropical forests with Fagaceae.
Collections examined: THAILAND, Chiang Rai province, Muang district, Thasai sub-district, forest near Doi Pui Reverse Signal Station, Doi Pui, N19º49.26 E99º52.19, alt. 655 m, 31/07/2012, KW373 (holotype, GENT!, isotype, MFLU!);−ibid., 25/07/2011, KW111 (GENT!, MFLU!);−ibid., 25/07/2011, KW112 (GENT!, MFLU!);−ibid., 01/09/2011, KW126 (GENT!, MFLU!);−ibid., 01/09/2011, KW128 (GENT!, MFLU!);−ibid., 01/09/2011, KW129 (GENT!, MFLU!);−ibid., 25/07/2012, KW370 (GENT!, MFLU!); Chiang Rai province, Mae Fah Luang district, Doi Mae Salong Nok sub-district, Doi Mae Salong, alt. 1269 m, N20°16.90 E99°62.30, 30/05/2012, KW221 (GENT!,MFLU!);−ibid., 30/05/2012, KW223 (GENT!, MFLU!); Chiang Rai province, Mae Fah Luang district, Doi Mae Salong Nok sub-district, Doi Mae Salong, N20º17.23 E99º61.69, alt. 1193 m, 22/07/2012, KW365 (GENT!, MFLU!);−ibid., 28/08/2013, KW466 (GENT!, MFLU!); Chiang Mai province, Mae-On district, Huaikaew sub-district, Bahn Pok M.1, N18º53.08 E99º21.45, alt. 1040 m, 02/06/2012, KW236 (GENT!, MFLU!); Chiang Mai province, Mae-On district, Huaikaew sub-district, Bahn Mae Kampong, N18º51.43 E99º22.09, alt. 1450 m, 03/06/2012, KW249 (GENT!,MFLU!).
Notes: Lactarius fuscomaculatus is widely distributed in tropical forests with Castanopsis and Quercus in Northern Thailand. The species can be confused with a closely related species, L. rubrobrunneus due to similarities in basidiocarps size, color, latex features and habitat. Both species are very similar in the immature stage, however, according to our experience, brown spots on the pileus are often found in fully mature fruiting bodies of L. fuscomaculatus, while L. rubrobrunneus is more unicolored. Under the microscope, both species have basidiospores with an incomplete reticulum and not many cystidia. A slight difference was observed in their pileipellis structures; L. rubrobrunneus has in part a very thin layer of repent hyphae which is like a transition between an epithelium and a hyphoepithelium, whereas L. fuscomaculatus has a more complete layer of repent hyphae covering the pileus. Lactarius fuscomaculatus may also be confused with L. tangerinus in the field. Lactarius tangerinus has smaller basidiomata, is typically paler in color without dark brown spots and possesses transparent latex. For more details on the difference between these two species, see under L. tangerinus.
Fig. 1 The obtained ML phylogeny based on ITS sequences. Names in boldface are new species. Names in blue are obtained from public databases. Bootstrap values and posterior probabilities are indicated if they exceed 50% and 0.85, respectively. The bar scale represents the expected number of nucleotide changes per site.