Lactarius tangerinus H. T. Le & De Crop 2015, sp. nov.
Creators: name: Wisitrassameewong, Komsit
name: Nuytinck, Jorinde
name: Le, Huyen Thanh
name: Crop, Eske De
name: Hampe, Felix
name: Verbeken, Annemieke
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Russulales
Russulaceae
Lactarius
Lactarius tangerinus

description: Lactarius tangerinus H.T. Le & De Crop, sp. nov. (Figure 10, 11e and 11f)   
 MycoBank number: MB811748; Facesoffungi number: FoF00641   
 Diagnosis: a small to medium sized species with reddish brown to reddish orange cap and a paler margin, watery latex, incompletely to almost completely reticulate basidiospores, pleuromacrocystidia present and pileipellis a trichoderm.   
 Etymology: —‘tangerinus’ refers to the reddish orange color on cap.   
 Typus: — THAILAND, Chiang Mai province, Mae Teang district, Pa Pae sub-district, Bahn Pha Deng village, mushroom research center, N19º17.12 E98º44.00, alt. 900 m, 28/07/2004, LTH 203 (holotype GENT!, isotype, CMU!, isotype, SFSU!).   
 Basidiocarps small to medium sized. Pileus 8−36 mm diam., plane to slightly infundibuliform with a central depression; surface rugulose, typically darker in center, reddish brown (8E8−F8) to dark brown (7F8), reddish blond (6C6), to beige, paler towards the margin, orange-yellow (4A3−5), light yellow (4A5) at the margin; margin striate at maturity. Lamellae 1.5−4 mm broad, decurrent with tooth, crowded, with 3−4 series of lamellulae, yellowish white (4A1−2) to light yellow (4A4) to grayish orange (5B5). Stipe 10−36 × 2−6 mm, cylindrical to tapering downwards, central to eccentric; surface dry, smooth, rugose when old, with paler color at apex, grayish orange (6B4) to pale orange (5A3) at apex, brownish orange (6C4), light brown (6D4), light brown (7D7−8), whitish pruinose at the base solid to hollow. Context 1−2 mm broad in the pileus, pale pinkish cream (5A3) to gray cream (5A− B3); odor like L. quietus or Pentatomidae bugs; taste mild. Latex transparent, abundant, unchanging on exposure, unchanging with 10 % KOH; taste mild. Macrochemical reaction on context: becoming pale grayish green with 10 % KOH, light grayish blue with FeSO 4.   
 Basidiospores subglobose to broadly ellipsoid, (5.8−)6.1− 6.6−7.2 −7.9 × 5.4− 6.1−6.3 −7.0 (−7.2) μm; Q = 1.02− 1.09−1.13 −1.25 (n=40); ornamentation amyloid, up to 1.8 μm high, composed of blunt to subacute, thick irregular ridges, forming an incomplete to almost complete reticulum; short ridges interconnected by fine lines; plage inamyloid to slightly amyloid. Basidia 30−65 × 9−18 μm, 4-spored, mostly subclavate, rarely subcylindrical, with fine granules and guttate contents. Pleuromacrocystidia not abundant, 35−77 × 10−18 μm, subcylindrical to subclavate, with mucronate apex, protruding up to 10 μm. Pleuropseudocystidia 2−4 μm broad, not protruding, tortuous to straight, cylindrical, with fine granules. Lamellar edge heterogeneous, consisting of basidia, subcylindrical to subclavate to obovoid marginal cells 15−30 × 4−15 μm, and a few cheilocystidia 39−49 × 11−15 μm, not protruding, subclavate, with mucronate apex. Lamellar trama composed of cylindrical hyphae, lactiferous hyphae and sphaerocysts. Pileipellis a trichoderm, about 35−50 μm thick, consisting of erect cylindrical hyphae, subpellis mainly with small globose cells, around 10−20 μm diam., intermixed with hyphae.   
 Habitat: solitary or gregarious on soil among leaf litter, near Lithocarpus thomsonii and L. elegon stands.   
 FIGRUE 10. L. tangerinus: a. basidiospore, b. pleuromacrocystidia, c. cheilocystidia, d. marginal cell, e. basidia, f. pseudocystidia, g. pileipellis (a− g: LTH203, holotype) (scale bar = 10 μm).   
 Collections examined: THAILAND, Chiang Mai province, Mae Teang district, Pa Pae sub-district, Bahn Pha Deng village, mushroom research center, N19º17.12 E98º44.00, alt. 900 m, 28/07/2004, LTH 203 (holotype GENT!, isotype, CMU!, isotype, SFSU!);— ibid., 13/08/2004, LTH217 (GENT!, CMU!, SFSU!);− ibid., 01/07/2011, KW091 (GENT!, MFLU!);— ibid., 28/07/2014, EDC14-475 (GENT!, MFLU!).   
 Comments: Immature basidiocarps of this species might be mistaken for L. fuscomaculatus or L. inconspicuus. However, L. fuscomaculatus has watery white latex and develops dark brown spots on the cap in mature specimens. The latex also separates L. tangerinus from L. inconspicuus. The latter species has watery white latex that slowly turns yellowish white or pale yellow. For the microscopic differences between both species, see under L. inconspicuus.
description: Published as part of Wisitrassameewong, Komsit, Nuytinck, Jorinde, Le, Huyen Thanh, Crop, Eske De, Hampe, Felix & Verbeken, Annemieke, 2015, Lactarius subgenus Russularia (Russulaceae) in South-East Asia: 3. new diversity in Thailand and Vietnam, pp. 215-241 in Phytotaxa 207 (3) on pages 235-236, DOI: 10.11646/phytotaxa.207.3.1, http://zenodo.org/record/13637261