Lactarius flaviaquosus X. H. Wang 2019, sp. nov.
Creators: name: Wang, Xiang-Hua
name: Das, Kanad
name: Bera, Ishika
name: Chen, Yu-Hui
name: Bhatt, Rajendra Prasad
name: Ghosh, Aniket
name: Hembrom, Manoj Emanuel
name: Hofstetter, Valérie
name: Parihar, Arvind
name: Vizzini, Alfredo
name: Xu, Tai-Min
name: Zhao, Chang-Lin
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Russulales
Russulaceae
Lactarius
Lactarius flaviaquosus

description: 86. Lactarius flaviaquosus X.H. Wang, sp. nov.
(Figs 9; 10D; 14)
A medium-sized species with faintly zonate pileus, latex yellow or white changing to yellow and watery instantly, rarely white or watery, ellipsoid spores with isolated conical warts and pileipellis an (ixo-)lattice
TYPUS. — China. Yunnan Prov., Maguan Co., Dalishu, Adushangba, 27°03’3.28’’N, 104°08’18.52’’E, 1800 m a.s.l., in fagaceous forest, 13.X.2017, coll. X.H. Wang, no. 4734 (holo-, KUN [HKAS 104207]!).
MYCOBANK. — MB 829289.
GENBANK. — MK351937 - MK351941 (ITS).
ETYMOLOGY. — Flavi- = yellow, -aquosus = water, referring to the yellow latex or white then changing to yellow and watery.
ADDITIONAL SPECIMENS EXAMINED. — China. Yunnan Prov.: Baoshan, Gaoligong Mts. nature reserve, old road from Baoshan to Tengchong, 20 km to Bawan, 17.VII.2003, coll. X.H. Wang, no. 1553 (KUN[HKAS 43947]); Lüchun Co., Huanglian Mt. nature reserve, near Huanglianshan reservoir, 8.VII.2012, coll. X.H. Wang, no. 3523 (KUN[HKAS 76060]); Maguan Co., Gulinqing, 2000 m a.s.l., 29.VI.1992, coll. Z.L. Yang, no. 1821 (KUN[HKAS 25946]); Malipo Co., Laojun Mt. nature reserve, 1500 m a.s.l., 23.VI.1992, coll. Z.L. Yang, no. 1763 (KUN[HKAS 25950]); ibid, 24.VI.1992, coll. Z.L. Yang, no. 1794 (KUN[HKAS 25951]); Pingbian Co., Dawei Mt. nature reserve, 1800-2100 m a.s.l., 4.VII.1992, coll. Z.L. Yang, no. 1877 (KUN[HKAS 25947]); ibid, 4.VII.1992, coll. P.G. Liu, no. 1280 (KUN[HKAS 25948]); Pingbian Co., near the county town, 1500 m a.s.l., 21.VII.2005, coll. X.H. Wang, no. 1934 (KUN[HKAS 49562]); Zhenyuan Co., 313 provincial road (from Zhenyuan to Mengda), 4.VII.2012, coll. X.H. Wang, no. 3431 (KUN[HKAS 75992]). — Taiwan Prov.: Ilan Co., Fushan Botanical Garden, 600 m a.s.l., 20.IV.1993, coll. W.N. Chou, no. CWN-TF615 (TNM[F0023042]); Nantou Co., Hsinyi, Tachieshan, 13.IV.1995, coll. W.N. Chou, no. CWN00783 (TNM[F0003237]); Nantou Co., Yuchih Hsiang, Lienhuachih, 22.IV.2006, coll. W.N. Chou, no. CWN07078 (TNM[F0027273]).
HABIT, HABITAT AND DISTRIBUTION. — 1-4 individuals growing together, in fagaceous forest. Southwestern (Yunnan Prov.) and southeastern (Taiwan and Zhejiang Provinces) China (Gao et al. 2013; GenBank accession JQ991751).
DESCRIPTION
Basidiomata
Small to medium-sized.
Pileus
20-50 mm in diam., depressed with an expanded margin, with age often translucently striate at margin; surface smooth, slightly viscid when wet, yellowish brown, reddish brown, brownish orange, darker at center, faintly zonate.
Context
1 mm thick, pale brown.
Lamellae
2-3 mm broad, straight to short decurrent, crowded, concolorous with pileus.
Stipe
20-70 × 3-7 (10) mm, cylindrical, equal, solid then hollow; surface smooth, dry, concolorous with pileus or with more reddish tinge, light brown, often strigose at the base.
Latex
Yellow or white changing to yellow watery instantly, rarely white or watery and unchanging, acrid, sharp.
Spore print
not obtained.
Basidiospores
(340/17/10) (6.0) 6.5-7.4-8.5 (9.5) × (5.0) 5.5-5.9-6.5 (7.5) Μm [Q = (1.09) 1.17-1.36 (1.43), Q = 1.26 ± 0.06] [holotype (40/2/1) (6.5) 7.0-7.4-8.0 (8.5) × (5.0) 5.5-5.8- 6.5 Μm, Q = (1.17) 1.21-1.38 (1.43), Q = 1.28 ± 0.06], ellipsoid, rarely broadly ellipsoid; ornamentation 0.6-1.3 (1.5) Μm high, of isolated conical warts, few of them fused or connected by fine lines; plage distally amyloid or inamyloid.
Basidia
4-spored, 30-45 × 8-13 Μm, clavate.
Pleuromacrocystidia
Uncommon to numerous, emergent, projecting up to 30 Μm beyond the basidia layer, originating from subhymenium or hymenophoral trama, (40) 50-100 (120) × 7-12 (15) Μm, subfusiform, sublanceolate, rarely subcylindrical, with a sharp apex, with dense yellowish granular or crystalline contents.
Lamella edge
Fertile with few basidia; cheilomacrocystidia common to numerous, 20-60 × 5-9 Μm, fusiform, subcylindrical, apex often moniliform or with apical appendices, with strongly refractive granular, crystalline or agglomerated contents; marginal cells 7-30 × 4-10 Μm, clavate, cylindrical.
Hymenophoral pseudocystidia
Rare to common, 2-3 Μm broad, rarely forking, with refractive contents.
Pileipellis
An (ixo)cutis or (ixo)lattice, 50-170 Μm thick; hyphae (3) 4-10 (12) Μm broad, terminal cells 15-65 × 3-6 Μm, with a blunt apex, some shrivelled, hyphae in subpellis gelatinized, colorless to pale yellow, some slightly thick-walled (0.5 Μm).
Stipitipellis
A cutis, 30-60 Μm thick; hyphae closely packed, 3-6 Μm broad, with a blunt apex, gelatinized, slightly thick-walled, nearly colorless.
Lactifers
Numerous, in hymenophoral trama nearly colorless to pale yellowish brown, in pileus and stipe trama robust, pale to golden yellowish brown.
Pileus and stipe trama
With numerous rosettes.
NOTES
The holotype has white milk that changed yellow instantly, whereas ZLY1763, 1794, 1821, 1877 and XHW3431 have yellow milk. The milk of XHW3525 is watery and unchanging. The holotype, XHW3431, and XHW3525 are sequenced and they have nearly identical ITS sequences (Fig. 9). As the latex of this species seems variable, three specimens with the same microscopical characters but whitish milk (XHW1553, XHW1934 and PGL1280) are here also identified to belong to the same species. The ellipsoid spores with isolated warts and the pileipellis an ixocutis-lattice with inflated hyphae are good specific characters. Indian L. atrii seems to be similar, but has bigger spores with blunt warts and azonate pileus. Thai L. aquosus H.T. Le & K.D. Hyde, a species showing affinity to this new species in the ITS phylogeny, has unchanging watery latex, reticulate spores and much broader hyphae in the pileipellis (Wisitrassameewong et al. 2015). Two species of L. subg. Russularia with yellowing latex are reported from subalpine southwestern China (Wisitrassameewong et al. 2016). They both have azonate pileus and more connected spore ornamenta - tion. For notes on species with isolated warts, see under L. collybioides.
description: Published as part of Wang, Xiang-Hua, Das, Kanad, Bera, Ishika, Chen, Yu-Hui, Bhatt, Rajendra Prasad, Ghosh, Aniket, Hembrom, Manoj Emanuel, Hofstetter, Valérie, Parihar, Arvind, Vizzini, Alfredo, Xu, Tai-Min & Zhao, Chang-Lin, 2019, Fungal Biodiversity Profiles 81 - 90, pp. 57-95 in Cryptogamie, Mycologie 20 (5) on pages 76-77, DOI: 10.5252/cryptogamie-mycologie2019v40a5, http://zenodo.org/record/7814899