Lactarius pallidozonarius G.J. Li & W.F. Lin, sp. nov.
Index Fungorum number: IF 55864; MycoBank number: MB 55864; Facesoffungi number: FoF 09206; Fig. 1
Etymology – Refers to the pale zonary pileus.
Holotype – HBAU 15004
Basidiomata medium sized. Pileus 42–58 mm in diam., convex to hemispheric when young, then applanate to shallow
funneled, depressed at center when old, a pale erythrinus tinge of army brown (XL13′′′i), vinaceous fawn (XL13′′′b), fawn colour (XL13′′′) to light vinaceous-fawn (XL13′′′d) at center, fade to vinaceous buff (XL17′′′d), avellaneous (XL17′′′b) to pale vinaceous-fawn (XL13′′′f) towards the margin, densely zonate, dull, smooth, not viscid when wet; margin decurved first, expanded to partly curled upwards when mature, even, not striate, rarely cracked. Lamellae adnate to slightly decurrent, dense, 16–20 pieces per centimeter in the edge, interveined, rarely forked near stipe, 4–5 mm in height, white (LIII), turning a pale brownish tinge of yellow ocher (XV17′) to buckthorn brown (XV17′i) when injured, lamellulae numerous. Stipes 25–34×12–17 mm, central, cylindrical, tapered towards the base, white (LIII), turning a brownish tinge of tawny-olive (XXXIX17′′i) to isabella colour (XXX19′′i) when bruised, dull, smooth, not viscid when wet, first stuffed, partly cavernous when mature, annulus absent. Context 3–5 mm thick at the pileus center, White (LIII), same colour changes as the lamellae, taste mild, smell indistinct. Latex watery white, unchanging. Spore print cream to pale ocher.
Basidiospores [200/4/4] (6.2)6.5–8.1(–8.4)×4.8–6.0(–6.3) μm, Q = 1.01–1.30(1.34) μm, Q = 1.17 ± 0.08 μm), hyaline, subglobose to broad ellipsoid, rarely globose and ellipsoid, ornamentations amyloid, up to 1 μm in height, composed of incompletely to completely reticulated long ridges, isolated warts and short crests also exist, suprahilar area plage distinct and amyloid. Basidia 40–58×10–12 μm, hyaline, subcylindrical to clavate, four-spored, projecting 15–30 μm beyond hymenium, sterigmata 5–6 μm long. Hymenial cystidia not observed. Marginal cells 22–33×8–11 μm, subclavate to clavate, hyaline. Pseudocystidia abundant, aseptate, mostly embedded in subhymenium, rarely emergent, not brached, content granular; apex obtuse. Pileipellis a cutis, 100–300 μm thick, hyphae densely interwoven, rarely shriveled, 3–5 μm wide, hyaline, apex obtuse, rarely attenuated. Stipipellis an ixocutis, composed of interwoven, pale yellowish hyphae 3–5 μm wide.
Habit and habitat – scattered in broad-leaved forest of Salix spp. and Cinnamomum camphora. Material examined: CHINA, Zhejiang Province, Hangzhou City, Xihu District, Zhejiang University, Zijingang Campus, on ground, 28 June 2019, W.F. Lin, 20190016 (HBAU 15004, holotype); ibid, 20190701 (HBAU 15006); ibid, 26 June 2019, 20190005 (HBAU 15005); ibid, 20190753 (HBAU 15007).
GenBank numbers – ITS = MN658520, MN658521, MN658522, MN658523.
Notes – A new species, Lactarius pallidozonarius (Figs. 1 and 2) resembles L. inquinatus for their pale reddish brownish tinge near pileus center, lamellae turning reddish brown when injured, and watery white latex. Lactarius inquinatus however, has larger basidiospores 7.8–11 × 6.5–8.2 μm with lower ornamentations up to 0.5 μm in height, absence of hymenial pleurocystidia, and a habitat of forest dominated by Quercus (Lee et al. 2019). The other two closely related European species, L. evosmus and L. zonarius can be differentiated as following: L. evosmus has basidiocarps of fruity smell, and lower and less reticulated basidiospore ornamentations; L. zonarius has pale yellowish tinged pileus and subreticulate basidiospores (Heilmann-Clausen et al. 1998).
Figure 1 – Lactarius pallidozonarius (HBAU 15004, holotype). a Appearance of basidiomata on ground. b SEM photo of basidiospores. c Basidia. d Pseudocystidia. e Pileipellis. Scale bars: a=10 mm, c–e=10 µm
Figure 2 – Phylogram generated from maximum likelihood analysis based and ITS sequence data representing Lactarius pallidozonarius and closely related species. Related sequences are taken from Lee et al. (2019), UNITE and GenBank databases. Forty-nine sequences are included in the combined analysis which comprises 2505 characters 546 characters for ITS after alignment. Lactarius friabilis (GENT FH12-103), L. fuliginosus (GENT MTB97-24) and L. pterosporus (GENT DS09-614) in subg. Plinthogalus are used as the outgroup taxa. Tree topology of the maximum likelihood analysis is similar to the Bayesian analysis. The best RAxML tree with a final likelihood values of − 2161.573832 is presented. The matrix had 158 distinct alignment patterns, with 0.71% undetermined characters or gaps. Estimated base frequencies were as follows: A=0.229615, C=0.259476, G=0.226053, T=0.284855; substitution rates AC=0.965485, AG=9.458565, AT=0.865989, CG=0.392267, CT=8.367348, GT=1.000000; gamma distribution shape parameter α=0.217720. Bootstrap values for maximum likelihood (ML) greater than 50% and posterior probability values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian-inference analysis are shown above the nodes. Sequences of type specimens are presented in bold and newly generated sequences are in blue