Lactarius indoviolaceus I. Bera & K. Das, 2022

Bera, Ishika, Das, Kanad & Datta, Bejoysekhar, 2022, A new species of Lactarius sect. Uvidi (Russulaceae) from India, Phytotaxa 576 (2), pp. 203-212 : 206

Lactarius indoviolaceus I. Bera & K. Das sp. nov. Figs. 2 , 3

MycoBank:—MB 844780

GenBank:— ON951745 (nrITS, Holotype) and ON951747 (nrITS)

Diagnosis:—A medium-sized Lactarius that can be separated from its closest relative, L. pyriodorus with its non-zonate, greyish yellow pileus and yellowish white stipe which turn pale violet on bruising or exposure of the context, much thinner pileipellis, and growth under Castanopsis spp .

Type:— INDIA. Arunachal Pradesh, West Kameng district: Shergaon , N 27°07.810’ E 092°15.116’, Elev. 2243 m, 22 July 2019, I. Bera & K. Das, IB 19-015 ( CAL 1876 , holotype!) .

Etymology:—The epithet refers to the basidiomata staining pale violet on bruising and occurring in India.

Description:— Pileus 65–75 mm diam., planoconvex with a deep central depression; surface moist, very greasy, finely and faintly rugulose in the centre, greyish yellow (4B3) at centre, lighter towards margin; margin regular, entire, smooth, incurved. Lamellae subdecurrent, close (10 L+l /cm at pilear margin), sometimes forked; lamellulae present, in 5 series; edge entire; yellowish grey (3–4B3), immediately turning pale violet (17A3) on bruising. Stipe 120–140 × 2–2.5 mm, central, cylindric with much broader base; surface viscid, finely rugulose, yellowish white (1–2A2) changing to pale violet on bruising, white mycelium present at the base. Context in pileus thin, pithy in stipe, yellowish white (1A2), almost immediately turning pale violet to greyish violet (17A–B3) on exposure, dull green (27E4) in KOH, brownish in guaiac and unchanging in FeSO 4. Latex moderate, watery white, turning cut lamellae pale violet. Taste very bitter. Odor pleasant. Spore print not obtained.

Basidiospores 6.0– 7.5 –9.5 × 5.0– 6.3 –8.0 μm, (n = 30, Q = 1.14– 1.26 –1.49), subglobose to ellipsoid; ornamentation amyloid, up to 0.8–1.1 µm high, composed of isolated or aligned warts and ridges to form an incomplete reticulum; suprahilar spot inamyloid. Basidia 44.2–59.0 × 11.7–12.5 µm, subclavate, 4-spored; sterigmata 4.0–5.0 × 1.2–1.4 µm. Pleuromacrocystidia abundant, 58.0–103 × 7.9–11.0 µm, emergent up to 40.3 µm, subcylindric with fusoid, subfusoid, mucronate, capitate, subcapitate to appendiculate apices, thin-walled; content dense, crystalline, needlelike. Pleuropseudocystidia scarce to abundant, up to 3 µm wide, emergent, cylindrical to slightly tortuous, with rounded apex. Lamellae edge fertile with basidia and basidioles. Cheilomacrocystidia not found. Subhymenium up to 10.5 µm thick, cellular. Hymenophoral trama composed of lactifers and nests of sphaerocytes connected with connecting hyphae. Pileipellis up to 173.5 µm thick, an ixocutis to ixotrichoderm composed of interwoven, septate, mostly ascending hyphae (8.6–29.2 × 2.0–3.0 μm) intermixed with lactiferous hyphae. Stipitipellis up to 70.2 μm thick, an ixocutis, composed of interwoven, septate hyphae (7.5–27 × 1.2–1.5 μm). Clamp connections absent in all tissues.

Habitat and distribution:—Growing solitary on soil in association with Castanopsis sp. in West Kameng district of Arunachal Pradesh.

Additional specimen examined:— INDIA. Arunachal Pradesh, West Kameng district: Shergaon , N 27°09.216’, E 092°16.174’, Elev. 2369 m, 26 July 2019, I. Bera & K. Das, IB 19-066 ( CAL 1877 ) .

Figures

FIGURE 2. Lactarius indoviolaceus (IB 19-015, holotype). a, b. Fresh basidiomata, c, d. Pale violet staining on the basidiomata, e. Macrochemical test on the context with i. KOH and ii. Guaiac, f & g. Transverse section through pileipellis, h–k. Transverse section through lamellae showing pleuromacrocystidia, l. Transverse section through stipitipellis. m, n. SEM micrograph of basidiospores. Scale bars: f−l= 10 μm, m, n= 2 μm. Photos by: Ishika Bera

FIGURE 3. Lactarius indoviolaceus (Line drawings from IB 19-015, holotype).a. Basidiomata, b. Basidiospores, c. Pleuromacrocystidia, d. Basidia, e. Pleuropseudocystidia, f. Pileipellis. Scale bars: b= 2 µm, c–f= 10 µm. Drawings by: Ishika Bera