Lactifluus khasianus D. Chakr., A. Ghosh & D. Tudu, 2025

Lactifluus khasianus D. Chakr., A. Ghosh & D. Tudu , sp. nov. Figs. 2 View FIGURE 2 & 3 View FIGURE 3

MycoBank: MB 859374

GenBank: PV688192 (nrITS, holotype), PV688193 (nrITS); PV688191 (nrLSU, holotype), PV688194 (nrLSU).

Etymology:—Specific epithet ‘ khasianus ’ refers to the type locality, Khasi Hills, India.

Diagnosis:— Lactifluus khasianus differs from other species of Lf. sect. Gerardii by the chocolate brown coloured pileus, slightly larger cheilomacrocystidia and differences in the nuc. rDNA ITS and LSU sequence data.

Holotype:— INDIA. Meghalaya: East Khasi Hills district, Kseh Pomaaro , N 25°22’51.7’’ E 91°35’52.8’’, Alt. 1646 m, 29 September 2024, D. Chakraborty & D. Tudu, ML 24-116 ( ASSAM F019 , holotype!). GoogleMaps

Description:— Pileus 20–110 mm in diam., convex to plano-convex with depressed centre; centre with a small umbo; margin crenate, incurved when young, becoming decurved to plane with maturity; surface dry, smooth when young, becoming radially rugulose to rugose towards margin at maturity, sometimes areolate at several places on the cap surface showing the context, velutinous with a faint sheen, dark brown to chocolate brown (7–8E5–7), becoming paler in older specimens. Lamellae decurrent, subdistant (5–6/ cm at pileus margin), rather thick and broad ( 5–20 mm), somewhat waxy, pale cream (3–4A2); edges entire and concolorous; lamellulae present in 3–4 series. Stipe 25–55 × 6–13 mm, more or less cylindrical and equal, often slightly curved; surface dry, faintly longitudinally striate near apex, velutinous, concolorous with pileus or coffee to raw umber or darker at the apex (5F7– 8, 6E 5) and pale brown to yellowish brown downwards (5D5, 5–6E5), sometimes whitish due to spore deposition on the surface, basal mycelium white, unchanging after bruising or on exposure; turning orange (5A6–7) with FeSO 4 and negative with KOH. Latex moderately abundant, white (1A1), unchanging on cut lamellae. Taste not distinctive. Smell pleasant. Spore print white (1A1).

Basidiospores (40/2/2) 7.7– 8.9 –10.2 × 7.0– 7.8 –9.3 μm, [Q=1.01– 1.06 –1.10]subglobose to globose; ornamentation amyloid, composed of obtuse-rounded, conical amyloid warts (0.4–0.7 μm high), connected by thick ridges forming a complete network, sometimes intermingled with very few isolated warts; suprahilar plage inamyloid; apiculi up to 1.8 μm high. Basidia 54–71 × 7–10 μm, narrowly clavate, mostly 4-spored, sometimes 2-spored, with some guttate contents; sterigmata 5–7 × 1–2 μm. Pleuromacrocystidia rare, 45–52 × 7–8 μm, narrowly ventricose or fusiform with rounded-obtuse apex; content granular. Pleuropseudocystidia moderately scarce, smooth, cylindrical with obtuse apex or somewhat tapering; content dense with few refringent particles. Lamellae edge sterile with basidioles and cystidia. Cheilomacrocystidia abundant, 25–45 × 5–8 μm, subcylindrical or broadly clavate with mostly rounded apex, occasionally septate, arising from inflated basal cells. Subhymenium layer up to 20 μm thick, cellular, pseudoparenchymatous. Hymenophoral trama almost cellular; lactifers moderately abundant. Pileipellis a palisade, 60–100 μm thick, thin walled; upper layers containing intracellular brown pigmentation; suprapellis composed of erect and oblique terminal elements, 8–30 × 4–8 μm, mostly sub-cylindrical, sometimes subclavate or broadly conical with fusoid apex, sometimes 2-celled; subpellis composed of 2–4 layers of subglobose to broadly ellipsoid cells (15–20 × 9–17 μm), underlying layer composed of densely packed, parallel hyphae. Stipitipellis a palisade, 40–50 μm thick, more or less similar to pileipellis except with longer terminal elements (15–35 × 5–11 μm) of suprapellis; subpellis 2–3 cell layers. Clamp connections absent in all tissues.

Habitat:—Solitary to scattered, growing in ectomycorrhizal association with Pinus kesiya ( Pinaceae ) in temperate mixed forests.

Additional specimen examined:— INDIA. Meghalaya: East Khasi Hills district, Per Meiru, N 25°22’46.4’’ E 91°35’54.2’’, Alt. 1640 m, 29 September 2024, D. Chakraborty & D. Tudu, ML 24-120 ( ASSAM F020).