Lactarius swaticus Sana & Kiran, 2025

Kiran, Munazza, 2025, Morpho-anatomical and nrITS based identification of Lactarius swaticus (Russulaceae, Russulales) from Pakistan: An addition to the global mycoflora, Phytotaxa 690 (1), pp. 47-62 : 54-56

Lactarius swaticus Sana & Kiran , sp. nov. ( Figs. 2 & 3 )

MycoBank:—MB855658

Etymology:—The specific epithet “ swaticus ” refers to the type locality Swat, Pakistan.

Diagnosis:— Lactarius swaticus is characterized by yellow-orange to orange colored basidiomata, planoconvex, umbilicate pileus with smooth crenate margins, ventricose lamellae, globose to broadly ellipsoid, partial to nearly complete reticulated basidiospores, narrowly clavate to clavate marginal cells, an irregular trichoderm pileipellis and absence of leptocystidia and pleuromacrocystidia.

Holotype:— PAKISTAN. Khyber Pakhtunkhwa, Swat District, Aligrama Village , 34.80068° N, 72.31424° E, 908 m a.s.l. on soil under Quercus spp. , 30 July 2023, Wajid Ali, AS-5 (LAH38286!; ITS: PQ249118).

Habit and Habitat: On soil under Quercus spp. in Aligrama Village, Swat, Pakistan.

Description:—Pileus 32–47 mm broad, initially planoconvex, becoming umbilicate at maturity, surface smooth and dry, margins smooth, initially undulate becoming crenate at maturity, yellow-orange (7.5 YR 8/8; 7.5 YR 7/8) to orange (7.5Y YR 6/8) in color. Lamellae 1–2 mm broad with even entire margins, ventricose, adnexed, crowded, concolorous with pileus. Lamellulae 0.5–1.5 mm broad with entire margin, concolorous with pileus. Stipe 50–85 mm × 15–17 mm, central, equal and cylindrical, hairs present on surface, concolorous with pileus.

Basidiospores [40/2/2], (4.69–)4.84–7.28(–7.63) × (3.55–)4.30–6.48(–6.76) μm, [avL × avW 6.11 × 5.35 μm, Q= 1.02–1.27, Q av =1.13], globose to broadly ellipsoid, amyloid ornamentation up to 1.1 μm high, consisting of warts and ridges, forming partial to nearly complete reticulum. Basidia (31.70–)32.11–37.44(–39.09) × (9.69–)10.02– 12.24(–12.96) μm, narrowly clavate to broadly clavate. Basidioles (25.12–)27.02–32.11(–35.23) × (7.06–)8.23– 10.01(–11.29) μm, abundant, narrowly clavate to broadly clavate. Pleuromacrocystidia absent. Cheilomacrocystidia (32.23–)34.11–38.43(–40.01) × (11.06–)12.00–14.09(–16.46) μm, clavate to broadly clavate. Pleuroleptocystidia and cheiloleptocystidia absent. Marginal cells common, 9.54–11.88 μm long, narrowly clavate. Pileipellis an irregular trichoderm, hyphae septate, 2.87–4.62 μm diam. (avW = 3.60 μm), with subclavate to clavate apex. Pileus trama contain sphaerocysts measuring (16.01–)20.08–33.11(–38.77) × (15.12)18.28–26.09(–30.04) μm, globose to subglobose. Stipitipellis cutis, hypha septate, 3.09–4.84 μm diam. (avW = 4.01 μm). The stipe trama consists of parallel cylindrical elements measuring 11.5 –17.52 μm diam. (avW = 15.29 μm, rounded at apex and lactiferous hyphae measuring 3.67–4.71 diam. (avW = 4.19 μm), which exhibit a characteristics yellow coloration. Caulocystidia not found.

Additional material examined: PAKISTAN. Khyber Pakhtunkhwa, Swat District, Aligrama Village, 34.80068° N,

72.31424° E, 908 m a.s.l. on soil under Quercus spp. , 31 July 2023, Wajid Ali, A5 (LAH38287!; ITS: PQ249117).

Figures

FIGURE 2. A–D. Basidiomata of Lactarius swaticus. A–B. Basidiomata (Holotype, LAH38286), C–D. Basidiomata (Paratype, LAH38287). Scale bars A–D= 10 mm.

FIGURE 3. A–K. Microscopic structures of Lactarius swaticus (Holotype, LAH38286). A–B. Scanning micrographs of basidiospores. C. Basidiospores in Melzer ‘s reagent, D. Basidia, E–F. Cheilomacrocystidia, G. Marginal cells, H. Lactiferous hyphae in stipitipellis, I. Transverse section of pileipellis, J. Sphaerocysts in pileus trama, K. Elongated cells in stipe trama. Scale bars: C = 10 μm, D = 9 μm, E–F = 15 μm, G = 27 μm, H, I = 22 μm, J = 20 μm, K = 26 μm.