Lactarius indoevosmus Mehmood, Verma K., Uniyal & Sharma Y.P, 2022

Verma, Komal, Mehmood, Tahir, Uniyal, Priyanka & Sharma, Yash Pal, 2022, Lactarius indoevosmus and L. kanadii (Russulaceae), two new species from the northwestern Himalayas, India, inferred from morphology and molecular data, Phytotaxa 541 (2), pp. 165-177 : 167-172

Lactarius indoevosmus Mehmood, Verma K., Uniyal & Sharma Y.P sp. nov. 1 Figs. 3 , 4 .

MycoBank:—MB842103

GenBank:— OL687920 (holotype), OL688339 (Paratype)

Diagnosis:—Basidiomes with white to cream white, azonate pileus; white to cream white lamellae turning greyish orange to brown; large basidiospores (10.5–13.8 × 8.0–10.2 μm) with crests up to 0.75 μm high.

Etymology:—Refers to the morphological resemblance and close affinity with Lactarius evosmus .

Typification :— INDIA. Ladakh : Kargil district, Sankoo, 12 July 2021, 3117 m, N 34°24ʹ 33. E 76°44ʹ 47. 2, T . Mehmood , K. Verma & Y. P Sharma TMKVYPS 20-001 ( CAL 1867 , holotype) .

Description:— Pileus 55–120 mm diam., plano-convex to plane, initially depressed, becoming deeply infundibuliform; surface azonate, shiny, white to cream white (1A1–2A1), with light orange (5A4–5A5), yellowish beige (4B4) to brownish orange (5C5) hues, turning dark orange to greyish orange (5A7–5B6) after 20 to 40 minutes; margin entire, incurved to plane. Lamellae 2–4 mm broad, adnate to subdecurrent, rather crowded (10–12/cm including lamellulae), anastomosing, white to cream white (1A1–2A1), turning greyish orange (5B6) to brown (6D7), edges entire; lamellulae present in 4–5 lengths. Stipe 30–50 × 13–45 mm, central, cylindric, tapered towards base, dry, white to dull white, turning greyish orange (5B6) to brown (6D7). Context moderately thick at pileus, white, solid in stipe, turning greyish orange (5B6) on exposure; slightly yellowish brown (5D8) with 3 % KOH, deep red (10C8) with guaiac, olive green (1E3–4) with FeSO 4. Latex abundant, white, unchanging. Taste mild. Odour pleasant. Spore deposit not obtained.

Basidiospores 10.5–12.2–13.8 × 8.0–9.2–10.2 μm (n = 40, Q = 1.18–1.33–1.59); broadly ellipsoid to ellipsoid; ornamentation composed of irregular ridges up to 0.75 μm high and warts forming an incomplete reticulum; plage inamyloid. Basidia 54–68 × 12–14 μm, clavate to subclavate, hyaline, thin-walled, 4-spored; sterigmata 4–7 × 0.5– 0.8 μm. Pleurocystidia moderately abundant, 50–70 × 4–6.5 μm, emergent up to 11–15 μm, mostly embedded in the hymenium, subfusiform with moniliform to subobtuse apices. Lamellae edge sterile. Paracystidia 37–48 × 4–6 μm, subclavate. Cheilocystidia scarce, 35–54 × 3.0–5.0 μm, subfusiform, apex acute. Pseudocystidia moderate to abundant, 6–8 μm diam., emergent 10–15 μm, cylindric to tortuous, sometimes subobtuse at apex. Hymenophoral trama 30–50 μm thick, composed of lactifers and sphaerocytes. Pileipellis 180–260 μm thick, an ixocutis, composed of loosely interwoven, thin-walled, septate, repent hyphae 4–5 μm diam., under a very thin glutinous layer (6–10 μm), lactiferous hyphae abundant. Stipitipellis 60–105 μm thick, an ixocutis composed of interwoven, septate, thin-walled hyphae under a thin glutinous layer; hyphae 3–5 μm diam.

Habit and habitat: —Solitary to scattered, growing in associations with Salix alba and Prunus sp.

Additional specimens examined:— INDIA. Ladakh , Kargil, Sankoo, 3117 m elev., “ N 34°24ʹ 33. E 76°44ʹ 47. 2, 12 July 2021. T. Mehmood, K. Verma & Y. P Sharma, TMKVYPS 21-30, TM /KV/YPS 21-035, LK 21-06 .

Notes:—This species is placed in L. sect. Zonarii Quel. ( Heilmann-Clausen et al.1998) according to macro- and micromorphology. Morphologically and phylogenetically, Lactarius indoevosmus is close to the European species Lactarius evosmus (98 % identity for 98–100 % query coverage using BLAST) and Lactarius zonarius var. riparius . However, Lactarius evosmus can be differentiated by the pale cream to cream or pinkish buff, azonate pileus; whitish chrome to pale cream, decurrent lamellae; watery white, acrid latex; slightly smaller basidiospores (6.0‒9.2 × 4.6‒7.4 μm) with shorter (up to 0.5 μm high) ornamentation arranged in a zebra-like pattern, and scarce, never emergent pleuromacrocystidia ( Hesler & Smith 1979, Heilmann-Clausen et al.1998). Lactarius zonarius var. riparius is also close to Lactarius indoevosmus but the presence of tomentose to cottony–tomentose and glabrous pileus margin, nonforked lamellae, acrid taste and slightly smaller basidiospores 7–9 × 5.5–7.5 μm in Lactarius zonarius var. riparius separates it from Lactarius indoevosmus ( Barge and Cripps 2016) . Another Indian species of Lactarius reported from the same locality ( Lactarius drassinus ) could be confused in the field with Lactarius indoevosmus but the presence of a dull white to greyish brown, faintly zonate pileus; pinkish white lamellae; smaller basidiospores (8.0–11.5 × 5.5–8.0 μm) with ornamentation composed of ridges up to 0.8 μm high and warts forming an almost complete reticulum separates Lactarius drassinus from Lactarius indoevosmus ( Verma et al. 2021) . Lactarius indozonarius Uniyal, K. Das & Nuytinck (2018a: 471) , which was originally reported from India, differs from Lactarius indoevosmus by its viscid to glutinous, zonate pileus with hairy margin; scrobiculate stipe; fruity odour; subglobose to broadly ellipsoid basidiospores (7–8.5 × 6.5–7.5 µm) and association with Quercus leucotrichophora ( Uniyal et al. 2018a) .

Figures

FIGURE 3. Lactarius indoevosmus. a–e. Basidiomes in the field; f. Basidia; g. Cheilocystidia; h. Pleurocystidia; i. Pseudocystidia; j. Paracystidia; k,l. Transverse section through pileipellis; m. Basidiospores under light microscope; n–p. Basidiospores under SEM. Scale bars: a–c = 20 mm, f–m = 10 μm. n,o = 2 μm, p = 5 μm. Photos a–e by Y. P Sharma and f–l by Komal Verma.

FIGURE 4. Lactarius indoevosmus. a. Basidia; b. Basidiospores; c. Cheilocystidia d. Pseudocystidia; e. Pleurocystidia; f. Paracystidia; g. Pileipellis. Scale bars: a, c–f = 10 μm, b = 2 μm. Drawings by Tahir Mehmood.