Lactarius drassinus Verma K., Uniyal, Sharma Y.P & Mehmood, 2021

Verma, Komal, Mehmood, Tahir, Uniyal, Priyanka, Kapoor, Rupam & Sharma, Yash Pal, 2021, Two new species of genus Lactarius (Russulaceae) from North-western Himalaya, India, Phytotaxa 500 (4), pp. 253-265 : 260-263

Lactarius drassinus Verma K., Uniyal, Sharma Y.P & Mehmood , sp. nov. Figs. 5 , 6

MycoBank:—MB838922.

GenBank:— MW581848 , MW595906 , MW624687 .

Diagnosis:—Distinct from Lactarius controversus by the combination of the following characters: dull white to greyish brown pileus, decurrent to subdecurrent lamellae; copious, white latex; mild taste; broadly ellipsoid to elongate basidiospores (8.0–11.5 × 5.5–8.0 μm) with a complete reticulum type as ornamentation composed of ridges (0.8 μm high); moderate to abundant pleuromacrocystidia (54–74 × 5–7.5 μm) mostly embedded in the hymenium layer; very few cheilocystidia.

Etymology:—“ drassinus ” (Lat.) refers to the type locality Drass, Ladakh, India.

Typification :— INDIA. Ladakh : Kargil district, Drass, 12 September 2020, T . Mehmood , K . Verma & Y. P Sharma TM / KV/YPS 20-001 ( CAL 1837 , holotype) .

Description:— Pileus 60–130 mm diam., convex to plano-convex with broadly depressed centre, gradually becoming infundibuliform; surface smooth, dry, shiny, dull white to smoke grey (3C2), brownish grey (4D2), turning slightly pinkish white (7A2), faintly zonate; sometimes with white tomentum when young, never peeling easily; sometimes cracked towards the margin, brittle in consistency; margin inrolled to incurved. Gills 2–4 mm broad, decurrent to subdecurrent, rather crowded (10–13/cm including lamellulae), rarely anastomosing, reddish grey (7B2), pinkish white (8A2), edges entire; lamellulae present in 3–4 lengths. Stipe 16–40 × 20–30 mm, central, cylindrical, sometimes slightly swollen at the base, dry, white to dull white. Context moderately thick at pileus, white, solid in stipe, turning yellowish white (1A2), 3% KOH, deep red (10C8) with guaiac, olive (1E3–4) with FeSO 4. Latex copious, white, unchanging, greyish yellow (2C4–5) with KOH. Taste mild. Odour pleasant.

Basidiospores 8.0–9.2–11.5 × 5.5–6.7–8.0 μm (n = 40, Q = 1.06–1.38–1.66), broadly ellipsoid to ellipsoid, composed of irregular ridges (up 0.8 μm high) and some warts forming an almost complete reticulum, sometimes with little isolated warts; hilar plage inamyloid. Basidia 34.4–57 × 9.4–11 μm, clavate to subclavate, hyaline, thin-walled, 4-spored; sterigmata 4.3–6 × 0.5–1 μm. Pleuromacrocystidia moderate to abundant, 54–74 × 5–7.5 μm, emergent up to 4–9 μm, mostly embedded in the hymenium layer, sublanceolate, subfusiform, moniliform, acuminate to subobtuse apices. Gill edge sterile. Cheiloleptocystidia 29–38 × 5–6 μm, emergent up to 10–18 μm. Cheilomacrocystidia scarce, 35–50 × 4.0–5.0 μm, subfusiform, obtuse apex. Pseudocystidia 4–6 μm wide, emergent up to 5–7 μm, cylindrical to tortuous, sometimes acute at apex, moderate to abundant. Hymenophoral trama composed of abundant lactifers and sphaerocytes with connecting hyphae and 40–60 μm thick. Pileipellis up to 145–163 μm thick, an ixocutis, composed of loosely interwoven thin-walled, septate, branched, repent hyphae (3–4 μm wide) under a very thin layer of gluten (10–15 μm) having abundant lactifers. Stipitipellis up to 54–90 μm thick, an ixocutis composed of interwoven, septate, thin-walled hyphae under a very thin layer of gluten; hyphae 3–5 μm wide. Clamp connections absent in all tissues.

Habitat and distribution:—Solitary to scattered, growing in associations with Salix alba and Populus sp.

Specimens examined:— INDIA. Ladakh , Kargil, Drass, 3117 m elev., “ N 34°25ʹ 36. E 75°44ʹ 45. 13, 12 September 2020. T. Mehmood, K. Verma and Y. P Sharma, TM /KV/YPS 20-001, TM /KV/YPS 20-002, TM /KV/YPS 20-003 .

Notes:— Lactarius drassinus is characterized by its dull white to greyish brown, faintly zonate pileus; decurrent to subdecurrent, rather crowded, pinkish white lamellae; copious, white latex, mild taste; broadly ellipsoid to elongate basidiospores (8.0–11.5 × 5.5–8.0 μm) with ornamentations composed of ridges (0.8 μm high) and warts forming an almost complete reticulum; moderate to abundant pleuromacrocystidia (54–74 × 5–7.5 μm) mostly embedded in the hymenium layer; very scarce cheilomacrocystidia, ixocutis-type pileipellis composed of loosely interwoven thin-walled hyphae. The presence of a less viscid to dry, faintly zonate pileus, pinkish white lamellae; ixocutis-type pileipellis and stipitipellis place this species, morphologically, in L. section Zonarii Quel. ( Heilmann-Clausen et al. 1998).

Lactarius drassinus resembles Lactarius controversus which was originally reported from Europe. However, the presence of a viscid to greasy pileus surface, adnate to slightly decurrent lamellae, pale cream to dark pinkish discoloration of stipe, acrid taste and smaller (5.8–8.5 × 4.2–5.9 um) basidiospores with shorter ridges (0.5 μm high) and rather scarce pleuromacrocystidia in L. controversus separate it from L. drassinus ( Heilmann-Clausen et al. 1998) .

Figures

FIGURE 5. Lactarius drassinus. a–b. Basidiomata in the field; c. Latex; d. Cheiloleptocystidia; e. Cheilomacrocystidia; f. Basidia; g. Pseudocystidia;h.Pleuromacrocystidia;i.Transverse section throughpileipellis;j.Basidiospores underlightmicroscope;k,l. Basidiospores under SEM. Scale bars: a–c=20 mm, d–j = 10 μm. k=2 μm, l=1 μm. Photos a–c by: Y. P Sharma and d–l by: Komal Verma.

FIGURE 6. Lactarius drassinus. a. Basidia; b. Basidiospores; c. Pseudocystidia; d. Pleuromacrocystidia; e. Paracystidia; f. Pileipellis. Scale bars: a, c–f =10 μm, b=1 μm. Drawings by: Tahir Mehmood.