Lactarius glabrigracilis Wissitrassameewong & Nuytinck, 2014

Wisitrassameewong, Komsit, Nuytinck, Jorinde, Hampe, Felix, Hyde, Kevin D. & Verbeken, Annemieke, 2014, Lactarius subgenus Russularia (Russulaceae) in South-East Asia: 2. Species with remarkably small basidiocarps, Phytotaxa 188 (4), pp. 181-197 : 191-193

Lactarius glabrigracilis Wissitrassameewong & Nuytinck sp. nov. ( Figs 4 & 6D )

MycoBank: MB 808629

Typus:— THAILAND, Chiang Mai province, Muang district, Suthep sub-district, Doi Suthep-Pui National Park , Sangasabhasri Lane to Huai Kok Ma village , 1145 m elev., N18 48.62 E98 54.60, 2/7/2011, KW093 (holotypus GENT!, isotypus MFLU!)

Pileus 5–40 mm diam., at first broadly convex to applanate, infundibuliform with age, with a distinct papilla in the center; margin strongly striate, mostly inflexed, rarely reflexed, crenate to crenulate; surface moist to dry, translucent, slightly hygrophanous, brown (6 E 5) when young, light brown (7D7) to brown (7 E 7) to reddish brown (8D8 to 8 E 7) on papilla or in center, cinnamon, grayish orange (6 B 5) to brownish orange (6 C 5– C 6) to reddish gold (6 C 7) to light brown (6D6–D7), paler towards margin, brownish orange (6 C 7) and darker in the grooves. Lamellae decurrent, subdistant, 0.5–1.5 mm broad, with 2–4 series of lamellulae, pale yellow (4 A 3–5 A 3), grayish orange (5 A 4– B 4) to brownish yellow (5 C 5) when bruised. Stipe 10–50 × 0.5–3 mm, cylindrical, sometimes slightly broader at the base, slender; surface, smooth, brown (6D7–D8), often paler at top, orange yellow (4 A 3– A 4); strigose but not whitish at base. Context in pileus very thin, 0.5–1 mm broad, hollow in stipe, yellowish white (4 A 2), grayish green (26D5) with 10%KOH, light brown (6D5) with FeSO 4; smell like the European L. quietus ; taste mild. Latex often sparse, watery white, unchanging on exposure, unchanging on tissue paper, handkerchief and with 10%KOH; taste mild.

Basidiospores globose to subglobose to ellipsoid; 6.4– 7.0–7.5 –8.2 × 5.8– 6.3–6.6 –7.3; Q = 1.03– 1.11–1.13 –1.25 (n=80); ornamentation amyloid, composed of irregular ridges up to 1 µm high, often interconnected by thin lines, forming an incomplete reticulum, occasionally subreticulate; elongated to rounded isolated warts numerous, sometimes grouped; plage mostly slightly distally amyloid. Basidia 43–55 × 12–16 µm, mostly subclavate, rarely clavate, somewhat slender, generally 4−spored, sometimes 1−or 2−spored, mostly with granular or guttate contents; sterigmata 7–11 × 2–3 µm. Pleuromacrocystidia fairly abundant, 35–53 × 9–15 µm, not emergent, variable from narrowly fusiform to subclavate; apex short to long mucronate. Pleuropseudocystidia abundant, 3–5 µm diam., aseptate, slightly emergent to emergent, rather straight to tortuous, sometimes branching at apex. Lamellae edge sterile, composed of marginal cells and cheilocystidia; marginal cells abundant, 15–29 × 8–12 µm, mostly cylindrical, sometimes slightly broader at apex; cheilocystidia present but not emergent, 30–40 × 8–12 µm, narrowly irregularly fusiform; apex (sub)mucronate. Hymenophoral trama consisting of sphaerocytes and lactifers. Pileipellis an epithelium, 30–60 µm thick; suprapellis consisting of round cells; subpellis consisting of cylindrical to inflated hyphae. Stipitipellis a cutis; composed of cylindrical to inflated hyphae which are mainly parallel, 3–20 µm diam., septate, thin-walled.

Diagnosis: this species is recognized by its small pileus with a very acute papilla and distinct striation, its very slender and long stipe and an epithelium as pileipellis structure.

Habitat: gregarious on rotten wood or on soil under leaf litter in montane broad-leaved forest dominated by Castanopsis spp. and Lithocarpus spp.

Etymology: —reminiscent of L. gracilis but without hairs (on the pileus).

Studied material: THAILAND, Chiang Mai province, Muang district, Suthep sub-district, Doi Suthep-Pui National Park , Sangasabhasri Lane to Huai Kok Ma village , 1145 m elev., N18°48.62 E98°54.60, 2/7/2011, KW093 (holotype GENT!, isotype MFLU!);−ibid., 2/7/2011, KW095 ( GENT!, MFLU!) ;− ibid., 2/7/2011, KW097 ( GENT!, MFLU!) ;− ibid., 2/7/2011, KW101 ( GENT!, MFLU!) ;− ibid., 29/6/2012, KW321 ( GENT!, MFLU!) ;− ibid., 5/7/2012, KW335 ( GENT!, MFLU!) ;− ibid., 16/7/2012, KW358 ( GENT!, MFLU!) , THAILAND, Chiang Mai province, Mae-On district, Pa Mieang sub-district Thep Saded Waterfall, Mae Takraii National Park , 1150 m elev., N18°55.32 E99°21.31, 1/6/2012, KW230 ( GENT!, MFLU!) , THAILAND, Chiang Mai Prov., Jomthong district, Doi Inthanon National Park, junction of Highway 1009 and road to Mae Chem district , 1700 m elev., N19°31.58’ E 98°29.64’, 25/6/2004, LTH141 ( GENT!, CMU!, SFSU!) ;− ibid., 25/6/2004, LTH142 ( GENT!, CMU!, SFSU!) ;− ibid., 27/6/2005, LTH327 ( GENT!, CMU!, SFSU!) .

Comment: —This species was mentioned in Le (2007) as Lactarius aff. obscuratus . Among the small species, it is one of the most commonly observed species in Thailand, together with L. gracilis . L glabrigracilis has the same stature and colours as L. gracilis , but differs by the lack of hairs on the margin of the pileus, a striking character for L. gracilis . Under the microscope, L. gracilis differs from this new species in possessing a cutis as pileipellis, and emergent and larger pleuromacrocystidia.

Figures

FIGURE 4. L. glabrigracilis (KW093): a. basidiospore, b. basidia, c. pleuromacrocystidia, d. lamellae edge, e. cheilocystidia, f. pseudocystidia, g. pileipellis (scale bar = 10 μm).

FIGURE 6: Basidiocarps; A–B: L. crenulatulus (Photo A: Todd Elliott), C: L. perparvus (Photo: Todd Elliott), D: L. glabrigracilis (Photo: Felix Hampe), E: L. gracilis (Photo: Felix Hampe)