Russulales » Russulaceae » Lactarius

Lactarius acicularis

Lactarius acicularis Van de Putte & Verbeken

MycoBank: MB518942

Basidiocarps medium-sized. Pileus 3585 mm diameter, convex when immature, becoming applanate with slightly depressed centre to infundibuliform when mature, margin regular or waving, surface dry and smooth to slightly rugulose when young, rugose when mature, velutinous or not, pruinose or not, yellowish orange brown (5C75C8), brown (6D5), in the centre darker brown (6F6) or reddish brown in the centre, getting paler and with or without more orange (6C8) or yellowish orange tinges towards the margin, young specimens darker. Lamellae subdecurrent to decurrent, cream (4A34A4), discolouring brown (6D56E5) to greyish brown (5C35C4) when damaged, crowded (1117L+l/cm), narrow to rather broad (1.56 mm), with numerous lamellulae of different length, edge smooth and concolourous. Stipe 4585×515 mm, cylindrical to slightly tapering downwards, centrally attached, surface dry, velutinous or not, pruinose or not, smooth or longitudinally rugulose, yellowish orange (4A55A5), brownish orange (6C86D8) to greyish brownish orange (6C55C66B56B66C6) or brown (6D46D5). Latex copious, sticky, white, slightly watery or not, unchanging when isolated, unchanging on lamellae or within few minutes to half an hour turning brown, no reaction or becoming cream (4A34A44B3) or light brown (6C46C5) with KOH 10%, taste mild. Context moderately thick in pileus, solid to stuffed in stipe, whitish to cream (2A22A3), quickly turning brown to greyish brown (5B35C35C46C26D4) after cut, smell faint to fishy, taste mild. Macrochemical reactions context almost immediately turning

yellowish with KOH 10%, after a few seconds becoming more yellowish orange, greenish grey to bluish

grey (25E225F326D226E3) or olive brown (4D34D4) reaction with FeSO4. Basidiospores 7.07.9–8.59.1(9.3) × μm, subglobose (Q=; ornamentation amyloid; ridges up to 1.4 μm high, with rather sharp edges, forming a rather regular to slightly irregular complete or incomplete reticulum, sometimes isolated warts present; strong amyloidity between the ridges; plage

distally to almost completely amyloid. Basidia 4060×912 μm, clavate, subclavate to subfusiform, 4-spored. pleurolamprocystidia 35100×69(11.5) μm; wall 14 (5) μm; rather short, subfusiform, subclavate, subcylindrical, acuminate or with obtuse apex, occasionally furcate or lobed at the top, emergent or not, arising from the subhymenium, moderately to very abundant. Pleuropseudocystidia

26 μm diam., subcylindrical, often capitate, apex obtuse, occasionally lobed, emergent, scarce to abundant. Lamellae-edge fertile, composed of basidia and cheilocystidia. Cheilocystidia 1585×38 μm; thin-walled and hyaline to thick-walled [0.52.5(3) μm]; fusiform, subfusiform, subclavate or somewhat irregularly shaped, acuminate or with obtuse apex, outline sometimes wavy. Hymenophoral trama cellular, with abundant lactifers and rosettes of sphaerocytes. Pileipellis a lampropalisade; subpellis 50120 μm thick, composed of rounded to elongated or irregularly shaped, thick-walled cells (555×545 μm); terminal elements 15130×38 μm; wall 0.51.5 μm; subcylindrical to subfusiform with tapering apices, acuminate or obtuse apex, outline often wavy, often septate.


Studied material: THAILANDChiang Mai Province, Mae Taeng district, Ban Pha Deng, Pathummikaram Temple, N19°0628.8E98°4447.3, alt. 1050 m, rainforest with Castanopsis armata, Dipterocarpus sp., Lithocarpus sp., 8 July 2008, Van de Putte 08-007 (GENT, MFLU)ibid., 15 July 2008, Van de Putte 08-029 (holotype MFLU, isotype GENT)Chiang Mai Province, Mae Taeng district, Ban Mae Sae Highway 1095 near 50 km marker, N19°14.599 E98°39.456, alt. 1002 m, rainforest with Castanopsis armata, Castanopsis sp., Lithocarpus sp., Pinus kesiya, 28 July 2004, Le 199 (CMU, GENT, MFLU, SFSU)ibid., 4 July 2007, Stubbe 07-456 (CMU, GENT)ibid., 5 July 2008, Van de Putte 08-002 (GENT, MFLU)Chiang Mai Province, Doi Inthanon National Park, junction of Highway

1009 and road to Mae Chem, N19°31.58E98°29.64, alt. 1700 m, humid montane rainforest with Castanopsis sp., Lithocarpus echinops, Quercus sp., 16 July 2008, Van de Putte 08-033 (GENT, MFLU)Chiang Mai. Province, Doi Sa Ket district, N18°5431.5E99°1257.0, alt. 574, rainforest dominated by Castanopsis spp., 12 June 2006, Le 277 (CMU, GENT, MFLU, SFSU)


Note: L. acicularis can be recognized by the combination of the very long pileipellis hairs, the brown to reddish-brown pileus colour and the spores with an ornamentation of 1.4 μm maximum. It can be confused with L. longipilus, which also has distinctly long pileipellis hairs and a reddishbrown pileus. They differ from one another by the height of the spore ornamentation, which can be up to 2.12.3 μm in L. longipilus, but only up to 1.11.4 μm in L. acicularis.

Fig. 1 ML phylogram of Lactarius volemus sensu lato from northern Thailand based on LSU, ITS and rpb2 nuclear sequences. Posterior probability values of the BI-MrModeltest analysis (runs 25) are added. Bootstrap values 75% and posterior probabilities 85% are shown. Underlined taxa occupy uncertain positions. Branches in bold lead to well supported clades. The following abbreviations are used: AV: A. Verbeken, AVRW: A. Verbeken & R. Walleyn, BB: B. Buyck, DED: D.E. Desjardin, DS: D. Stubbe, JV: J. Vauras, KIINA: M. Härkönen, KVP: K. Van de Putte, LTH: H.T. Le, N: M. Noordeloos, RH: R. Halling, RW: R. Walleyn.


Fig. 1 Lactarius acicularis: a. basidiocarps (Le 199), b. basidiospores (holotype), c. section through hymenium (Van de Putte 08-033), d. pseudopleurocystidia, e. basidia (Stubbe 07-456), f. pleurolamprocystidia (holotype, Van de Putte 08-033, 08-007, 08-002) g. cheilocystidia (Le 199, Stubbe 07-456, Van de Putte 08-002) (scale bar = 10 μm, scale bar basidiocarps = 1 cm).