Lactarius lanceolatus O.K. Mill G. Laursen

Jacob Heilmann-Clausen, Annemieke Verbeken & Jan Vesterholt, 1998, The Genus Lactarius, Copenhagen: Danish Mycological Society : 180

Lactarius lanceolatus O.K. Mill G. Laursen

Lactarius lanceolatus O.K. Mill G. Laursen, 1973 : 43. Holotype: Alaska, Beaufort Lagoon (VPI).

A medium-sized Lactarius with white milk; and orange-brownish colours; very similar to L. aurantiacus but occurring in alpine and arctic habitats with dwarf Salix .

DESCRIPTION: Cap 25-55 mm, convex to applanate with a decurved or inrolled margin, later depressed With expanded margin, sometimes with a small umbo or papilla, margin often finely crenulate; surface smooth, dry to sticky or glossy, often becoming mat and areolate-rimose in a concentric pattern, margin at first pruinose, dark brick to brick or orange-brown, darkest in the centre. Gills adnate to slightly decurrent, medium crowded, pinkish buff, later clay-pink to Isabella-coloured. Stem 20-30 x 5-11 mm, cylindric to subclavate; surface smooth, dry, faintly pruinose when young, clay-buff to cinnamon. Flesh fragile, soon hollow in the stem, pale cream to pale pinkish buff, outer part coloured like surface: smell faint or like L. quietus ; taste mild or becoming slightly bitter. Milk White or watery white, unchanging; taste mild or slightly astringent. Spore deposit whitish.

Spores 72-11.3 x 5.6-8.4 pm, av. 8.0-9.8 x 6.5-7.4 pm, subglobose to ellipsoid, Q = 1.05- 1.55, av. 1.21-138; ornamentation 0.3-0.9 pm high, of fine elongate warts, joined by fine lines and low ridges to form an incomplete reticulum, isolated warts numerous; plage inamyloid or with an amyloid distal spot. Basidia 35-60 x 10-13 pm, subclavate, 4-spored. Pleuromacrocystidia scattered to rather abundant, 50-135 x 6.5-10.5(-12) pm, narrowly fusiform to conical, often flexuose to moniliform, apex acute, subacute or mucronate. Gill edge heterogeneous; cheilomacrocystidia numerous, 20-60 x 4-10 pm, fusiform or conical, apex acute or moniliform. Pileipellis an intricate (ixo)trichoderm; terminal elements 15-50 x 2-5 pm, cylindric; subpellis very compact, of darker, slightly swollen hyphae, about 6 um broad.

ECQLOGY AND DISTRIBUTION: In Europe L. lanceolatus is only known from the northernmost part of Fennoscandia. It associates with dwarf Salix and is widely distributed in Greenland, northern North America and probably Siberia.

DISCUSSION: Lactarius lanceolatus is similar to, or maybe even conspecific with L. aurantiacus . Lactarius lanceolatus is often somewhat darker and more reddish than L. aurantiacus , and the cracking of the cap is usually not seen in L. aurantiacus . These differences may be caused by the extreme environmental conditions. Lactarius lanceolatus often has longer macrocystidia and larger, more faintly ornamented spores than L. aurantiacus , but intermediates occur. For further discussion, see Gulden et al. (1988).