History of name:
Laccaria pumila
Fayod, Annali Accad. Agric. Torino 35: 91. 1893. Clitocybe pumila (Fayod)
Saccardo, Syll. Fung. 17: 13. 1905. Laccaria laccata var. pumila (Fayod)
Favre, Ergebn. Wiss. Unters. Schweiz. NatnParks V, 33:51. 1955 [not val. publ., basionym
not mentioned).
Laccaria altaica Singer, Bull. Soc. Mycol. France 83: 122. 1967.
Misapplied names: Laccaria striatula sensu Singer, Mycologia 35: 151. 1943;
sensu auct. plur. -- Laccaria tortilis sensu M. Lange, Meddel. Grønland
147: 29. 1955; sensu Miller et al., Mycologia 74: 583. 1982.
Type: FRANCE: dept. Alpes maritimes, Col de la Cayolle, 2500 m alt., 18 July 1976,
J. Trimbach 1463 (L!, neotype fide Mueller & Vellinga, 1986).
Species Synopsis:
Pileus very small to small (rarely up to 30 mm broad), often strongly striate, subglabrous,
brownish orange. Lamellae pinkish orange brown. Stipe subconcolorous with pileus;
basal mycelium white. Basidia bearing 2-sterigmate. Cheilocystidia usually lacking.
Basidiospores large (up to 17 µm long excluding ornamentation), subglobose to
broadly ellipsoid, echinulate; spines mostly 0.5-1.4 µm long. Predominantly
in alpine, arctic, or boreal habitats.
Habitat and Distribution:
Scattered to gregarious, occasionally caespitose; in poor soil, humus or among mosses;
under Pinaceae, Betula or Salix; restricted to arctic, boreal, and
montane regions, common. See Specimens Examined
for the list of specimens studied.
Observations:
Laccaria pumila appears very similar in the field to L. montana,
L. tortilis, and small striate forms of L. laccata var.
pallidifolia. It can easily be distinguished, however, by its 2-sterigmate
basidia which bear large, subglobose to broadly ellipsoid, echinulate basidiospores.
Laccaria pumila has most commonly been reported under the name L. altaica
Singer. As discussed by Mueller and Vellinga (1986), the name L. pumila has
priority. Another name occasionally misapplied to this taxon is L. striatula sensu
Singer non Peck (e.g., Singer, 1943b; Orton, 1960; Laursen and Chmielewski,
1982).
The major distinguishing character between L. pumila and L.
montana is that the latter has 4-sterigmate basidia. Both are restricted to
arctic, subarctic, alpine and boreal habitats and can be found growing sympatrically.
Singer (1977) mentioned that L. pumila may only be a two-spored form
of L. montana and thus the two might be conspecific. Lahaie (1981)
and data accumulated during this study, however, have supported separation of these
taxa at the species rank. In all specimens examined for this study, no basidiomata
were found which had both 2- and 4-sterigmate basidia, and Lahaie (1981) only reported
one collection in which both 2- and 4-sterigmate basidia were observed.
To date it has not been possible to obtain a tissue culture or to germinate the basidiospores
of L. pumila.
Laccaria pumila appears to be the dominant, if not the exclusive, 2-sterigmate
Laccaria found in the arctic, and the most common 2-sterigmate Laccaria
found in the mountains of western United States. Lange (1955) and Kobayasi et
al. (1967) reported L. tortilis occurring in the arctic, however,
the descriptions and illustrations of both indicate that the collections are probably
L. pumila.
Macromorphology: Pileus
3-27(-40) mm broad, convex to plane, occasionally uplifted, often depressed, usually
strongly translucent-striate when fresh, glabrous to finely fibrillose, occasionally
becoming fibrillose-scaly with age, hygrophanous, red brown to orange-brown ("Hay's
Russet," "Burnt Sienna," or Sanford's Brown"), fading to buff
(near "Xanthine Orange," "Flesh-Ocher" or "Salmon Buff");
margin incurved to decurved, often becoming plane, entire to undulate, occasionally
eroded; context thin, concolorous. Lamellae sinuate to arcuate, distant, thick,
waxy appearing, * 8 mm broad, pinkish flesh color ("Flesh Color" or "Pale
Flesh Color"). Stipe 4-61(-100) x 2-5(-9) mm, equal to subclavate, often
slightly bulbous, occasionally caespitose, dry, fibrillose, longitudinally striate,
± concolorous with pileus, fading to ochraceous buff ("Amber brown,"
"Flesh-Ocher" or "Apricot Buff:). Basal mycelium white. Basidiospores
white in mass.
Micromorphology:
Pileipellis of interwoven hyphae with widely scattered fascicles of ±
perpendicular hyphae; fascicles composed of 10-25 hyphae; terminal cells of fascicular
hyphae 36.5-64 x 8-16 µm, filamentous, subclavate or clavate; walls up to 0.5
µm thick, light yellowish brown, often encrusted with pigment(s); contents hyaline
to light yellowish brown. Pileus trama tightly interwoven, morphologically
undifferentiated, hyaline, light yellowish brown toward pileipellis. Lamellar
trama parallel to subparallel; hyphae mostly 3-18 µm diam, thin-walled,
hyaline to light yellowish brown; cells barrel-shaped. Subhymenium morphologically
undifferentiated. Basidia 37.5-64.5 x 10.5-16 µm, clavate, hyaline; sterigmata
2(-4), up to 14 µm long. Cheilocystidia 27.5-46 x 3 µm, filamentous
to subclavate, hyaline, found in one collection only. Basidiospores (excluding
ornamentation) [86/6] (10-)11-16.5( 20) x (7.8-)10-14.5(-16) µm [ = 12-13(-16.3)
x 10.8-13.8 µm], Q = 1-1.29 [ = 1.1-1.19], subglobose to broadly ellipsoid,
occasionally globose or ellipsoid, hyaline, echinulate; echinulae < 0.5-1.4 (-1.8)
µm long, crowded; hilar appendix 1.3-2 µm long, prominent, truncate; plage
present; contents occasionally uniguttulate. Basal mycelium hyphae mostly
4-19 µm diam, tightly interwoven, hyaline; cells filamentous to barrel-shaped.