History of name:
Agaricus ohiensis
Montagne, Syll. Crypt.: 100. 1856. Clitocybe ohiensis (Montagne)
Saccardo, Syll. Fung. V.: 181. 1887. Laccaria ohiensis (Montagne) Singer,
Mycologia 38: 688. 1946.
Clitocybe tortilis var. gracilis Peck, Annual Rep. New York
State Bot. 67: 36. 1903.
Laccaria tetraspora Singer, Mycologia 38: 689. 1946. Laccaria tetraspora
var. tetraspora Singer automatically established by var. valdiviensis
Singer, Bull. Soc. Mycol. France 83: 113. 1967. Laccaria tetraspora var. tetraspora
f. tetraspora Singer automatically established by f. major Singer,
Bull. Soc. Mycol. France 83: 113. 1967.
Laccaria tetraspora var. valdiviensis Singer, Bull. Soc. Mycol.
France 83: 113. 1967.
Laccaria tetraspora var. peullensis Singer, Bull. Soc. Mycol.
France 83: 113. 1967.
Laccaria tetraspora var. scotica Singer, Bull. Soc. Mycol. France
83: 114. 1967. Laccaria scotica (Singer) Bon, Doc. Mycol. 11: 23. 1981 [not.
val. publ., basionym lacking].
Laccaria tetraspora var. xena Singer, Bull. Soc. Mycol. France
83: 116. 1967.
Laccaria tetraspora var. aberrans Singer, Bull. Soc. Mycol.
France 83: 116. 1967.
Laccaria tetraspora var. tetraspora f. major Singer, Bull. Soc.
Mycol. France 83: 113. 1967.
Type: U.S.A.: Ohio, Columbus, before 1856, Sullivant s.n. (PC!, holotype).
Species Synopsis:
Pileus 7-26 mm diam, plicate-striate, strongly striate, reddish brown. Lamellae pinkish
flesh color. Stipe 12-25 x 1-2 mm, glabrous, concolorous with pileus. Basidia 4-sterigmate.
Cheilocystidia 20-55 x 3-5.5 µm, absent to abundant. Basidiospores mostly 7.7-9.4
µm diam, globose to subglobose, echinulate; spines 1.5-2.8 µm long, >
1.2 µm wide at base. Found uncommonly throughout North America.
Habitat and Distribution:
Scattered to gregarious, not commonly collected in boreal or north temperate habitats.
Commonly reported from subtropical, tropical and south temperate regions. See Specimens Examined for the list of specimens studied.
Observations:
Collections of Laccaria ohiensis are characterized by their small basidioma
size; strongly striate pilei; short, concolorous stipes; and globose basidiospores
with long and wide echinulae.
Laccaria ohiensis is primarily differentiated from Laccaria laccata
var. pallidifolia by having basidiospore echinulae that are ³ 1.2 µm
wide at their base. In contrast to L. ohiensis whose collections are relatively
uniform in macro- and micromophological features, collections of L. laccata
var. pallidifolia are highly variable in most morphological characters. Collections
of L. laccata var. pallidifolia with small basidiomata and globose
basidiospores (characteristics of L. ohiensis) are occasionally encountered.
Tested homokaryotic isolates of these two taxa are intersterile (Fries and Mueller,
1984; Mueller, 1991c) and differ in mtDNA and rDNA RFLP patterns (Gardes et al.,
1990, 1991a; Mueller, 1991c). Isolates identified as belonging to mating group III
(Fries and Mueller, 1984) and intersterility group 4 (Gardes et al., 1990,
1991a; Mueller, 1991c) are referable to L. ohiensis.
Laccaria ohiensis is differentiated from L. striatula by differences
in macromorphology. Basidiomata of L. striatula have relatively long, glabrous
stipes which are darker in color than the strongly striate pilei. Collections of
these two taxa were not segregated during morphometric analyses of basidiospore characters
(Mueller, 1991c) but tested isolates of the two taxa are intersterile. The isolate
of L. ohiensis included in the analyses of mtDNA and rDNA had unique RFLP
patterns (Gardes et al., 1990, 1991a).
The holotype of L. ohiensis consists of basidiomata which have globose, echinulate
basidiospores born on 4-sterigmate basidia. This agrees with Singer's (1942) description
of the type and Malençon's (1966) and Malençon and Bertult's (1975) concept
of the taxon. In subsequent papers (e.g., Singer, 1946, 1977; Singer and Digilio,
1952; Bon, 1983), L. ohiensis was treated as a taxon with 2-sterigmate basidia.
The correct name for the 2-sterigmate taxon discussed by Singer (1967, 1977) which
has moderate-sized, subglobose basidiospores and normally occurs in warm and dry
regions, often under Eucalyptus, is L. fraterna. Laccaria impolita
is similar to L. fraterna but differs in macromorphology and association with
north temperate trees.
Macromorphology:
Pileus 7-26(-50) mm broad, convex to plane, often depressed, plicate-striate
and strongly translucent-striate when fresh, glabrous to finely fibrillose, hygrophanous,
reddish brown (near 8D6) soon becoming orange-brown (7C5 6) finally fading to buff;
margin decurved to plane, entire to undulate; context thin, concolorous. Lamellae
adnexed to adnate, distant, moderately thick, pinkish flesh color (6A2-7A3). Stipe
12-25(-40) x 1-2(-6) mm, equal or slightly bulbous, dry, glabrous to finely fibrillose,
astriate to slightly longitudinally striate, concolorous with pileus. Basal mycelium
white. Basidiospores white in mass.
Micromorphology:
Pileipellis of interwoven hyphae with widely scattered fascicles of ±
perpendicular hyphae; fascicles composed to 5-30 hyphae; terminal cells of fascicular
hyphae 26-67 x 5-17.5 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 2-10 µm diam, thin-walled,
hyaline to light yellowish brown; cells barrel-shaped. Subhymenium morphologically
undifferentiated. Basidia 28-60 x 8-16 µm, clavate, hyaline; sterigmata
4, up to 10 µm long. Cheilocystidia 20-55 x 3-5.5 µm, filamentous
to subcapitate, absent to relatively abundant, thin-walled, hyaline. Basidiospores
(excluding ornamentation) [375/11] (6.4 )7.7-9.4(-11) x (6.4-)7-9(-10.6) µm
[ = 7.9-8.4(-9.3) x 7.8-8.4(-9.1) µm], Q = 1-1.09(-1.2) [ = 1-1.05], globose
to subglobose, rarely broadly ellipsoid, hyaline, echinulate; echinulae (1-)1.5-2.8
µm long, > 1.2 µm wide at base, crowded; hilar appendix 1.3-2 µm
long, prominent, truncate; plage present; contents occasionally uniguttulate.