History of name:
Laccaria oblongospora
G. M. Mueller, Mycotaxon 20: 108-112. 1984. Type: U.S.A.: Mississippi, Harrison
Co.; DeSoto National Forest, Harrison Experimental Forest, Road H-8, 7 December 1980,
G. M. Mueller 1102 (TENN 42522) (TENN!, holotype).
Species Synopsis:
Pileus 12-60 mm broad, not striate, often fibrillose-scaly, brownish orange, occasionally
vinaceous. Lamellae pinkish flesh color. Stipe mostly 20-60 X 2-12 mm, concolorous
with pileus; basal mycelium violet, soon fading to white. Basidia 4-sterigmate. Cheilocystidia
absent or scattered and undifferentiated. Basidiospores 7.4-10 X 5-7 µm (excluding
ornamentation), ellipsoid to oblong, echinulate; spines mostly <0.5 µm. Southern
Mississippi under long leaf pine.
Habitat and Distribution:
Gregarious; in very sandy soil under Pinus palustris Miller; Gulf Coast.
See Specimens Examined for a list of specimens
studied.
Observations:
Laccaria oblongospora often appears similar to L. proxima
or L. trichodermophora in the field. It differs from L. proxima
in basidiospore shape and size, basal mycelium color and cultural features. It can
be distinguished from L. trichodermophora primarily on basidiospore shape
and echinulae length.
Much variation in basidioma color was observed in this taxon. Most specimens exhibited
the typical orange-brown coloration of L. laccata sensu lato.
Scattered among these were a few individual fruitbodies which were vinaceous to violaceous
in color (e.g., TENN 42524). Initially, these vinaceous collections were thought
to represent a separate taxon. However, due to the occurrence of intermediate color
forms (orange brown pilei and stipes with violaceous lamellae) and identical culture
mat morphologies, they have been treated as contaxic.
Intercollection pairing studies have supported treating L. oblongospora as
a separate species. Isolates from the two stocks obtained during this study are intercompatible
with each other but intersterile with all tested isolates of other species including
isolates of L. proxima. Material of L. oblongospora was not included
in the analyses of mtDNA or rDNA RFLPs.
Laccaria oblongospora was consistently placed in Laccaria metasection
Laccaria during cladistic analyses. Phylogenetic relationships between the
taxa in this metasection, however, were not resolved during these analyses. If this
is the correct placement of L. oblongospora, the pigment(s) responsible for
the violet mycelium at stipe bases and culture mats would be pleisiomorphic and would
not be informative for resolving relationships within the genus (see PHYLOGENETIC
CONSIDERATIONS for further discussion).
Only a few populations of this species have been located. All of them were either
in eastern Texas or southern Mississippi. Several of these populations were very
large and consisted of numerous basidiomata. Specimens of L. oblongospora
have only been encountered near stands of Pinus palustris.
Macromorphology:
Pileus (5-)12-59 mm broad, obtuse to convex, becoming plane to uplifted, often
depressed, not striate, finely fibrillose, becoming fibrillose-scaly, hygrophanous,
brownish orange ("Vinaceous-Rufous," "Kaiser Brown," "Apricot
Buff," "Burnt Sienna" or "Sanford's Brown"), occasionally
vinaceous color ("Vinaceous-Brown," "Vinaceous-Russet" or "Japan
Rose"); disc often darker, red brown to dark orange-brown or occasionally vinaceous
("Dark Livid Brown," "Deep Brownish Vinaceous," "Hay's Russet,"
"Chocolate," "Vinaceous-Russet" or "Mahogany Red");
margin incurved to decurved, becoming plane to uplifted, entire to undulate, occasionally
becoming eroded; context 1-2 mm thick, tapering quickly to margin, flesh color ("Pale
Vinaceous-Pink"). Lamellae sinuate to adnate, occasionally arcuate, subdistant
to distant, broad, thick, pinkish flesh color ("Vinaceous-Pink," "Buff-Pink,"
"Light Congo Pink" or "Shell Pink"), occasionally vinaceous or
violaceous ("Light Brownish Vinaceous," "Pale Brownish Vinaceous"
or "Light Pinkish Lilac"). Stipe (11-)20-60(-65) x 2-12 mm, equal
to subclavate, often slightly bulbous, dry, fibrillose, occasionally finely longitudinal-striate,
concolorous with pileus; striations occasionally darker ("Pecan Brown").
Basal mycelium violet, soon fading to white. Basidiospores white in
mass.
Micromorphology:
Pileipellis of loosely interwoven hyphae with scattered large fascicles of
± perpendicular hyphae; fascicles composed of (5-)10-30 or more hyphae; terminal
cells 32.5-71 x 7-24.5 µm, filamentous, subclavate, clavate, broadly clavate
or capitate; walls up to 0.5 µm thick, light vinaceous; contents hyaline to
light yellowish brown or light vinaceous. Pileus trama tightly interwoven,
morphologically undifferentiated, hyaline, yellowish brown to light vinaceous toward
pileipellis. Lamellar trama parallel; hyphae 3-10 µm diam, thin-walled,
hyaline to light yellowish brown; cells barrel-shaped. Subhymenium morphologically
undifferentiated. Basidia 24-35 x 6.5-10 µm, clavate, hyaline; sterigmata
4, up to 5.5 µm long. Cheilocystidia 31.5-53 x 3-7 µm, filamentous
to subclavate, scattered, thin-walled, hyaline, found only in some collections. Basidiospores
(excluding ornamentation) [75/5] 7.4-10 x 5-7 µm [ = 8.3-9.1 x 5.6-5.9 µm],
Q = 1.3-1.76 [ = 1.45-1.60], ellipsoid to oblong, occasionally subreniform, hyaline,
echinulate; echinulae < 0.5(-1.4) µm long, those > 0.5 µm long restricted
to basidiospore apex, crowded; hilar appendix 1.3-2 µm long, prominent, truncate;
plage present; contents occasionally uniguttulate. Basal mycelium hyphae
mostly 3-11 µm diam, tightly interwoven, hyaline; cells filamentous to barrel-shaped.
Somatic Culture Mat Morphology
(n=5; Appendix B):
PDA: Radius at week 3 = 28-39 mm, week 6 = 45-78 mm; mat felty, thick,
tightly interwoven, with scattered small sectors of longer, loosely interwoven hyphae,
tightly appressed to agar surface, in time forming pruinose aerial layer away from
plug, not translucent, at first dark violet, soon fading, week 3 = light to moderate
violet coloration restricted either to 2-3 mm band near margin or 4-5 mm zone near
plug, most of mat light orange-brown, week 6 all light orange-brown, no violet coloration
present; margin up to 5 mm broad, silky to subfelty, thin, uneven, light violet,
becoming white; plug concolorous with mat; hyphae mostly morphologically
undifferentiated, occasionally irregularly swollen, subcoralloid or coralloid. MMN:
Radius at week 3 = most 48-56 mm, one isolate 30-36 mm, week 6 = most covering
agar surface, one isolate 58-78 mm, mat subfelty to subwoolly, thin, becoming
thicker, loosely interwoven, some with subwoolly to woolly or cottony narrow strands
radiating out from the plug to margin, between strands thin, tightly appressed to
agar surface, translucent, becoming somewhat translucent, at first light violet,
soon fading to light violet or white, margin not well differentiated, thin,
uneven, concolorous; plug concolorous; hyphae most morphologically
undifferentiated, occasionally irregularly swollen, subcoralloid or coralloid. MEA:
Radius at week 3 = 26-40 mm, week 6 = 51-78 mm; mat subfelty, thin, loosely
interwoven, some with 1-3 narrow, slightly thicker concentric bands, tightly appressed
to agar surface, translucent, white; margin 1-2 mm broad, not well differentiated,
even to uneven, white; plug white; hyphae morphologically undifferentiated,
occasionally irregularly swollen or subcoralloid.