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 Marasmius rosulatus
BiostatusPresent in region - Indigenous. Endemic
Images (click to enlarge)
Caption: Marasmius rosulatus. A, Basidiomata (x20). B, Basidiospores (x2000). C, Basidia and basidioles.
D, Cheilocystidia. E, Pileipellis elements. (C-E x1000) |
Article: Desjardin, D.E.; Petersen, R.H. (1989). Two new Marasmius species from New Zealand. New Zealand Journal of Botany 27(2): 275-279 (http://www.rsnz.org/publish/abstracts.php).
Description: Basidiomata marcescent. Pileus 0.2-0.5 mm
diam, convex, deeply sulcate; surface granulose, white overall. Lamellae adnate
or slightly adnexed, with or without a poorly developed collarium, remote (3-5
complete lamellae), broad, white; edges granulose; lamellulae absent. Stipe
0.5-1 x 0.1 mm, central, curved due to geotropic hymenophore, filiform, terete,
equal, white overall; surface glabrous above, basal region with a few mycelial
hairs, subinsititious, often with a socle-like base surrounded by a small ring
of radiating hairs. Rhizomorphs absent. Odour and taste not recorded.
Basidiospores 7.8-9.6 x 4.0-4.8 µm [x = 8.6
x 4.4 µm, s = 0.5 x 0.3, E = 1.7-2.1, Q = 1.9, sQ = 0.1, n = 20], ellipsoid
or amygdaliform, hyaline, inamyloid, smooth. Basidia 16-20 x 8-10.5 µm, tetrasporic,
broadly clavate. Basidioles broadly clavate. Pleurocystidia absent. Cheilocystidia
common nearest pileus margin, scarce nearest stipe, similar to the pileipellis
elements. Pileipellis hymeniform, of Rotalis-type elements, 12-20 x 8-16
µm, broadly clavate or sphaeropedunculate, hyaline, inamyloid, thin-walled;
diverticula 1.0-2.5 x 0.5-1.5 µm, cylindric-obtuse, hyaline, thick-walled. Tramal
hyphae interwoven in pileus, subparallel in lamellae, 2.5-4.0 µm diam, non-inflated,
non-gelatinous, hyaline, inamyloid or weakly dextrinoid, thin-walled, clamp
connections common; refractive oleiferous hyphae occasional. Stipe tissue monomitic;
cortical and medullary hyphae similar, parallel, 2.0-7.2 µm diam, hyaline throughout,
strongly dextrinoid, thin-walled, smooth; clamp connections absent. Stipe vesture
absent near apex, consisting of a few erect, filiform, mycelial "hairs"
nearest the base; caulocystidia absent. Scattered on senescent leaves of Gahnia
sp. [Cyperales].
Notes: Diagnostic features of M.
rosulatus include: a) minute stature, with pilei reaching 0.5 mm diameter
and stipes up to 1 mm long; b) reduced number of well-developed lamellae (3-5
present, no lamellulae) and a poorly developed (or absent) collarium; c) complete
lack of pigments throughout the basidiomata; d) clamp connections on tramal
hyphae and hymenial elements but absent in stipe tissue; e) strongly dextrinoid
stipe tissue; f) subinsititious stipe with radiating basal mycelial hairs; and
g) growth on senescent leaves of Gahnia.
We were unable to demonstrate the presence
of a collarium in the holotype specimen, but a second, conspecific collection
contains several basidiomata, which readily show a thin layer of tissue connecting
the lamellae and sheathing the stipe apex. Presence of a collarium, albeit very
weakly developed, in combination with dextrinoid stipe tissue and Rotalis-type
pileipellis elements dictates placement in sect. Marasmius subsect. Marasmius
[= subsect. Pararotulae Singer (1976)]. It must be noted, however, that
a subinsititious stipe and a complete absence of pigments exhibited by M.
rosulatus are characters unusual in sect. Marasmius. Within subsect.
Marasmius, M. rosulatus is most phenetically similar to M.
pararotula Sing., described from Bolivia. Both species form minute, white
pilei with few, broad lamellae. Marasmius pararotula differs in forming
a deep umber, longer (5-12 mm) and strictly insititious stipe, more lamellae
(5-8), broader spores (4.8-5.5 µm diam.), and in growing on leaves of dicotyledonous
plants (Fide Singer 1965).
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