MYCORRHIZAE.
Of the almost 1500 soil samples representing ca. 90 plant species
in 28 families, zygosporangia of E. aurantiaca have occurred only in
those taken from the root zone of Pinus sylvestris L. (Blaszkowski
1997). This fungus failed to form new zygosporangia and mycorrhizae in pot cultures
with P. sylvestris.
DISTRIBUTION.
In
Poland, E. aurantiaca has been found in rhizosphere soils of P.
sylvestris growing in the Kampinos National Park (52o18’N, 20o46’E),
the Hel Peninsula (54o36'-54o47'N, 18o25'-18o48'E), Zelistrzewo (54o57'N,
18o13'E; the Pomerania province), Ploty (53o56'N, 14o56'E; the Western
Pomerania province), and Bydgoszcz (53o7’N, 18o1’E; Blaszkowski 1997;
pers. observ.). No report of the presence of this fungus in other regions
of the world exists.
NOTES.
Endogone aurantiaca is distinctive due to the formation
of zygosporangia in loose aggregates or singly in the soil and especially
by its ornamented zygosporangial wall. The characteristic feature of this
species also is the lack of a peridium.
Species of the genus
Endogone forming zygosporangia resembling in colour and size those
of E. aurantiaca are E. alba (Petch) Gerd. & Trappe,
E. flammicorona Trappe & Gerd., and E.
lactiflua Berk. & Broome (Gerdemann and Trappe 1974; Pegler et
al. 1993; Yao et al. 1992). However, these species produce compact sporocarps surrounded by a peridium (vs. loose aggregates without a peridium or single
zygosporangia in E. aurantiaca). The zygosporangia of E. aurantiaca,
E. flammicorona, and E. lactiflua are enclosed by a hyphal
mantle that is absent in E. alba. The hyphal mantle of E. aurantiaca
is formed by interwoven sinuous hyphae. Endogone flammicorona
also has a mantle with a spiral, sinuous pattern when observed in a plan view
(Gerdemann and Trappe 1974). However, in a cross-sectional view, this mantle
resembles a crown or „tongues of flame” produced by hyphal ridges
wider at the base and thinner at the top, being, thereby, unlike the mantle
of E. aurantiaca consisting of 2-6 layers of interwoven hyphae.
The hyphal mantle of
E. lactiflua is reminiscent of the E. aurantiaca mantle
in a cross-sectional view, although it is not spirally arranged as in the
latter species when observed in a plan view.
The most distinctive
feature of E. aurantiaca is its ornamented zygosporangial wall. Except
for E. alba, the other described species of this genus form smooth-walled
zygosporangia (Gerdemann and Trappe 1974; Pegler et al. 1993; Tandy 1975).
The zygosporangial wall of E. alba has a minutely rugulose to almost
reticulate ornamentation, frequently with branching ridges (Yao et al. 1992),
whereas that of E. aurantiaca is covered with conical warts.
Additionally, the features
separating E. aurantiaca from the species listed above are the lack
of reactivity in Melzer’s reagent [vs. zygosporangial wall yellow to
pale orange and crayfish red (9B8) in E. flammicorona and E.
lactiflua, respectively], the hyaline zygospore wall (vs. melon yellow,
hyaline to light yellow, and yellow in E. alba, E. flammicorona,
and E. lactiflua, respectively), and the relatively narrow gametangia
(20-31 µm wide vs. up to 36 µm, up to 40 µm, and up to 80
µm wide in E. alba, E. flammicorona, and
E. lactiflua, respectively).
Apart from E. aurantiaca,
known fungal species of this genus producing sporocarps lacking a peridium
include E. acrogena Gerd., Trappe & Hosford, E.
maritima Blaszk. & Tadych, and E. verrucosa Gerd. &
Trappe (Blaszkowski et al. 1998; Gerdemann and Trappe 1974). Endogone
aurantiaca differs in that it has no zygosporangia arranged either in
chains as in E. acrogena or in clusters enclosed in an endoperidium
as in E. verrucosa. Additionally, the zygosporangia of the latter
two fungi are much smaller than those of the former new species. Endogone
maritima produces smooth-walled zygosporangia.
Endogone aurantiaca
was the first species of the genus Endogone described to form
single zygosporangia in the soil (Blaszkowski 1997), although non-sporocarpic
zygosporangia of E. flammicorona, E. maritima and E.
lactiflua were also recovered (Blaszkowski 1989, 1993; Blaszkowski et
al. 1998; see the discussion in the section “the Endogonaceae”).
REFERENCES
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The occurrence of arbuscular fungi and mycorrhizae (Glomales) in plant communities
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377-392.
Blaszkowski J. 1997.
Endogone aurantiaca, a new species in the Endogonales from Poland.
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Blaszkowski J., Tadych
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