Introduction to Fungi, Third Edition

AERO-AQUATIC FUNGI
697
Table 25.3. Examples of the taxonomic diversity of aero-aquatic fungi.
Anamorph genus Teleomorph genus Taxonomic affinity
Oomycota
Medusoides (oogonium) Pythiogetonaceae (Pythiales)
Ascomycota
Clathrosphaerina Hyaloscypha Helotiales
Helicoon Orbilia Orbiliaceae
Helicodendron Mollisia, Hymenoscyphus Helotiales
Helicodendron Lambertella, Herpotrichiella Chaetothyriales (see p.484)
Helicodendron Tyrannosorus Dothideales (Loculoascomycetes)
Pseudaegerita Hyaloscypha Helotiales
Basidiomycota
Aegerita Bulbillomyces Polyporoid clade
Aegeritina Subulicystidium Polyporoid clade
(Unknown) Limnoperdon (basidiocarp) Gasteromycetes
Akenomyces (Sclerotium) (Unknown) Incertae sedis
of aero-aquatic fungi form microconidial synanamorphs
in culture, the spores of which fail
to germinate. These are probably spermatia.
25.3.1 Development of propagules
There are various ways in which conidia of aeroaquatic
hyphomycetes may develop. In Helicoon
(Fig. 25.21a) they develop as cylindrical or barrelshaped
spirals. The conidia vary in colour
from hyaline to black. The direction of coiling
of the spirals (looking upwards from the apex of
the conidiophore) is clockwise in H. richonis
whereas in some other helicosporous fungi the
direction of coiling is counter-clockwise. The
direction appears to be constant for a given
species. In Helicoon the conidia themselves do
not branch, but in Helicodendron (Hd.) which is
clearly a polyphyletic anamorph genus, the
conidia may bear further conidia as lateral
branches (Figs. 25.21b,c; 25.22a). Beverwijkella
pulmonaria, probably an anamorphic ascomycete
(Fig. 25.23a), forms uni- or bi-lobed, balloon-like
structures. At the surface, aggregates of dark,
thick-walled, tightly packed cells develop, with
air trapped inside the cavity which they enclose
(Michaelides & Kendrick, 1982). Spirosphaera,
another anamorphic ascomycete, achieves the
same end by the formation of globose
propagules made up of richly branched,
incurved hyphae (Fig. 25.23b). Yet another way
of entrapping air within the propagule is
shown by Clathrosphaerina zalewskii which forms
hollow, spherical propagules with a lattice wall,
resembling practice golf balls. These clathrate
structures are formed by the repeated dichotomy
of the arms of the developing conidium, which
then curve inwards and join firmly where
the tips of the arms touch (Figs. 25.22b, 25.24).
This fungus has a minute inoperculate discomycete
teleomorph, a species of Hyaloscypha
whose apothecia develop in air on twigs or
pieces of wood which have previously been
submerged.
Several bubble-trap propagules are also
known among Basidiomycota. An example
is Aegerita candida (teleomorph Bulbillomyces
farinosus), which forms its conidia (bulbils)
and basidia on the surface of wet, previously
submerged wood. The propagule is made up
of tightly clustered aggregates of inflated,
dikaryotic clamped cells between which air is
entrapped (see Figs. 18.8 and 25.22c). The
propagules of Aegeritina tortuosa (teleomorph
Subulicystidium longisporum) which also grows on
wet wood resemble those of A. candida but are
not clamped.