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Helicoon gigantisporum sp. nov., and an amended key to the genus

DOI:10.1016/S0953-7562(96)80083-9
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Teik Khiang Goh at National Chiayi University
Teik Khiang Goh
Kevin David Hyde at Mae Fah Luang University
Kevin David Hyde
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Abstract

A new aero-aquatic helicosporous hyphomycete, Helicoon gigantisporum, from submerged wood in Australia is described and illustrated with light and scanning electron micrographs. It differs from the nine previously described species of Helicoon in having larger broadly ellipsoid to doliiform conidia which are borne singly on very short conidiophores. An amended key to the genus is given.
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Mycol. Res. lOO (1,2): L485-7488 (79961 Printed in Great Britain
Helicoon gigantisporum sp. nov., and an amended k"y to the
genus
TEIK,KHIANG GOH1 AND KEVIN D. HYDE'
L Department of Apptied Biology and Chemical Technology, Hong Kong Polytechnlc L)nioersity, Hung Hom, Kowloon, Hong Kong
zDepartment of Ecology and Biodir:ersity, Unioersity of Hong Kong, Pokt'ulam Road, Hong Kong
A new aero-aquatic helicosporous hyphomycete, Helicoon gigantisporum, from submerged wood in Australia is described and
illustrated with light and scanning electron micrographs. It differs from the nine previously described species of Helicoon in having
larger broadly ellipsoid to doliiform conidia which are borne singly on very short conidiophores. An amended key to the genus is
grven.
Figs 6-9. Helicoon gigantisporum. Diagrammatic representation. Fig.
6, Habit sketch of the colony on wood. Fig. 7. Superficial hyphae
with short lateral conidiophores bearing helicoid conidia. Fig. 8.
Three-dimensional sketch of a conidium showing the apex. Note the
counter-clockwise coiling direction. Fig. 9. Three-dimensional sketch
of a conidium showing the base. Note the short hilar projection. Scale
bars 6 : 200 sm, 7-9 : 20 vm.
In a study of the fungi occuring on submerged wood in
streams in north Queensland, Australia, we collected a new
helicosporous hyphomycete. It was identified as a species of
Helicoon (Morgan, -1"892; Coos et a1.,7986) producing solitary,
Figs 1-5. Helicoon gigantisporum. Light micrographs. Fig. 1. Squash
mount illustrating several conidia. Eigs 2-4. Conidia on short
conidiophores. Fig. 5. Glistening conidia on substratum surface.
Scale bars 1-4 : 50 um. 5 : 1 mm.
r485
Helicoon gigantisporum and amended key to the genus 7486
Figs 10-14. Helicoon gigantisporum. Scanning electron micrographs. Fig. 10. A representative portion of the colony on wood. Figs
11-13. Conidia borne on short lateral conidiophores. Note the basal attachment, the 13 x coils, the counter-clockwise coiling direction,
the slight constrictions at septa, and the mucilaginous substances of the conidia. Fig. Ia. Base of a conidium showing the short hilar
projection. Scale bars 10 : 100 gm, 11-14 : 10 Um.
non-proliferating, barrel-shaped conidia bome on distinct
conidiophores. A detailed morphological examination revealed
that this species differed from previously described species of
Helicoon in having larger broadly ellipsoid to doliiform conidia
borne singly on very short conidiophores. An amended key to
the genus is given.
Goos ef al. (1985, 1986) revised the genera Helicodendron
Peyronel and Helicoon A. P. Morgan and discussed the
differences between the two genera. Glen-Bott (1955) listed
five useful criteria for distinguishing species within Helico-
dendron. One of the criteria is the direction of coiling of the
conidial filament which she described as'clockwise'or
'counter-clockwise', depending on the viewer's observation
who is situated outside the spiral, and on its axis. Neither
Goos ef al. fi986\ nor Aa & Samson (1994) indicated the
direction of coiling for the species of Helicoon they described.
It is thought, however, that this criterion is useful and is used
here in the description of our new species.
Microscopic observation and measurements were made
from freshly prepared slides of material mounted in lacto-
phenol. Since the present fungus is aero-aquatic and thus air
bubbles are usually trapped at the centre of the conidia, the
slides were gently flamed several times to remove the trapped
bubbles. To supplement the morphoiogical information, the
T. K. Goh and K. D. Hyde
material has been examined with Cryo-scanning electron
microscopy.
TAXONOMY
Helicoon gigantisporum Goh & K. D. Hyde, sp. nov.
Etym. : Greek g igas, giant
I spora; refernngr" ,^" ,:r:" ;:l
the conidia.
Coloniae in vivo atrobrunneae, nitidiusculae, effusae. Mycelium
partim immersum sed plerumque superficiale. Hyphae superficiales
ca2'5-4 um latae, pallide flavidobrunneae, laeves, ramosae, dense
septatae, ad septas leniter constrictae. Conidiophora macronematosa,
mononematosa, cylindrica, erecta, recta, ex hyphis lateraliter oriunda,
modice flavidobrunnea, non ramos4 non septata, non vermcosa,
6'5-1.4vm longa,3-4'5 um lata uniformia in latitudinibus. Cellulae
conidiogenae monoblasticae, in conidiophoris incolporatae, terminales,
determinatae. Conidia solitana, sicca, acrogena, flavidobrunnea vel
atrobrunnea, helicoidea, distanter septata, corpus ellipsoideum vel
doliiforme, 78-120 um aIfum,4840 gm latum formantia, filamenfum
6'5-10 Um latum, (12-)13 spiris convolutum, frequenter substantia
mucilaginosa consociafum; conidiorum secessio praesumpte schizo-
lytica, ad basim hili protudinem ca 4-9 x 3-4'5 um formans.
Tabfe 1. Differences between Helicoon gigantisporum nd. H. mauosporum
(information from Aa & Samson, 1994)
H. gigantisporum H. macrosporum
1487
Holotypus: on submerged wood in small stream, Mt Lewis, north
Queensland, Australia, May 7995, K. D. Hyde & T. M. Hyde, ML45,
BRIP 23200.
Colony on natural substratum dark-brown, somewhat giisten-
ing, effuse. Mycelium partly immersed but mostly superficial,
consisting of branched hyphae and short conidiophores
bearing conidia; superficial hyphae ca2'5-4 um wide, pale
yellowish-bror rr, smooth, branched, closely septate, slightly
constricted at the septa which are 11-16 um apart. Conidio-
phores macronematous, mononematous, cylindrical, erect,
straight, arising as short branches more or less at right angles
to the subtending hyphae, mid yellowish-brown or somewhat
darker than the subtending hyphae, unbranched, non-septate,
smooth, 6'5-74 um long, 3-4'5 um wide. Conidiogenous cells
monoblastic, integrated, terminal, determinate. Conidia soli-
tary, dry, acrogenous, yellowish-brown to dark-bror,,rn,
helicoid, filament 6'5-70 pm wide, smooth, distantly septate,
slightly constricted at septa, tightly coiled (rz-)r.r times in a
counter-clockwise direction to form a broadly ellipsoidal or
doliiform body, 78-720 um long, 48-90 um wide, usually
incorporated with mucilaginous substances such that no gaps
are visible between adjacent coils; conidial secession pre-
sumably schizolytic at the deliminating septum of the
conidiogenous cell, giving rise to a short hilar projection
ca 44x 3-4'5 um at the base.
Helicoon gigantisporum is recognized as a new species
because of its large doliiform conidia which are bome on very
short conidiophores the lengths of which are never more than
14 um. The conidial body aiways comprises (72-)73 helicoid
tums in a counter-clockwise direction(sensu Glen-Bott, 1955).
Large conidia are also produced by Helicoon macrosporum Aa
& Samson (1,994) and Helicodendron giganteum Glen-Bott
(1951). The latter species is, however, distinct from Helicoon,
by its continuous blastic conidiogenesis (Goos et al., 1985).
Helicoon macrosporum differs from H. gigantisporum in its
narrower conidia and semi-macronematous conidiophores
which are much longer. Moreover, in H. macrosporum, the
. H. sessile
. H. farinosum
. H. auratum
Conidiophore
Length
Conidia
Length of body
Width of body
Number of coils
Direction of coiling
Constriction at septa
6'5*14 Um
78-120 Irm
48-90 Um
(72-)73
Comter-clockwise
Slightly constricted
(30-)70-150(-200) um
(75-)80-110 Um
(39-)45-60 um
(8-)1 1-12(-13)
Clockwise
Not constricted
Amendments Io the key to the Helicoon species of Goos et al. (1986) and Aa €t Samson (1994)
1. Conidia width usually greater than 60 gm; conidiophore length not more than 14 pm, filaments colled (rz-)rl fimes H. gigantlsporum
1. Conidia width less than 60 pm; conidiophore length usually greater than 14 gm, filaments coiled 4-16 times z
2. Conidia white in mass 3
2. Conidia distinctly coloured in mass 4
3. Conidia ellipsoidal, 20-30x33-59 um; filaments 4'54'5 pm, coiled 5-16 times, conidiophores inconspicuous
3. Conidia more or less ovoid in shape, 2O-2Tx22-37 vm; filaments 3.5-4.5 um, coiled 5-8 times
4. Conidia golden yellow in mass 'l-4-27 x 36-46 vm; filaments 2.5-3.6 gm, coiled 8-16 times .
4. Conidia brown to fuscous in mass s
5. Colonies floccose, conspicuous, conidiophores much branched, anastomosing; conidia light brown, 18-32x28-45 vm; filaments
H. elliplicum
5. Colonies lacking floccose mycelium; conidiophores simple or little branched 6
6. Chlamydospores formed on agar media; conidia globose to subglobose, 14-17x 15-18 prm; conidial filament 3-4 um
6. Chlamydospores on agar media lacking H. chlamydosporum
.7
7. Conidial length ranging from 50 to over 100 prm . I
7. Conidial length less than 50 um .
8. Conidia dark fuscous to black 50-87 x 5042 sm; conidial filament 6-10 um, coiled 8-10 times . .H. ichonis
8. Conidia dark brown (75-)80-LLOx(39-)4s4o um; conidial filament 8.5-11 gm, coiled (g-)ff-f2(-13) times .H. macrosporum
9. Conidial filament 2'7-4'5 lrm, coiled, 6-12 times to form an oval conidium, 17-25 x 20-50 pm; conidiophores macronemarous, up
ro zuu um long . H. t'tscosporum
9. Conidia filament 5-6 um, loosely coiled 4-{ times, with 10-18 septa per coil, conidia oval, 3o-42x22-3o gm; conidiophores
micronematous,s-l2o pm long .H. pluriseptafum
Helicoon gigantisporum and amended key to the genus
conidia coil in a clockwise direction as illustrated in the
scanning electron micrographs of Aa & Samson ('199a). In
Table 1, a summary of the differences between the two species
is given. Two other species, namely H. pluriseptatwmBeverw.
(van Beverwijk, 7954) and H. sessile Morgan (1,892), oc-
casionally produce conidiophores shorter than 14 um.
However, the conidia in these two species are very much
smaller than those of H. gigantisporum.
For descriptions of H. auratum (Ellis) Morgan (1892), H.
chlamydosporwra Abdullah & J. Webster (19s0), H. ellipticum
(Peck) Morgan (1892), H. farinosum Linder (1929), H.
fwscosporum Linder (I92il, and H. richonis (Boud.) Linder
(7929), the readers should refer to the individual papers or
Goos ef al. (79s6). A key to the 10 accepted species of Helicoon
amended from Goos et al. (7986) and Aa & Samson (199a) is
presented here.
We would like to thank Ms Helen Leung for technical
assistance and Mr A. Y. P. Lee for photographic assistance.
(Accepted 29 March 1996)
1,488
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Three species of Xenosporium producing ellipsoidal or ovoid conidia were collected from decaying culms of Miscanthus floridulus submerged in freshwater streams of Alishan area, Chiayi County, Taiwan. Xenosporium formosiforme and X. parvulum are described and illustrated as new species. Xenosporium africanum is described in this paper as a new record for Taiwan. The phylogenetic relationships of Xenosporium species and related taxa were sought by comparing the sequences of their internal transcribed spacer (ITS) barcode, 28S rDNA, and RNA polymerase II second largest subunit (RPB2) gene segments. Phylogenetic analysis of these Xenosporium species supports their placement in the Tubeufiaceae. A synopsis of Xenosporium species producing ellipsoidal or ovoid conidia is given. The criteria used to differentiate species are discussed.
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Freshwater Dothideomycetes
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Full-text available
  • Dec 2020
Freshwater Dothideomycetes are a highly diverse group of fungi, which are mostly saprobic in freshwater habitats worldwide. They are important decomposers of submerged woody debris and leaves in water. In this paper, we outline the genera of freshwater Dothideomycetes with notes and keys to species. Based on multigene analyses and morphology, we introduce nine new genera, viz . Aquimassariosphaeria , Aquatospora , Aquihelicascus , Fusiformiseptata , Neohelicascus , Neojahnula , Pseudojahnula , Purpureofaciens , Submersispora ; 33 new species, viz . Acrocalymma bipolare , Aquimassariosphaeria kunmingensis , Aquatospora cylindrica , Aquihelicascus songkhlaensis , A. yunnanensis , Ascagilis submersa , A. thailandensis , Bambusicola aquatica , Caryospora submersa , Dictyocheirospora thailandica , Fusiformiseptata crocea , Helicosporium thailandense , Hongkongmyces aquaticus , Lentistoma aquaticum , Lentithecium kunmingense , Lindgomyces aquaticus , Longipedicellata aquatica , Neohelicascus submersus , Neohelicomyces dehongensis , N. thailandicus , Neohelicosporium submersum , Nigrograna aquatica , Occultibambusa kunmingensis , Parabambusicola aquatica , Pseudoasteromassaria aquatica , Pseudoastrosphaeriella aquatica , Pseudoxylomyces aquaticus , Purpureofaciens aquatica , Roussoella aquatica , Shrungabeeja aquatica , Submersispora variabilis , Tetraploa puzheheiensis , T. yunnanensis ; 16 new combinations, viz. Aquimassariosphaeria typhicola , Aquihelicascus thalassioideus , Ascagilis guttulaspora , A. queenslandica , A. seychellensis , A. sunyatsenii , Ernakulamia xishuangbannaensis , Neohelicascus aquaticus , N. chiangraiensis , N. egyptiacus , N. elaterascus , N. gallicus , N. unilocularis , N. uniseptatus , Neojahnula australiensis , Pseudojahnula potamophila ; 17 new geographical and habitat records, viz. Aliquandostipite khaoyaiensis , Aquastroma magniostiolata , Caryospora aquatica , C. quercus , Dendryphiella vinosa , Ernakulamia cochinensis , Fissuroma neoaggregatum , Helicotruncatum palmigenum , Jahnula rostrata , Neoroussoella bambusae , N. leucaenae , Occultibambusa pustula , Paramonodictys solitarius , Pleopunctum pseudoellipsoideum , Pseudocapulatispora longiappendiculata , Seriascoma didymosporum , Shrungabeeja vadirajensis and ten new collections from China and Thailand, viz. Amniculicola guttulata , Aquaphila albicans , Berkleasmium latisporum , Clohesyomyces aquaticus , Dictyocheirospora rotunda , Flabellascoma fusiforme , Pseudoastrosphaeriella bambusae , Pseudoxylomyces elegans , Tubeufia aquatica and T. cylindrothecia . Dendryphiella phitsanulokensis and Tubeufia roseohelicospora are synonymized with D. vinosa and T. tectonae , respectively. Six orders, 43 families and 145 genera which belong to freshwater Dothideomycetes are reviewed. Of these, 46 genera occur exclusively in freshwater habitats. A world map illustrates the distribution of freshwater Dothideomycetes.
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Pseudoclathrosphaerina evamariae gen. et sp. nov. and Sympodioclathra globosa gen. et sp. nov., two aeroaquatic fungi similar to Clathrosphaerina
Article
  • Nov 1997
Pseudoclathrosphaerina evamariae and Sympodioclathra globosa are described and illustrated as new genera and species, respectively. Their features are outlined and compared to similar genera, especially to Clathrosphaerina. The ecological niche as members of the aeroaquatic fungi is discussed and their distribution recorded.
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A new species of Helicoon from Mallorca, Spain
Article
  • Sep 1998
A new aeroaquatic helicosporous hyphomycete, Helicoon maioricensis, from submerged decaying leaves in a small oligotrophic pond in an evergreen oak woodland in Mallorca, Spain is described and illustrated with scanning electron micrographs. The new species forms conspicuous colonies with much branched and minutely roughened anastomosing hyphae both in vivo and in vitro as well as dark fuscous to black subglobose conidia that are borne singly on short conidiophores. The new species is compared with H. pluriseptatum. A dichotomous and a synoptic key to the 16 species in the genus are provided.
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The anamorph genus Helicoon
Article
A monograph is provided of the anamorph genus Helicodendron, with keys to and illustrations of all described species.
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On Helicodendron tubulosum and some similar species
Article
The history and literature of Helicodendron tubulosum (Riess) Linder is surveyed. A number of species of Helicodendron, which resemble more or less closely one or other of the descriptions of H. tubulosum, have been isolated from leaves decaying in static water. None of these isolates will produce spores under water, but spores are usually formed freely when the substrate on which the fungus is growing is exposed to a moist atmosphere in the light. These isolates are described under the following names: H. tubulosum (Riess) Linder, H. conglomeratum sp.nov., H. articulatum sp.nov. and H. luteo-album sp.nov. The very common H. triglitziensis (Jaap) Linder is also briefly considered.
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Helicodendron giganteum n sp., and other aerial sporing Hyphomycetes of submerged leaves
Article
The fungus flora of leaves decaying at the bottom of ponds and lakes, where the water is more or less static, is made up largely of Hyphomycetes (mostly helico-sporous) which sporulate only when the leaves are exposed to air. A number of these fungi have been grown in pure culture, and five have been identified as Helicoon fuscosporum Linder, Helicodendron tubulosum (Riess) Linder, H. triglitziensis (Jaap) Linder, H. hyalinum Linder; and Clathrosphaera spirifera Zalewski. Helicodendron giganteum n.sp. is described in detail.
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A new species of Helicoon
Article
Helicoon macrosporum sp. nov. is described and illustrated from wood collected in Kristiansminde, Denmark and compared with related taxa.
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North American Helicosporae. Cincinnati Society of Natural History
  • Jan 1892
  • 39-52
  • A P Morgan
Morgan, A.P. (1892). North American Helicosporae. Cincinnati Society of Natural History ]oumal 15, 39-52.
Occunence of aero-aquatic fungi in soil. lransa(ilons ol tne bnt$n lvtvcotoStcat Joctery /r
  • Jan 1980
  • S K Abdullah
  • J Webster
Abdullah, S. K. & Webster, J. (1980). Occunence of aero-aquatic fungi in soil. lransa(ilons ol tne bnt$n lvtvcotoStcat Joctery /r, 5 l r-J14.
North American Helicosporae
  • Jan 1892
  • 39
  • Morgan