Botanical Journal 01” the Linnean Society, 75: 195-209. With 2 plates and 2 figures
September 1977
Three new genera of lichenicolous fungi
D. L. HAWKSWORTH, F.L.S.
Commonwealth Mycological Institute, Kew, Surrey TW9 3AF
Accepted for publication June 1977
Three new genera of fungi occurring on lichens are described and illustrated. Clypeococcum D.
Hawksworth (Pleosporales) is introduced for th e species previously treated as Phaeodothis
cladonema (Wrdd.) Theiss. & Syd, which occurs in thalli of Cetrelia olivetorum sensu lato and
Parmelia verruculifera. Doratomyces phillipsii, a species hitherto not recognized as
lichenicolous, occurs o n Steinia geophana and Thrombium epigaeum, both of which have
Leptosiru as the algal partner; this fungus is sufficiently different from other Doratomyces
species t o justify the new genus Leightoniomyces D. Hawksworth & Sutton (Dematiaceae).
Refractohilum D. Hawksworth (Moniliaceae) is introduced for three species: Sporidesmium
achromaticum Sutton (on Parmelia aff. sulcata and wood), R. galligenum sp. nov. (forming galls
on Nephroma laevigurum), and Ovularia peltigerae Keissl. (forming galls on Peltigera species).
KEY WORDS:-Taxonomy-lichenicolous
fungi-Pleosporales-Hyphomycetes-lichens-Clypeococcum-Leigh toniomyces-Refractohilum.
CONTENTS
Introduction
. . . . . . . . . . . . . . . . . . . . . .
Clypeococcum gen. nov.
Leightoniomyces gen. nov.
Refractohilum gen. nov.
Acknowledgements
. .
References
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196
199
204
209
209
INTRODUCTION
Lichenicolous fungi (fungi obligately occurring on lichens), have received
scant attention in the British Isles since the pioneering studies of Lindsay
(1857, 1869, 1871) apart from the few taxa discussed by Smith (1910, 1926)
and the check-list of Watson (1948). Some lichenicolous fungi cause little or no
visible damage t o their hosts and may even be regarded as parasymbiotic (i.e.
symbiotic with a pre-existing symbiosis; see Hawksworth, in press, a), but other
lichenicolous fungi can cause gall-like deformations, necrosis, or even death of
the host. In irecent years some attempt has been made to improve our
knowledge of lichenicolous fungi in the British Isles (Hawksworth, 1975a,
195
196
D. L.
HAWKSWORTH
1975b, 1976, 1977, in press b, Hawksworth & Punithalingham, 1973) and the
present contribution represents a continuation of these investigations.
Clypeococcum D. Hawksworth, gen. nov.
TYPUS. Lecidea cladonema Wedd.
DERIVATIO. Clypeo- (from Latin clypeus, a round brazen Roman shield;
recalling the shield-like stromatic growth over the pseudothecia) -coccum
(from Greek K ~ K K O Cand Latin coccus, minute round grains or seeds; recalling
the generic name Polycoccum Saut. ex Korb, to which Clypeococcum is allied).
Fungus lichenicola ad familia Pleosporaceae Wint. (Ascomycotina-Loculoascomycetes-Pleosporales) pertinens. Pseudothecia globosa, nigra, ostiolata,
non distincte rostrata, numerosa, in clypeo aggregata. Pseudoparaphyses
distinctae, filiformes, sparse ramosae et anastomosantes. Asci subcylindrici,
bitunicati, octospori. Ascosporae ellipsoideae, uniseptatae, atrobrunneae, cum
muris levitissimo-verruculosis.
Fungus lichenicolous, belonging to the family Pleosporaceae Wint. (Ascomycotina-Loculoascomycetes-Pleosporales). Pseudothecia globose, ostiolate,
not distinctly beaked, black, numerous and united in groups by a common
black clypeus. Pseudoparaphyses remaining distinct, filiform, hyaline, septate,
sparsely branched and anastomosing. Asci subcylindrical, short-stalked,
bitunicate, with a distinct internal apical beak, eight-spored. Ascospores
ellipsoid, uniseptate, dark brown, with delicately verruculose walls.
This new genus is introduced for the single species originally described as
Cecidea cladonema Wedd. and treated as Phaeodothis cladonema (Wedd.)
Theiss. & Syd. by more recent authors (e.g. Keissler, 1930; Santesson, 1960;
Clauzade & ROUX,1976). However, the generic name Phaeodothis Syd. has to
be rejected as a nomen c m f u s u m as its type species was based on discordant
elements (Santesson, 1960).
The superficial appearance of Clypeococcum cladonema (Wedd. )
D. Hawksw. is strongly reminiscent of Homostegia piggotii (Berk. & Br.) Karst.
which also forms blackened, stromatic patches on its hosts; that species differs
from C cladonema in that the pseudothecia occur as loculi in a dense, stromatal
tissue which involves little host tissue and which encloses the whole of the
pseudothecia, not merely uniting them in their uppermost parts. Furthermore,
the ascospores are always 3-septate, elongate-ellipsoid, and entirely smoothwalled. The shape and size of the ascospores, their ornamentation, and the
anastomosing pseudoparaphyses of Clypeococcum are all features encountered
in Polycoccum Saut. ex Kbrb. (of which Didymosphaeria Fuckel is almost
certainly a synonym), which includes many lichenicolous fungi, and Microthelia Korb. However, in both these genera the pseudothecia are quite discrete
and not united in either a stroma or clypeus. In view of the development of a
distinct clypeus, which in this instance involves both the cells of the upper
cortex of the host as well as the hyphae of the invading fungus, and the
considerable taxonomic weight accorded to this character in this group of fungi
(e.g. v. Arx & Miiller, 1975), it is evident that a new genus has to be erected for
Lecidea cladonema Wedd.
NEW GENERA OF LICHENICOLOUS FUNGI
197
Clypeococcurn cladonema (Weddell) D. Hawksworth, comb. nov.
Lecidea cladonema Wedd., Bulletin de la Sociktk botanique de France, 21: 345
(1874).
Abrothallus cladonema (Wedd.) Zopf, Hedwigia, 35: 344 (1896).
Buellia cladonema (Wedd.) O h . , Bulletin de 1 'AcadCmie Internationale de
Gkographie Botanique, 15: 282 (1905).
Dothidea cladonema (Wedd.) Vouaux, Bulletin de la Sociktk mycologique de
France, 28: 195 (1912).
Phaeodothis cladonema (Wedd.) Theiss. & Syd., Annales mycologici, 13: 597
(1915).
ICONES. Fig. 1 A-D.
TYPUS. 26: iv: 1874, herb. H.-A. Weddell, holotype PC!, isotype S n.v.
LOCUS. France, Hkrault, 1'Agde.
HOSPIS. On thalli of Parmelia verruculifera Nyl. on volcanic rocks.
Pseudothecia globose to subglobose, ostiolate, not distinctly beaked,
aggregated into groups of 10-20 united by a common clypeus, black, immersed,
mainly 60-150 pm diam; clypeus forming a rounded, black and slightly raised
patch on the surface of the host lichen to 1.5 mm diam, composed of a
mixture of host tissues and hyphae of the fungus, mainly 20-40pm thick;
pseudothecial walls composed of brown to dark brown pigmented cells, textura
intricata-like when young but becoming pseudoparanchymatous at maturity,
variable in thickness, mainly 15-25 pm thick, individual cells mainly 3-5 pm
diam. Pseudoparaphyses distinct, persistent, filiform, hyaline, septate, sparsely
branched and anastomosing, 2.5-3.5 pm wide. Asci subcylindrical, shortstalked, bitunicate, with a distinct internal apical beak, mainly
60-70 x 10-14pm, 8-spored. Ascospores distichously arranged in the asci,
ellipsoid with rounded apices, l-septate, the septum occurring below the centre
of the spore, somewhat constricted at the septum, dark brown, walls disctinctly
minutely verruculose, (13.5-)14-16(-18) x (5.5-)6-7(-7.5) pm.
This fungus was originally reported as occurring on the thallus of Parmelia
delisei (Duby)Nyl., but, as noted by Santesson (1960), the type host is not that
species. Santesson referred the host to P. isidiotyla Nyl. but, since that time,
this group of lichens has been revised taxonomically and the type host is now
correctly named P. verruculifera Nyl. On this host the fungus occurs as rounded
black patches and appears to cause little damage. Santesson (1960) reported
this species from both Norway and Spain on the basis of material growing on
thalli of Cetrelia olivetorum (Ach.) Culb. & C. Culb. sensu lato (syn. Parmelia
cetrarioides (Duby) Nyl.) and it was its recent discovery on this same host in
Scotland which prompted the present investigation of its taxonomy. In the
Scottish material the infected tissue eventually splits from the host thallus,
falling away to leave a neat, rounded hole; adjacent areas of the thallus do not
appear to be adversely affected by the presence of this fungus as they remain
their normal grey colour.
Keissler (1930) indicated that Lecidea badiella Nyl. might be a synonym of
the present species, although in the same work he also listed that epithet as a
synonym of Karschia bayrhofferi (Schaer.) Rehm; an examination of the
holotype of Nylander's taxon (Pyrenees orientalis, F o r p Real, on Parmelia
198
D.
L.
HAWKSWORTH
B
H
10Gm
Figure 1. Clypeococcum cladonema from the holotype (PC). A, Vertical section of pseudothecia and clypeus; B, pseudoparaphyses; C, asci; D, ascospores.
NEW GENERA O F LICHENICOLOUS
FUNGI
199
verruculifera thalli, 16: vii: 1872, W. Nylander, H-Nyl. 10395!) showed that his
latter treatment: was correct.
Additional specimen examined: BRITISH ISLES, Scotland, Argyllshire, Seil
Ballachuan, wood south of Port Mor, on Cetrelia olivetorum sensu Zato thallus,
30: vi: 1976, B. J. Coppins 2579 (IMI 212821).
Leightoniomyces D. Hawksworth & Sutton, gen. nov.
TYPUS. Periconia phillipsii Berk. & Leight.
DERIVATIO. Leightonio- (from the surname of the Rev. William Allport
Leighton F.L. S., 1805-1889, a leading British lichenologist and collector and
co-author of the type species of the genus; see Hawksworth & Seaward, 1977,
mykes,
,
for further information of Leighton)-myces from Greek p i ) ~ q ~
fungus).
Fungus lichenicola vel algicola ad Hyphomycetes familia Dematiaceae Fr.
sensu lato pertinens. Coloniae effusae, nigrae; mycelium immersum; stroma,
setae et hyphopodia desunt. Conidiophora macronemata, synnemata, atrobrunnea vel nigra, apices expansa et capituliformia. Cellulae conidiogenae
holoblasticae, annellidicae, terminaliter integratae vel determinatae, ampulliformes, brunneae, cum muris levibus ad conspicue rugosis et crassis. Conidia
singularia producta, non-catenata, sicca, acrogena, globosa, non-truncata,
non-septata, atrobrunnea, grosse verrucosa, cum cicatrice simili uno poro
hyalino.
Fungus lichenicolous or algicolous, belonging to the family Dematiaceae Fr.
sensu lato (Deuteromycotina-Hyphomycetes).
Colonies effuse, black;
mycelium immersed; stroma, setae and hyphopodia absent. Conidiophores
macronematous, synnematous, dark brown or black, expanded and capitate at
the apices of the synnemata. Conidiogenous cells holoblastic, annellidic,
terminally integrated or discrete, ampulliform, brown, with smooth to
conspicuously roughened and thick walls. Conidia produced singly, not in
chains, dry, acrogenous, globose, not truncate, not septate, dark brown,
coarsely verrucose, with an attachment scar resembling a hyaline pore.
This new genus is described here to accommodate the species originally
described as Periconia phillipsii Berk. & Leight. The genus Doratomyces Corda
was employed for this fungus by Morton & Smith (1963); in that genus the
conidiogenous cells clearly proliferate percurrently but the conidia are
smooth-walled (except in D. nanus (Ehrenb. ex Link) Morton & G. Sm.),
catenate, paler, and with a distinctly truncate base. Memnoniella Hohn. also
shows some superficial similarity to Leightoniomyces but in that genus
synnemata are unknown (except in M . stilboidea (Munjal & Kapoor) M. B.
Ellis), the conidia are echinulate rather than coarsely verruculose, catenate, and
the conidiogenous cells, which are monophialidic and not annellidic, arise in a
single group a t the apex of the conidiophores. Neither Doratomyces nor
Memnoniella is known to include any lichenicolous or algicolous species. In
Xanthoriicola I>.Hawksworth. (see Hawksworth&Punithalingam, 19731,theonly
other genus of lichenicolous dematiaceous hyphomycetes known which
I"
200
D.
L. HAWKSWORTH
produces non-septate rough-walled conidia, the conidiogenous cells are monophialidic and very broad at the apex, the conidia have a more delicate
ornamentation; and synnemata are unknown.
Annellides in hyphomycetes have been the subject of several studies using
the electron microscope, (Cole & Aldrich, 1971; Hammill, 1971; Kiffer,
Mangenot & Reisinger, 1971). In Scopulariopsis Bain., both Hammill (1971)
and Cole & Aldrich (1971) described a septal pore at the base of the conidium
and in Doratornyces, which is the synnematal analogue of Scopulariopsis,
Hammill (1972) and Kiffer et al. (1971) demonstrated a similar situation.
Leightoniornyces provides no exception to this as a pore is readily visible even
in mature conidia by light as well as scanning electron microscopy (Plate 2 B-C)
but, whereas in Scopulariopis and Doratomyces the base of the conidium is
comparatively wide in relation to the whole conidium width (0.75 :1), in
Leightoniomyces it is much narrower (<0.25 : 1). Furthermore, almost the
whole of the basal conidial scar in Leightoniomyces is occupied by the pore.
The difference in conidiogenesis seen between Leightoniomyces and Doratomyces and Scopulariopsis is consequently rather one of degree than of a
fundamental difference in conidiogenesis.
Stachybotrys Corda, which produces solitary conidia from monophialides,
also shows some superficial similarity to Leightoniornyces. Although the EM
evidence for the presence of a septal pore in phialosporic conidia is disputed,
Campbell (1972) demonstrated that in S. atra Corda, though a pore is evident
during the formation of the conidium, it becomes plugged during maturation
and is not evident in the mature conidium. Stachybotrys is closely allied to
Memnoniella, referred to above, differing primarily in that the conidia are not
catenate but formed in slimy heads.
There is unfortunately no direct SEM evidence concerning the nature of
spore ornamentation in Doratomyces and Scopulariopsis to enable a meaningful comparison with Leightoniornyces to be made, although Cole & Aldrich
(1971) described in detail the orientation of rodlet structures in the walls of
developing conidia of S. brevicaulis (Sacc.) Bain.
Leightoniomyces is consequently recognized as a new genus on the basis of
the conidial shape and scar, the solitary production of conidia, the annellidic
conidiogenous cells (which also tend to become verrucose, a character not
recorded in any of the other genera mentioned above), and, to a lesser extent,
the ornamentation of the conidia, production of synnemata, and the
algicolous/lichenicolous habit.
Leightoniomyces phillipsii (Berk. & Leight.) D. Hawksworth & Sutton,
comb. nov.
Periconia philli~siiBerk. & Leight., Annals and Magazine of Natural History
(series IV), 15: 3 3 (1875).
Sporocybe phillipsii (Berk. & Leight.) Sacc., Sylloge fungorum, 4: 609 (1886).
Stysanus phillipsii (Berk. & Leight.) Mason & M. B. Ellis, Mycological Papers,
56: 40 (1953).
Cephalotrichum phillipsii (Berk. & Leight.) Hughes, Canadian Journal of
Botany, 36: 744 (1958).
NEW GENERA OF LICHENICOLOUS FUNGI
201
Doratomyces phillipsii (Berk. & Leight.) Morton & G . Sm., Mycological Papers,
86; 82 (1963).
ICONES. Plates 1 A-F and 2 A-C. Mason & Ellis, Mycological Papers, 56: 40,
fig. 5 (1953); Morton & Smith, Mycological Papers, 86: 82, fig. 28 (1963);
Ellis, Dematiaceous Hyphomycetes: 330, fig. 226D (1971).
TYPUS. v: 1874. W. A. Leighton, holotype K!, isotypes Cooke, Fungi
Britannici Exsiccati, Ed. 2, no. 166 K! (8 packets).
LOCUS. British Isles, Wales Caernarvonshire, Trefriw.
HOSPIS. On Thrombium epigaeum (Pers.) Wallr. on earth.
Mycelium immersed, becoming superficial only with the formation of
synnemata, pale brown to almost hyaline, hyphae mainly 2-3 pm wide.
Synnemata erect, rigid, black, 100-200(-250) pm tall, stipe 25-60 ,urn wide for
most of its length, abruptly expanded above into a black globose mass of
conidiogenous cells and conidia mainly 150-200 pm diam; stipe composed of
vertically to somewhat spirally orientated, compacted, septate, brown to dark
brown, smooth to slightly roughened hyphae mainly 1.5-2.5 pm wide.
Conidiogenous cells holoblastic, annellidic, integrated, terminal or discrete,
arising only at the apices of the synnemata, densely crowded, ampulliform,
with up to 4 percurrent proliferations, brown, mainly rough-walled, thickwalled, (7-)lo-14(-17) pm tall, swollen to 5-7 pm wide basally or centrally
and tapering (often abruptly) to 2-4 pm wide at the apex. Conidia arising singly
at the apices of the conidiogenous cells, dry, adhering in a dense, globose head,
not catenate, globose, non-septate, dark brown to almost black, walls
extremely coarsely verrucose, individual verrucae angular, often 2-4 pm diam,
wall thickened around the point of fomer attachment which has a persistant
hyaline pore-like scar c. 1 pm diam, (8-)9-12(-14) pm.
This fungus, hitherto known only from Leighton’s original collections made
in 1874, was irediscovered in 1975 by Mr P. W. James growing on the lichen
Thrombium epigaeum (Pers.) Wallr. In April 1977 he made a second collection
of the same fungus in the Azores where it was growing on Steinia geophana
(Nyl.) Stein (syn. Lecidea geophana Nyl.). Since its original description,
Leightoniomyces phillipsii has consistently been regarded as growing on soil
alone. Its re-discovery associated with lichens prompted an investigation into
the actual substrate of the 1874 collection and perithecia of Thrombium
epigaeum were found to be present in this also. In the case of both the
collections on Thrombium, perithecia are sparse and cells of the phycobiont
(algal partner), Leptosira thrombii Tsch.-Woess, apparently predominate. As
the algal cells age in the herbarium they become decolourized rendering them
easily overlooked, only soil particles being readily visible without microscopic
examination. It is consequently not surprising that the association of this
fungus with an alga or lichen had previously been overlooked, particularly as
the perithecia that are present are largely immersed.
The recent discovery of Leightoniomyces on a second host, Steinia
geophana, which is an apotheciate taxon quite remote from the pyrenocarpous
Thro.wbium, was of particular interest as this lichen not only occurs in rather
similar habitats to T. epigaeum but also appears to have a species of Leptosira
as its algal partner. In view of the algal host being similar and the scant
202
D. L.
HAWKSWOKTH
Plate 1. Leightoniomyces phillipsii from IMI 198438. A, Habit, x50; B, vertical section of
synnema and head, x350; C, conidiogenous cells (annellides), x1400; D, conidia (the lower
three in optical section), x1400; E, vertical section of head from which the conidia have been
removed to show the arrangement of the conidiogenous cells, x900; F, hyphae of the stalk of
the synnema, vertically arranged, x3 500.
perithecia in the Thrombiurn collections it is possible that this fungus is
essentially algicolous rather than lichenicolous.
Despite the disparate hosts and geographical locations, the Leightoniomyces
fungi on both hosts are clearly conspecific. The only difference noted was that
while in the collections on Thrombiurn it was difficult to see more than one
annellation on the conidiogenous cells, in that on Steinia up to four were
NEW GENERA O F LICHENICOLOUS FUNGI
20 3
Plate 2. Leighrtoniomyces phillipsii from IMI 198438, scanning electron micrographs. A, Base of
head showing vertically orientated hyphae in the synnema, attached conidia, and apex of a
conidiogenous cell (arrow), x3000; B, conidium showing the prominent pore-like scar (arrow),
x3000; C, conidia, the upper showing the pore-like scar (white arrow) and the lower h septa1
plug over this scar (black arrow; presumably the first conidium to be formed from a
conidiogenous cell), x3000.
regularly clearly distinguishable by light microscopy. As the number of
annellations found is to be expected to increase with the age of the fungus, this
observation would not appear to be taxonomically important. It is quite
feasible that this difference may be partly due to the thalli of S. geophana
being somewhat less ephemeral than those of T. epigaeum.
Additional specimens examined: BRITISH ISLES, England, Herefordshire,
Ross-on-Wye, Dove’s Nest, Howle Hill, on Thvombium epigaeum on a shaded
earth bank, v: 1975, P. W. James (IMI 198438). SPAIN, Azores. S2o Miguel,
Lagoa do Fago, near Barrosa, alt. c. 900 m, on Steinia geophana on soil
recently cut on roadside bank by a new road, with Gyalidea hyalinescens (Nyl.)
Vezda, 6 : iv: 11977, P. W.James (IMI 214047).
204
D.
L.
HAWKSWORTH
Refractohilum D. Hawksworth, gen. nov.
TYPUS. Refractohilum galligenum D. Hawksworth.
DERIVATIO. Refracto- (from Latin refractus from refringo, to break apart)
-hilurn (from Latin hilum a trifle, used in mycology to denote a mark or scar
at the point of former attachment of a spore to a sporophore). The name
recalls the refractive basal part of the conidia seen in all species included here.
Fungus lichenicola ad Hyphomycetes familia Moniliaceae Dumort. sensu lato
pertinens. Coloniae effusae vel diffusae, hyalinae, pilosae; mycelium maximum
partim immersum in hospite. Conidiophora macronemata, mononemata, erecta,
non ramosa, cylindrica, hyalina, laevia, pariibus crassis. Cellulae conidiogenae
monoblasticae, in conidiophora incorporatae, terminales, percurrentes, cum
annellationibus terminalibus distinctis. Conidia singularia producta, noncatenata, sicca, primo in apice conidiophori et dein proliferationibus successivis
oriunda, cymbiformia, laevia, hyalina, 0-3 septata, guttulata, apice obtusa, basi
truncata, crassa et refracta.
Fungus lichenicolous, belonging to the family Moniliaceae Dumort. s e n m
lato (Deuteromycotina-Hyphomycetes). Colonies effuse or diffuse, hyaline,
hair-like; mycelium mainly immersed in the host but persisting on the substrate
of the host after the death of the host in one species. Conidiophores
macronematous, mononematous, erect, unbranched, cylindrical, sparsely
septate, hyaline, smooth- and thick-walled. Conidiogenous cells monoblastic,
incorporated into the conidiophores, terminal, percurrently proliferating with
distinct terminal annellations. Conidia arising singly, dry, not catenate, the first
arising from the apex of the conidiophore and the subsequent ones by
successive proliferations, cymbiform, smooth-walled, hyaline, 0-3 septate,
guttulate, apex obtuse, base distinctly truncate, thick and refractive.
R efractohilum is introduced here for three species: Ovularia peltigerae
Keissl., Sporidesmium achromaticum Sutton, and a fungus forming galls on
Nephroma laevigatum Ach. recently collected in Devonshire. These three fungi
are all characterized by hyaline, thick-walled and unbranched conidiophores,
percurrently proliferating (annellidic) conidiogenous cells, and cymbiform
conidia which have a very characteristic highly refractive truncate base. The
genus Ovularia Sacc. (type species 0. obliqua (Cooke) Sacc.) is quite
inappropriate as in that genus the conidia are borne on denticles and not
produced by annellides. Sutton (1973) placed his species in Sporidesmium Link
ex Fr. (type species S. atrum Link) tentatively because it was entirely hyaline
and not pigmented as is usual in that genus. In addition to the difference in
pigmentation, R efractohilum differs from Sporidesmium in the refractive bases
of the conidia as well as in the primarily lichenicolous habit.
The thick-walled erect and hyaline conidiophores are somewhat reminiscent
of Monocillium Saksena but in that genus the conidiogenous cells are
monophialidic and so do not show regular annellations, and the conidia are
often catenate, much smaller, and lack the distinctive cymbiform shape and
refractive basal area seen in Refractohilum.
The three species placed in Refractohilum here form a cohesive group which
appears t o occupy a rather isolated position amongst other moniliaceous
NEW GENERA OF LICHENICOLOUS FUNGI
20 5
hyphomycetes. They may be separated from each other according to the
following key.
Key to the species of Refractohilum
1. Conidia consistently simple, forming gaIls on Nephroma or Peltigera.
1: Conidia 3-septate when mature, on Parmelia aff. sulcata (thallus) and
. .2
wood on which the lichen was formerly present, not forming galls
. . . . . . . . . . . . . . . . . . . . . . . R. achromaticurn
2. Conidia (8-19-11(-14) x 3-3.5(-4) pm; forminggalls on Nephroma
laevigatum . . . . . . . . . . . . . . . . . . . R. galligenum
21 Conidia (15-)18-20(-25) x 6-7.5(-9) pm; forming galls on Peltigera
species . . . . . . . . . . . . . . . . . . . .
R.peltigerae
Refractohilum achromaticum (Sutton) D. Hawksworth,
comb. nov.
Sporidesmiurn achromaticum Sutton, Mycological Papers, 132: 105 (1973).
ICONES. Fig. 2A. Sutton, Mycological Papers, 132: 106, fig. 50 (1973).
TYPUS. 10: vii: 1969, W. Crawford, holotype IMI 144511!, isotype CFB
(=WINF(M) 11752) n.v.
LOCUS. Canada, Manitoba, Red Sucker Lake.
HOSPIS. On Parmelia aff. sulcata Tayl. on Fraxinus and on Fraxinus wood.
Colonies effuse, hyaline, arising from the surface of the host lichen or
persisting on bark or wood after its death. Conidiophores erect, unbranched,
straight or somewhat bent, cylindrical, hyaline, smooth- and thick-walled, 1-5
septate, to 5 0 pm tall and mainly 4-5 pm wide. Conidiogenous cells percurrently proliferating with 1-7 distinct annellations, hyaline. Conidia cymbiform. smooth-walled hyaline, 3-septate when mature, often guaulate, apex
obtuse, base truncate, thickened and highly refractive, (11-)13-15(+17) x
3.5-4.5(-6)
~LITI.
In describing Sporidesmiurn achromaticurn, Sutton (1973) cited about 35
collections from Manitoba and Saskatchewan (these now distributed between
CFB and IMI) and noted that it could occur ". . . over effete ascomycetes,
lichens and along the raised edges of old bark". Examination of the material
now in IMI strongly suggests that this fungus is primarily a parasite of a
Parmelia species (probably P. sulcata Tayl. but too fragmentary for certain
determination) and from the cortex of which, the conidiophores of the fungus
arise. The lobes of the host thallus become discoloured and slightly pustulate,
though not forming massive galls as seen in the other two species of
Refractohilum recognized here, and the host appears to be killed. Following
the death of the host, the fungus appears to be abIe to persist saprophytically
on the wood or bark formerly covered by its host. On many of the collections
in which no lolbes of the host remain, broken rhizinae without thalli are present
and it is in such specimens that the effete ascomycetes occur (perhaps effete
even prior to lichen colonization).
206
D. L. HAWKSWORTH
B
U
M
10pm
Figure 2. Refractohilum species. A, R. achromcnticum from IMI 144844; B, R. galligenum from
the holotype (IMI 212682); C, R . peltigerae from the holotype slides (W 19[?] 16 no. 18892).
The upper row of drawings shows conidiophores with attached conidia and annellations while
the lower shows conidia (the highly refractive bases drawn as black).
NEW GENERA O F LICHENICOLOUS FUNGI
207
Additional specimens examined: CANADA, Manitoba, Saskatchewan, specimens cited by Sutton (1973) now in IMI whose paper should be consulted for
full collection data.
Refractohilum galligenum D . Hawksworth, sp. nov.
ICONES. Fig. 2B.
TYPUS. 1: iv: 1977, D. L. Hawksworth 4427, holotype IMI 212682.
LOCUS. British Isles, England, North Devonshire, Parkham Parish,
Pep per combe.
HOSPIS. On thallus of Nephroma laevigatum Ach. on Quercus in oak
scrub woodland on steep north-facing sea cliffs.
DERIVATIO. Galli- (from Latin gulla, an oak apple or gall) g e n u m (from
Latin suffix -gc’nus, born or produced). The name recalls the ability of the
fungus to produce galls on its host.
Coloniae effusae, hyalinae; mycelium maximum partim immersum in thallo
hospitis, ex hyphis ramosis, septatis, hyalinis, laevibus compositum, usque
3-4 pm latis. Conidiophora erecta, non ramosa, recta vel leviter flexuosa,
cylindrica, hyalina, Iaevia, sparse septata vel simplicia, pariibus crassis, usque
20-30 pm alta (rarissimo ad 4 0 pm aka) et 3-4 pm lata. Cellulae conidiogenae
percurrentes, cum 1-8 annellationibus terminalibus distinctis, hyalinae. Conidia
cymbiformia, interdum irregulariter, laevia, hyalina, non septata, guttulata,
apice obtusa, basi truncata, crassa et refracta, (8-)9-11(-14) x 3-3.5(-4’) pm.
Colonies effuse, hyaline; mycelium almost entirely immersed within the
thallus of the host, composed of hyphae which are branched, septate, hyaline,
smooth-wailed,, and mainly 3-4 pm wide. Conidiophores erect, unbranched,
straight to slightly flexed, cylindrical, hyaline, smooth-walled, sparsely septate
or non-septate, thick-walled, mainly 20-30 pm tall (very rarely to 40 pm tall)
.and 3-4 pm wide. Conidiogenous cells percurrently proliferating, with 1-8
distinct terminal annellations easily seen by light microscopy, hyaline. Conidia
cymbiform, sometimes somewhat irregularly so, smooth-walled, hyaline,
non-septate, guttulate, obtuse at the apex and truncate at the base which is
thickened and highly refractive, (8-)9-ll(-14) x 3-3.5(-4) pm.
This previously unrecognized species causes bullate or pustular gall-like
growths 0.5-4 mm wide to be produced from the upper cortex of the host
and which are composed almost entirely of host tissue. Infected thalli
consequently become extremely deformed. Only a single infected specimen was
discovered in the type locality, where the host is abundant, and in this plant the
infected areas assumed an ochre-yellow t o brownish colour; this discolourization, together with the production of deformations, strongly suggests that
Refractohilum galligenunz should be regarded as a parasite of Nephroma
laevigatum. The fungus is easily recognized in the field by the discoloured
gall-like deformations on the usually smooth thallus lobes and the frosted
appearance these have when examined with a hand-lens which is due t o the
erumpent erect conidiophores.
The symptoms produced by this fungus on Nephroma laevigatum are
extremely similar to those which R . peltigerae induces on Peltigera species;
208
D. L. HAWKSWORTH
these two fungi are, however, readily separable on the basis of the shape and
size of the conidia.
Refractohilum peltigerae (Keissl.) D. Hawksworth, comb. nov.
Ovularia peltigerae Keissl., Beihefte z u m botanischen Zentralblatt, 37: 276
(1920).
ICONES. Fig. 2 C. Keissler, Beihefte z u m botanischen Zentralblatt, 37: 276,
pl. 12 fig. 1-2 (1320); Keissler, Kabenhorst’s Kryptogamrn-Flora von Deutschland, Osterreich und der Schweiz, 8: 592, fig. 115, et 593, fig. 116 (1930);
Scholander, Nyt Magazin for Naturvidenskaberne, 73, 34, fig. 7 (1933).
TYPUS. J. Suza, holotype W 19[?] 16 no. 18892! [Slides only.]
LOCUS. Austria, valle ‘Muhlgraben’ in declivi montos Eisenstein prope
Turnitz ad Lilienfeld, alt. c. 600 m.
HOSPIS. On thallus of Peltigeru cf. rufescens (Weiss) Humb. Vide K. von
Keissler, Zoc. cit.).
Colonies effuse, hyaline; mycelium mainly immersed in the thallus of the
host. Conidiophores erect, unbranched, straight or somewhat flexuous,
cylindrical, smooth- and thick-walled, to 6 0 pm tall, 3.5-6 pm wide. Conidiogenous cells percurrently proliferating, with 1-8 distinct terminal annellations
easily seen by light microscopy, hyaline. Conidia obpyriform to cymbiform,
smooth-walled, hyaline, non-septate, sometimes guttulate, obtuse at the apex
and truncate at the base which is thickened and refractive, (15-)18-21(-25) x
6-8(-9) pm.
This fungus was originally reported to occur on Peltigera rufescens but in the
absence of any intact material of the host in W it is impossible to firmly
establish the species of Peltigera from which the slides constituting the
holotype of the fungus came. These slides lack locality data but are in a packet
labelled “novsp.” in Keissler’s handwriting. There are two further collections
of this fungus in W, one of which is on P. rufescens and the other of which is
on a species of Peltigera too fragmentary for certain determination to species
level. It also occurs on P. spuria (Ach.) DC. in Sweden (Scholander, 1933).
Refractohilum peltigerae causes pustulate galls 0.5-5 mm wide to form from
the upper cortex of the host. These galls are reddish brown in colour and
illustrated by Keissler (1930); the original drawings of Keissler are preserved in
W as W 1930 nos. 140-141. When examined with a hand-lens, the erumpent
conidiophores appear as minute whitish hairs over the surface of the galls as do
those of R. galligenum. The details of conidiogenesis in R. peltigerae were
overlooked by Keissler in his descriptions of this fungus but percurrent
proliferation is clearly evident on his original slides.
Refractohilum peltigerae differs from R. galligenum in the shape and size of
the conidia.
Additional specimens examined: CZECHOSLOVAKIA, Mahren, Velk6 Mezirici
(Gr. Meseritsch), bei Netin, on Peltigera sp., vii: 1910, R. Picbauer (W 1932 no.
1840). FINLAND, Fennia Austro-Occidentale, ad oppidum Turku, in mpibus
granit., on Peltigera rufescens, vi. 1926, J. Suza (W 1930 no. 6).
NEW GENERA O F LICHENICOLOUS FUNGI
209
ACKNOWLEDGEMENTS
I am very gr,ateful to Mr P. W. James and Mr B. J. Coppins for sending me
their collections of lichenicolous fungi for study, to Dr B. C. Sutton for his
invaluable assistance over the treatment of Periconia phillipsii, t o the Keepers
and Curators of the herbaria cited in the text who allowed me to examine
material in their care (H, K, PC and W), to Dr T. W. K. Young for taking the
SEM photographs presented here as Plate 2, and lastly to Mr D. W. Fry for his
assistance in the preparation of Plate 1.
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