Trans. Br, mycol. Soc. 77 (3), 475-483 (1981)

[ 475 ]

Printed in Great Britain

TELEOMORPHS OF THREE AQUATIC HYPHOMYCETES

By S. K. ABDULLAH*, E. DESCALS AND J. WEBSTER

Department of Biological Sciences, University of Exeter

The teleomorphs of Tricladium splendens, Articulospora tetracladia and Dimorphosporafoliicola are described and illustrated. They are respectively Hymenoscyphus splendens n.sp.,Hymenos cyphus tetracladius n .sp, and Hymenoscyphus foliicola n.sp .

Webster & Descals (1979, 1981) have listed theknown connexions between 'Ingoldian' aquaticH yphomycete anamorphs and their teleomorphs.The present paper describes three further con-nexions. In most cases, the teleomorphs have beencollected on twigs, leaves and cupules fromstreams and ponds. Single ascospore isolates havebeen prepared by techniques described in Webster& Descals (1979).

In two cases (T ricladium splendens Ingold andDimorphosporafoliicola Tubaki), conidia developeddirectly on the surface of dry 0'1 % malt extractagar cultures, but in Articulospora tetracladia,conidial development only took place when stripsof culture were immersed in water.

Hymenoscyphus splendens sp.nov. (Figs 1-2,3A- C)

Apothecia disseminata, superficialia, eburnea velcremea, siccanteapallide-lutea vel brunnea, cylindrata,0'8-1 '2 mm alta, 0'6-1 '0 mm diam , Hymenium circa100 pm latum. Excipulum medullare textura intricata,ex hyphis intertextis 3-4 pm latis compositum;excipulum externum textura globulosa, ex stratispaucis cellarum, ad 30 pm diam compositum. Cellulaead marginem disci plerumque elongatae in capilloscylindratos laeves, non-ramosos, sparsim septatos ethyalinos. Asci octospori, cylindrati vel clavati, 40-80 x7-10 pm ; porus cyaneusin KI. Ascosporae fusiformes,ellipticae vel inaequilaterales, unicellulae 7-10(-13) x2'5-3'5 pm, supra biseriatae, infra uniseriatae. Para-physes cylindratac, non attingentes ascos, apicibusgranulatis, vix septatae, 2-3 pm latae ,

In cupulis Fagi sy loaticae, Waggoners' Wells, propeHindhead, Surrey, Anglia,mensaeFebruario, 1979,leg.S. K. Abdullah. Specimen IMI 255256typus est.

Te/eomorph (Figs 1, 3A-C): Apothecia scattered,superficial, white to creamy, drying pale yellow tolight brown, cylindrical to funnel-shaped with awide cylindrical base, 0'8-1 '2 mm tall and0'6-1 '0 mm in diam . Hymenium about 100 pmth ick; medullary excipulum of textura intricata,

* Present address: Department of Biology, Collegeof Science, University of Basrah, Basrah, Iraq.

interwoven hyphae 3-4 pm wide; ectal excipulumof textura globosa, composed of a few layers ofisodiametric thin-walled cells, up to 30 pm indiam; cells towards the margin of the disk 'fre-quently elongated into smooth cylindrical blunthairs, unbranched, sparsely septate and hyaline.Asci 8-spored, cylindrical-clavate, 48-80 x 7-10pm, pore staining deep blue in Melzer's reagent.Ascospores fusiform elliptical or inequilateral,r-celled, 7-10(-13) x 2'5-3'5 pm in size, biseriate.above, un iseriate below. Paraphyses cylindrical,not exceeding the asci, with granular apices,scarcely septate, 2'5-3 pm wide.

Specimens examined: Holotype on cupules of Fagussyluatica inoculated with conidia derived from asco-spores. Apothecia originally collected from cupules ofFagus from Waggoners' Wells, Hindhead, Surrey,England, February 1979. S. K. Abdullah. The typespecimen has been deposited as Herb. IMI 255256.Isotypes are preserved in Herb. Exr, No. 3587.

One of us (S.K.A.) collected cupules of beech(Fagus sy luatica L.) from a shallow pond atWaggoners' Wells, Hindhead, Surrey, on 3 Feb-ruary 1979. The cupules were brought to Exeter,rinsed in water, and incubated in a plastic luncheonbox lined with moist blotting paper at 15 °C forthree weeks. Short-stalked, cream-coloured ape-thecia developed on two of the cupules. When theapothecia were ripe, ascospores were projected onto 0'1 % malt extract agar with added 0'008 %Crystamycin, The ascospores germinated over-night and a series of single and multi-spore cul-tures were prepared on further plates of the samemedium and of 2 % malt extract agar . Theseplates were incubated for 7 days at 15° under NUV(phillips Black Light). In all cultures, the charac-teristic conidia of Tricladium splendens Ingold(1942) were observed, developing on aerial coni-diophores (Fig. 1). The identity of these conidiahas kindly been confirmed by Professor C. T.Ingold. Since no type material of this fungus hasbeen designated, these cultures (Herb. Exr. No.3587) are now proposed as lectotype specimens,

476 Te/eomorphs of aquatic hyphomycetes

00~ O O000I

20 11m

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Fig. 1. Hymenoscyphus splendens (Herb. Exr. 3587):(A) V.S. portion of apothecium. (B)Asci,ascosporesand paraphyses.

and have been deposited at the CommonwealthMycological Institute, Herb. 1M!.

In June and September 1979, further col1ec-tions on beech cupules were made from the samelocality. Single and multi-spore cultures from thediscomycete have also produced conidia ofT. splendens.

An experiment has been designed to determine

whether the fungus is homothal1ic or heterothallicby crossing different isolates derived from singleascospores. The crosses were made by inoculatingsterilized beech cupules placed in moist sterilesand in 6 em Petri dishes incubated at 10-150.

After 4-6 months, apothecia developed in certainpairings. The results of the crosses show that thefungus is heterothallic, since apothecia developed

S. K. Abdullah, E. Descals andJ. Webster 477

Fig. 2. Hymenoscyphus splendens: conidiophores and conidia of TricIadium splendens derived from asingle ascospore culture. Herb. Exr. 3587.

only from crosses between isolates of differentascospores, and did not develop in culturesderived from a single ascospore.

Descals (1978) has shown that several otherisolates of T. splendens produce, in culture, aphialosporic spermatial state, and although wehave no proof, we suspect that they may play arole in sexual reproduction.

Our fungus has been compared with specimensof Hymenoscyphus fagineus (Pers. ex Fr.) Dennisfrom Herb. K, which grows on dry beech cupuleson land (Carre, 1964), but the two fungi are dis-tinct. Our measurements of H. [agineus ascosporesrange from 8'5-12"5 x 3'5-5 pm, and are thereforeappreciably wider than tho se of H. splendens. Theanchoring hyphae described by Dennis (1956) forHelotium fag ineum were not observed, and theectal excipulum was distinct.

Tricladium splendens is known to occupy a widerange of habitats. Its spores are well-knownelements of the spora of rapidly-flowing streamsand foam (Ingold, 1942; Iqbal, 1972), colonizingdecaying leaves and twigs of different plants. It hasbeen regarded as a typical ' aquatic hyphomycete'.

We also find it very commonly on wood and leavesdredged from muddy stagnant ponds and ditches,and it fruits readily on such materials whenincubated in moist chambers. In this respect, itresembles the aero-aquatic fungi which usuallyoccur in these habitats. Bandoni (1972) recordedT . splendens on decaying leaves of Acer macro-phyllum and Quercus robur collected from highwell-drained sites at some distance from streamsor water bodies. Furthermore, Sanders & Webster(1978) found that T. splendens could survive for aperiod of 15 weeks in a terrestrial environment oninfected leaf disks as well as on naturally colonizedleaves from streams. Its apothecial state releasesair-borne ascospores, and it can therefore beregarded as terrestrial. In view of the wide rangeof sub strata on which the anamorph is known tooccur, we would expect the teleomorph to befound on other woody substrata.

Hymenoscyphus tetracladius sp.nov, (Fig. 4)

Apothecia solitaria vel caespitosa, alba, primordiiscylindratis crescentia, ad basim hirsuta, maturitate incupulam infundibuliformem expandentia, minuta,

Teleomorphs of aquatic hyphomycetes

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C

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40/.l ffi

Fig. 3. A-C, Hymenoscyphus splendens, and D, Hymen oscyphus [oliicola: (A) Young apothecia of H.splendens grown in culture on a beech cupule. (B) V.S. apothecium. (C) Asci and paraphyses.(D) Apothecium of Hymenoscyphus foliicola in culture on a beech cupule.

circa 200-300 pm diam et 300 pm alta. Asci clavati,octospori, 50-70 x 9-11 usn, poro cyaneo in KI.Ascosporae ovatae vel fusiformes, hyalinae, 6-10 x3-4'5 pm, aliquando uniseptatae, biseriatae. Para-physes ramosae infra, 2-2 '5 pm latae.

In foliis submersis Fagi, Quercus et Salicis, camerahumida inconditi s. Specimen in Herb. Exr. No.3590 (IM1 255260) ad cupulas Fagi syluaticae cultum,typus est.

Apotheciasingle or in clu sters, white, developingfrom cylindrical primordia, hairy at the base, atmaturity expanding into a funnel-shaped cup,about 2co-300 jim diam and 300 pm high. Asci

clavate, 50-70 x 9-11 /lm in size, pore stainmgdeep blue in Melzer's reagent, S-spored. Asco-spores oval to fusiform, hyaline, 6-10 x 3-4'5 /lm,occasionally r-septate, biseriate. Paraphyses bran-ched below, 2-2'5 /lm wide.

Sp ecimens examined: On submerged leaves of Fagus,Quercus and Salix after incubation in moist chambers.Herb. Exr. No. 3590 is the T ype Specimen (apotheciagrown in culture on cupules of Fagus sylvatica) (1M1255260).

Several collections of a minute white disco-mycete from various substrates have been made.All these collections have been shown to be the

S. K. Abdullah, E. Descals and]. Webster 479

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Fig. 4. Hymenoscyphus tetracladius: (A) Outline of apothecia from culture on beech cupule. (B) Para-physes. (C) Excipulum in optical section and in surface view. (D) Ascospores and asci. (E) Conidiaand conidiophores in culture derived from an ascospore. (B-E) to same scale.

perfect state of a fungus which, in our opinion, isidentifiable as Articulospora tetracladia Ingold. Thedetails of these collections are shown in Table 1.

In all cases, the leaves were collected from smallponds or shallow water habitats. The leaves werewashed with water several times and incubated inmoist chambers for several days at 10-15°. The

apothecia developed after 2-3 weeks. Matureapothecia were allowed to shoot their ascosporeson to 0'1 % malt extract agar with Crystamycin.Single and multi-ascospore cultures were obtainedon fresh 0'1 % malt extract agar plates. The plateswere incubated at 10-15° for 2 weeks. Pieces ofthese cultures were then placed in sterile distilled

Table 1. Collection details of Articulosporatetracladia

2·5·79

Date

23·6·79

Teleomorphs of aquatic hyphomycetes

3-4 JIm, 1-3 septate, 2-3 other arms developsuccessively, 20-40 x 2'5-4 pm, 2-4 septate.

Cultures of the anamorph were sent to Pro-fessor C. T. Ingold for identification. We quotefrom his letter: 'There is no doubt that anArticulospora is concerned, but I do not think itis A. tetracladia. I have looked at a large numberof liberated spores. All were 3-radiate and none4-radiate. Further, the conidia are smaller thanthose of A. tetracladia. The first-formed arm isusually less than 20 pm, and the other two armsare far too short for A. tetracladia. It seems to berather closer to Petersen's A. angulata f. tetra-cladia.'

The anamorph is very common and abundantthroughout the year, and grows on a wide range ofdecaying deciduous tree leaves in streams. Ban-doni (1972) has described the conidia from terres-trial leaf litter. We have also found the conidiadeveloping in moist chambers in almost everysample of leaves and twigs collected from stagnantwater habitats. The fungus seems rather variableand three different forms have been distinguished.We have followed Dyko (1977) in treating thesenames as synonyms.

LocalityWaggoners'Wells, Surrey

Powder MillsFarm, nrPostbridge,Devon

BystockReservoir,nrWoodbury,Devon

Snowdonia FieldCentre, Plas-Tan-y-Bwlch,N. Wales

Snowdonia FieldCentre, Plas-Tan-y-Bwlch,N. Wales

3594 Salix leaves

3593 Quercus leaves

3595 Salix leaves

Herb.Exeter

no.3590 Fagus sylvatica

leaves3592 Salix leaves

water in Petri dishes. All cultures producedtetraradiate conidia identifiable as Articulosporatetracladia within 2 days. A suspension of theseconidia was used to inoculate sterilized cupules ofFagus sylvatica, and these cupules were thenincubated on moistened sterilized sand in a smallPetri dish in a cooled cabinet. Fresh apotheciadeveloped on the inoculated cupules after 2 weeks.Part of the material on beech cupules (HME 3590)was sent to Professor R. P. Korf of CornellUniversity, U.S.A., for identification. We quotefrom his letter: 'All I can say at this point is thatit seems likely that it is a species of Hymenoscyphus.Even that could be easily wrong, however. If it is,whether or not we could match up your materialwith a described species is a good question. Fromthe materials at my disposal, an impossibility,however. The apothecia are tiny for the genus, butnot impossible.' We are unable to match ourspecies with any known Hymenoscyphus species;therefore we are proposing a new name, Hymeno-scyphus tetracladius.

Anamorph: Colonies attain 3 em diam on 0'1 %MEA in 2 weeks at 15°, hyaline to creamy;mycelium mostly immersed, partly superficial,hyaline, septate; colony reverse cream to paleorange. Conidiophores macronematous, mono-nematous, erect; septate, hyaline, branched, up to400 pm long and 2-4 pm wide. Conidia holo-blastic, tetra radiate, hyaline; first arm 15-50 x

Hymenoscyphus foliicola sp.nov. (Figs 3, 5)Apothecia ad 2 mm diam, gregaria vel caespitosa,convexa in statu humectato, concava in statu sicco,stipite longo vel brevi. Hymenium carneum, badiumin statu sicco, circa 100 pm laturn, Excipulum medul-lare textura intricata ex hyphis 3'5 pm latis composi-tum; excipula externa textura globulosa, cellulishyalinis 8-11 pm diam. Asci cylindrati-c1avati, octo-spori, 60-78 x 8-10 ps»: Ascosporae fusoideae, non-septatae,8'5-10'5(12) x 3-4'5 pm, hyalinae, 2-4 guttu-latae, saepe uniseriatae, Paraphyses graciles, septatae,2-2'5 pm diam, ascos attingentes, ad basim ramosae.

In surculis submersis Aceris pseudoplatani, fluvioWest Lyn, Lynton, Devoniae, mensae junio 1979·Herb. EXL No. 3600 (IMI 255261) typus est.

Apothecia up to 2 mm diam, gregarious orcaespitose, slightly convex in moist condition,becoming concave on drying, with a short or longstipe. Hymenium flesh-coloured, turning reddish-brown on drying, about 100 pm thick; medullaryexcipulum of textura globulosa, cells hyaline andabout 8-11 pm diam. Asci cylindric-clavate,60-78 x 8-10 pm, 8-spored; pore stained deepblue in Melzer's reagent, Ascospores fusoid, non-septate, 8'5-10'5(12) x 3-4'5 usn, hyaline, 1-4guttulate, mostly uniseriate; paraphyses slender,septate, 2-2'5 pm diam, equal in length to theasci, branched near the base.

Specimens examined: On decaying submergedtwigofAcer pseudoplatanus, West Lyn River, Lynton, N,Devon, June 1979. Herb. EXL 3600 is the Type

S. K. Abdullah, E. Descals and]. Webster

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Fig. 5. Hymenoscyphus foliicola: (A) Dimorphospora macroconidia and conidiophore. (B) Phialophoresand phialoconidia. (C) Asci. (D) Ascospores. (E) Paraphyses. (A) and (B) drawn from pure culturederived from single ascospore (HME 3600 ).

Specimen (lMl 255261). S. K. Abdullah. Part of thecollection has also been deposited in Herb. R.B.G.,Kew.

A well-decayed twig of A cer pseudoplatanuscollected from the bank of a stream near a water-fall in the River West Lyn, Lynton, N. Devon, on16 June 1979, bore flesh-coloured apothecia.Ascospores were projected on to 0 '1 % maltextract agar with Crystamycin. The ascosporesgerminated overni ght, and single- and multi-ascospore cultures were prepared on the samemedia. The plate s were incubated for 10 days at15Q under NUV (Phillips Black Light). In all cul-tures, the characteristic macro- and phialoconidia

of Dimorphospora foliicola Tubaki were founddeveloping directly on the agar surface (Fig. 5B).

Inoculation of sterilized beech cupules with aconidial suspension of the fungus and subsequentinoculation as described above have also yieldedthe characteristic flesh-coloured apothecia within4 months. These apothecia matched those foundearlier on the decorticated sycamore twig. It wasthus confirmed that the discomycete was theperfect state of D.foliicola. Part of the material wassent to R. B. G., Kew , and originally identified byMr B. M . Spooner as an undescribed species ofPhaeohelotium. However, in a letter dated 31Decemb er 198o, Mr Spooner wrote: 'The

We thank Professor C. T. Ingold, ProfessorR. P. Korf and Mr B. M. Spooner for help inidentification. We also thank Mr H. W. Stubbs forhelp with the Latin diagnoses. One of us (S.K.A.)gratefully acknowledges the grant of study leavefrom the University of Basrah.

The type specimen of the anamorph was isolatedfrom forest leaf litter in Japan (Tubaki, 1958). Ithas also been found on submerged leaves instr eams in England (Ingold, 1958). The fungus isknown from temperate and tropical regions(D udka, 1974). She states that the fungus iscommon in stagnant waters and in terrestrial tosemi-aquatic biotopes. Nilsson (1964) consideredthe fungus as not truly aquatic and ecologicallycloser to the aero-aquatic fungi.

REFERENCES

BANDONJ, R. J. (1972). Terrestrial occurrence of someaquatic hyphomycetes. Canadian Journal of BotanySo, 2283-2288.

CARRE, C. G. (1964). Fungus decomposition of beechcupules. Transactions of the British MycologicalSociety 47, 437-444·

DENNIS, R. W. G. (1956). A revision to the BritishHelotiaceae in the Herbarium of the Royal BotanicGardens, Kew, with notes on related Europeanspecies. Mycological Papers 62. CommonwealthMycological Institute, Kew, Surrey, England.

DESCALS, E. (1978). Taxonomic studies on freshwaterhyphornyceres. Ph.D. Thesis, University of Exeter.

DUDKA, I. A. (1974). Ukrainian aquatic hyphomycetes.A cademy of Sciences of the Ukrainian R .S.R. M .G.Holodny Botanical Institute. Publications ' NaukovaDumka', Kiev.

DYKo, B. J. (1977). A survey of aquatic and water-borne hyphomycetes of the Southern Appalachianmountains, with notes on extra-limital taxa. Ph.D.Thesis, University of Tennessee.

INGOLD, C. T. (1942). Aquatic hyphomycetes of decay-ing alder leaves. Transactions of the British Myco-logical Society 25, 339-417.

INGOLD, C. T . (1958). New aquatic hyphomycetes:Lemonniera brachy cladia, Anguillospora crassa andFluminispora ovalis. Transactions of the BritishMycological Society 41, 365-372.

IQBAL, S. H. (1972). Some observations on aquatichyphomycetes. Ph.D. Thesis, University of Exeter.

NILSSON, S. (1964). Freshwater hyphomycetes, taxo-nomy, morphologyand ecology. Symbolae BotanicaeUpsalienses Uppsala 18, 1-130.

SANDERS, P. F. & WEBSTER, J. (1978). Survival ofaquatic hyphomycetes in terrestrial situations.Transactions of the British Mycological Society 71,231-237.

482 Teleomorphs of aquatic hyphomycetes

discomycete teleomorph of Dimorphospora foli icola in number, ampulliform, 10-15 x 4-6 pm. Phialo-is, on further consideration since my initial conidia spherical, hyaline, 2'0 pm diam, each withexamination, perhaps better placed in Hymeno- a single oil drop, germination not seen.scyphus. It has a rather large-celled excipulumwhich, in a squash mount, appears much like thecellul ar structure characteristic of Phaeohelotium.Ho~ever, I have since examined thin sections,which show the cells to be broadly ellipsoid ratherthan globose, and to be arranged more or less inrows. This is probably better in agreement withthe structure of Hymenoscyphus. That genus is, ofcourse, a huge assemblage of vaguely similar taxa,but for which it is at present impossible to splitinto more meaningful units.

Phaeohelotium was originally proposed forspecie s in which the spores turn brown. That doesnot happen, howe ver, in a number of specie s whichare otherwise structurally similar and, at pre sent,even the tiny species with cellular excipulum, pre-viously placed in Orbili opsis, are merged with it.This arrangement is probably over-simplified and,in view of thi s unsatisfactory definition of thegenus, it would again seem advisable to refer thepresent species to Hymenoscyphus.

I t is difficult to match the species but, as I wrotein my letter of i zth August to Mr Abdullah, itdoes seem very close to Helotium uliginosus Fr. var ,cortisedus Karst. The form and structure appearto be similar, but that species was described ashaving sub-golden guttules in the paraphyses,which are lacking in th is material. I have not seenthe type, and in view of the uncertainty of appl y-ing the name, it is probably best to describe it asnew, but to point out the similarity with H . uligi-nosus v, cortisedus.'

Anamorph:Dimorphospora foliicola Tubaki, J. Hattori Bot .

Lab. 20: 156 (1958).Flumini spora ovalis Ingold, Trans. Br. mycol. So c.

41: 412 (1958). '

Colonies attain 2 ern diam on 0 '1 % MEA in twoweeks at 15°; mycelium mostly immersed, hyalineto cream, septate, branched, 2-4 pm wide; colonyreverse creamy to yellowish brown. Conidiophoresmicronematous to macronernatous, mononerna-tous, branched, septate, erect, hyaline, up to150 lim long and 2-2'5Ilm wide. Conidiogenouscells blastic , 10-15 x 3-5 I'm, terminal, proliferat-ing sympodially. Conidia ovoid to reniform,10-22 x 7'5-10 Ilm in size, hyaline, easily de-tached, unicellular. Microconidial state appearingin culture under the same conditions. Micro-conidiophores macronematous, mononematous upto 60 l im long and 2-3 Ilm wide, septate with 2-3cylindrical br anches, 8-12 x 4-5 pm. Conidio-genous cells phi alidic , apical, penicillate, up to five

S. K. Abdullah, E. Descals and J. Webster

TUBAKI, K. (1958). Studies on Japanese hyphomycetes.V. Leaf and stem group with a discussion of theclassification of hyphomycetes and their perfectstages. Journal of the Hattori Botanical Laboratory20, 142-244.

WEBSTER, J. & DESCALS, E. (1979). The teleomorphs ofwater-borne hyphomycetes from fresh water. InThe Whole Fungus, Vol. II (ed. W. B. Kendrick),

pp. 419-451. Ottawa, Canada: National Museum ofNatural Sciences.

WEBSTER, J. & DESCALS, E. (1981). Morphology, dis-tribution and ecology of conidial fungi in fresh waterhabitats. In The Biology of Conidial Fungi (ed. G. T.Cole & W. B. Kendrick), pp. 295-355. New Yorkand London: Academic Press.

(Received for publication 12 February 1981)