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AQUATIC HYPHOMYCETES FROM SWITZERLAND

By C. T. INGOLDDepartment of Botany, Birkbeck College, London

(With 3 Text-figures)

Working in Britain I found a special flora of aquatic Hyphomycetesgrowing on submerged decaying leaves of broad-leaved trees and shrubsin streams and other well-aerated water. Some twenty-five species of thesefungi were recognized. Six had previously been described, though ratherimperfectly, but their special relationship to submerged leaves had notbeen appreciated.

My early work (Ingold, 1942) was limited to a small stream in Leicester­shire, but later, scattered observations (Ingold, 1943) covering England,Wales and Ireland, showed that this flora was widespread, and suitabledecaying leaves from any stream never failed to give crops of these fungi.

The examination ofleaves from other localities in the British Isles addedonly a few to the list of species reported from the stream in Leicestershire,and, although intensive search would almost certainly add a few to the listof species already known, it is doubtful if many more await discovery.

It was clearly of interest to know if the same flora was to be foundelsewhere in Europe and, on a short visit to Switzerland in the late summerof 1947, I took the opportunity to study the fungi of submerged decayingleaves of willow and alder in alpine waters. My observations were madepossible by the kindness of Prof. E. Gaumann of Zurich who not only lentme a microscope and other necessary apparatus, but also suggested anexcellent locality (Surlej-Silvaplana) for my operations.

Surlej (1800 m.) lies in that valley of the Upper Engadine which includesa series of lakes (St Moritzersee, See von Campfer, Silvaplanersee andSilbersee) linked by short stretches of river. Bordering these stretches, oneither side of the main channel, are patches of willow scrub, floodeddoubtless when the river is in spate, but through which in summer theretrickle occasional small streams. Willow leaves from these small streams wereexamined in the region between St Moritzbad and the See von Compfer.In addition to the main river, there are numerous little torrents cascadingdown the mountain sides to join the water system of the valley. The steepsides of the valley up to about 2 IOO m. bear a fine coniferous forest, butbordering the torrents are alders and willows. Decaying leaves of these,caught between the small boulders of the streams, were also examined.

It was at once apparent that the decaying leaves, both from the mainstream and from the tributary torrents, bore rich crops of aquaticHyphomycetes.

Altogether six collections, each of 10-20 leaves, were carefully examined.These yielded nine known species (Table I and fig. I) and, in addition,

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342 Transactions British Mycological Societyan interesting new fungus apparently referable to the genus Anguillospora,All these species figured in more than one collection.

Table I

SpeciesAlatospora acuminata IngoldLemonniera aquatica de Wild.Flagellospora curvula IngoldTetracladium marchalianum de Wild.Articulospora tetracladia IngoldTricladium splendens IngoldHeliscus aquaticus IngoldTetracladium setigerum (Grove) IngoldTricladium angulatum Ingold

ryt2a 2c

8a

NotesVery abundantVery abundantVery abundantVery abundantAbundantSeen three timesSeen twiceSeen twiceSeen twice

1a

Fig. I. Aquatic Hyphomycetes drawn with the aid of a camera Lucidafrom specimens collectedin Upper Engadine. I, Lemonniera aquatica, a, conidiophore with two developing spores;b, spore. 2, Articulospora tetracladia, a, conidiophore with one ripe spore; b, conidiophore withtwo developing spores; c, spore. 3, Flagellospora curoula, conidiophore bearing two spores.4, Heliscus aquaticus, spore. 5, Tricladium angulatum, conidiophore with one ripe spore and anunbranched spore-primordium. 6, Tricladium splendens, conidiophore with ripe spore.7, Alatospora acuminata, a, conidiophore with ripe spore; b, liberated spore. 8, Tetracladiummarchalianum, a, conidiophore bearing one nearly mature spore and an unbranched spore­primordium; b, spore. 9, Tetracladium setigerum, conidiophore bearing one mature spore anda spore-primordium developing its first lateral branch.

These organisms clearly formed the characteristic fungus flora of thedecaying leaves and, although a few pythiaceous fungi were seen, theywere few and far between. Submerged decaying leaves of herbaceousplants and of conifers were examined, but no trace of aquatic Hypho­mycetes was found on them.

Aquatic Hyphomycetes. C. T. Ingold 343With the exception of Tetracladium marchalianum these fungi are recorded

for the first time from Switzerland. De Wildeman (1894) reportedT. marchalianum from a pond in Geneva. However, even the restrictedconception of that species which he proposed in 1894 included at leasttwo species (see Ingold, 194'2) and, as he gave no figures of the Genevamaterial, it is not possible to say what species he actually observed.

A noteworthy feature of the list (Table I) is the absence of Clavariopsisaquatica and Anguillospora longissima which are almost invariably present onsubmerged decaying leaves from streams in Britain.

Anguillospora fiagellifera n.sp.

This fungus (Figs. '2 and 3) was found in the first instance on a submergedleaf decayed too far for certain identification, but it was later collected ona decaying willow leaf from another stream.

The mycelium is branched, septate, hyaline and ramifies in the tissueof the leaf, from which the conidiophores grow out at right angles. Theconidiophore is simple, narrow ('2 f.L diam.) towards its base, but inflatedncar its apex (6- 9 f.L diam .). The single elongated, hyaline conidium(aleur iospore) is terminal. It is 14O-200f.L long, truncate at its base wherethe diameter is 6-8f.L, but it widens upwards becoming 10-14f.L broad ata distance of 40-50 f.L from the base, but above that it narrows, to forma whip-like terminal part only 2-3 f.L in diameter. This whip-like end iscurved in such a way that th e spore does not lie in a single plane. Theconidium has 4-6 septa and is very pearly in appearance no doubt due toto a reserve of glycogen. When mature the spore separates from its coni.diophore apparently by the breakdown of the middle lamella at thejunction between the two. Germination is by a single, very straight germtube developed laterally from near the base of the lowermost cell of thespore, quite often before it is shed. The liberation of the spore does notnecessarily bring the activity of the conidiophore to an end , for it may growout laterally, below the scar left by the separation of the first spore, andgive rise to a second.

The reference ofthis well-marked species to the genus Anguillospora seemsjustified because it is an aquatic Hyphomycete with a worm-like spore ofthe aleuriospore type borne singly on a conidiophore which is usuallysimple. It differs from the only other species, A. longissima, in a number ofways. First, the spore is wider and its two ends are strikingly different,whilst in A. longissima it is almost impossible to distinguish base from apexin the liberated conidium. Secondly, the conidium germinates by a singlelateral germ-tube arising from the basal cell, but that of A. longissimagerminates by basal and apical tubes in line with the longitudinal axis ofthe spore. Thirdly, the conidiophore with its inflat ed apex contrasts withthat of A. longissima, for in that species it is difficult to be sure, until thespore is about to be shed, where the conidiophore ends and the conidiumbegins. Fourthly, no separating cell, such as occurs in A. longissima, isdeveloped.

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344 Transactions British Mycological Society

Fig. 2. Angudlospora flagellifera. Conidiophores with conidia. Contents shown only in a and b.In e and f the conidium has germinated while still attached. In e,f, g and h scars left bydetached conidia are shown. In h a very young spore-primordium is shown to the right ofa mature spore.

Fig. 3. Anguillosporaflagellifera. Conidia, most of which have started to germinate.

Aquatic Hyphomycetes. C. T. Ingold 345

Anguillospora fiagellifera sp.nov.

Fungus submersus aquaticus, mycelio repente, hyalino, septato,ramoso. Conidiophora simplex, basim versus 2 fL lata, summa parteinflata 6-9fL lata. Conidium (aleuriospora) acrogenum, hyalinum,4-6 septatum, vermiforme vel falcatum, 14o-2oofL longum, ad basimtruncatum 6-8fL latum, in medio 10-14fL latum, ad apicem filiformecurvatum et ad 2-3fL diam. attenuatum. In germinatione oritur unalateralis hypha solum e conidii infima cellula.

Hab. In foliis putrescentibus in flumine submersis, in Valle EngadinHelvetiae.

SUMMARY

Aquatic Hyphomycetes form the characteristic fungus flora of submergeddecaying leaves of alder and willow in Switzerland as in Britain. Leavescollected from streams in the Upper Engadine in August 1947 yielded ninespecies already reported from Britain and, in addition, a species, Anguillo­spora fiagellifera, apparently new to science.

REFERENCES

DE WILDEMAN, E. (1894). Notes mycologiques. Fascicle 3. Ann. Soc. Beige. Microsc.XVIII, 135-61.

INGOLD, C. T. (1942). Aquatic Hyphomycetes of decaying alder leaves. Trans. Brit.mycol. Soc. XXV, 339-416.

INGOLD, C. T. (1943). On the distribution of aquatic Hyphomycetes saprophytic onsubmerged decaying leaves. New Phytol. XLII, 139-43.

(Accepted for publication 27 July 1948)

NOTE. Since this paper was accepted, I have found Anguillosporaflagelliferaon a decaying leaf from a small lake at Clandeboye, Co. Down, Ireland,during the Autumn Foray, 1948.