Airborne conidia of Belemnospora

Notes and brief articles formation , function and dynamics. Plane and Soil 71, 9-2 1. NEWELL, K . ( 19 84) . Interaction between two decomposer basidiomycetes and a collembolan under Sitka spruce : pattern, abundance and selective grazing. So il B iology and Biochemistry 16, 227-233. PETERSEN, P . M. (19 77) . Investigations on the ecology and phenology of the macrornycetes in the Arctic. Meddelelser Om Grenland 199, 1-72 . RICHARDSON, M . J. ( 19 70). Studies on Russula emetica and other agarics in a Scots pine plantation. Transactions of the British M y cological Society 55, 217-229. SINGER, R. (1945). The Boletineae of Florida with notes on extralimital species. II. The Boletaceae (G yro poroideae). Farlo wia 2, 223-303 . SNELL, W . H. & DICK, E. A. ( 1970 ). The Boleti of Northeastern North America. Lehre, G .F.R. : J. Cramer.

FOGEL, R. ( 19 82). Quantificationofbasidiocarps produced by hypogeous fungi. In The Fungal Community (ed, D . T. Wicklow & G . C. Carroll), PP .553-568. New York, U .S .A . : Marcel Dekker. GREIG-SMITH, P. ( 19 83 ). Quantitatiue Plant Ecology, jrd edn, In Studies in Ecology 9 (ed . D . J. Anderson, P . Greig-Smith & F. A. Pitelka). Berkeley, U.S .A. : University of California Press. HERING, T . F. (19 66 ). The terricolous higher fungi of four Lake District woodlands. Transa ctions of the British Mycological Society 49, 36~383. LAIHO, O. (1970) . Paxillus inoolutus as a mycorrhizal symbiont of forest trees. Acra Forestalia Fenni ca 106, 1-7 2 •

LANGE, M. ( 19 48) . The agarics of Maglemose. Dansk Botanisk Arkiv 13, 1-141. LAST, F . T ., MASON, P . A., WILSON, J. & DEACON, J. W. ( 19 83) . Fine roots and sheathing mycorrhizas : their

AIRBORNE CONIDIA OF BELEMNOSPORA URSULA ALLITT

20 Acrefield Drive, Cambridge CB4 IJP

Conidia trapped from the air in Cambridge are compared and identified with the conidia of Belemnospora uerruculosa. Subsequently the genus Belemnospora, and two species in this genus were described (K irk 1981 ). It seemed possible that the airborne conid ia could be those of a member of this genus, although they did not precisely match the descriptions of the conidia of either of the two species of Belemnospora. A third species, B . verrucu/osa P. M. Kirk was later described (K irk & Spooner, 1984), and almost all

During a survey of the fungal spores present in the air of Cambridge from 1968 to 1971, unknown spores (F igs 1-9) were found on the traces obtained from a Burkard Automatic Volumetric Spore Trap (BA VST), in low numbers on many days. Similar conidia were trapped in later years (F igs 10-12). These spores were clearly conidia, but could not be identified as the conidia of any known fungus.

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Figs 1-10. Airborne conidia identified as of Belemnospora uerruculosa . Figs 11, 12. Airborne conidia resembling conidia of B . epiphylla. Figs 13-19. Conidia of B . uerru culosa. Figs 20, 21. Unidentified airborne conidia superficially resembling conidia of B. uerruculosa ,

Trans. Br, mycol. Soc. 85 (3) , (19 85)

Printed in Grear Britain

Notes and brief articles ofthe airborne conidia resembled the conidia of this species (Figs 13-19). In airborne conidia there are many slight variations in shape, which is usually narrowly ellipsoidal, but with a wide truncate base, (1'5-) 2' 5-3'0 (-4'0) pm wide. The base may also have material around its circumference giving the appearance of a narrow flange (Figs 1, 6). Occasionally conidia are released before any septa have formed (Fig. 1) but most conidia have one septum near the centre ofthe spore (Figs 2-7). Conidia with two or three septa are only rarely seen (Figs 8, 9). There may be a slight constriction at the septa (Figs 4, 8). The conidia are shades of pale golden brown, Methuen colour 4, A 3-4 (Kornerup & Wanscher, 1978). Some conidia appear to be smooth (Figs 2--6, 8,9) and although a few ofthese prove to be very slightly verruculose with the use of a x 100 objective, this would not be visible with the x 50 objective normally used for routine scanning in aerobiological studies. Other conidia range from slightly to clearly verruculose (Fig. 1), sometimes with a few coarse spines, seen in surface view in Fig. 7. The size range is (7'0-) 8'0-11'0 (-14'0) x 3'0-5'5 fLm, Observations ofthese conidia were supplemented by a detailed analysis of all the conidia of this type found on the traces for 19-27 Sept. 1982 obtained from a BAVST at the Cambridge University Botanic Garden. In all 35 conidia were found. Of 33 conidia, two were aseptate, 24 had one septum, five had two septa, and two had three septa. Only eight were obviously ornamented, the remainder were apparently smooth. The size range was 6'5-12'5 x 3'0-5'5 fLm wide at the broadest point, and the base measured 2'0-3'5 (-4'0) pm. There was a tendency for the conidia to occur in small clumps; three pairs of conidia were seen, a tendency also noticed in the conidia trapped earlier. The mean daily concentration for the period of 8 days was 22 conidia m- 3 of air. In one case both the conidium and the conidiophore on which it was borne became airborne together (Fig. 10). The two remaining conidia (Figs 11, 12) resembled the narrower, r-septate conidia of B. epiphylla P. M. Kirk rather than those of B. verruculosa. The conidia of B. verruculosa IMI 250716a (Figs 13-20) were well illustrated and briefly described by Kirk & Spooner (1984), the description being based on the holorype, IMI 252672a. Photomicrographs of conidia from IMI 250716a show a range of conidia: aseptate (Figs 13, 14), with one septum (Figs 15-18), apparently smooth (Fig. 15), verruculose (Fig. 16), and with a few coarse spines (Figs 17, 18). A very young conidium, still attached to the conidiophore, is shown in Trans. Br. mycol, Soc. 85 (3), (1985)

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Fig. 19. The size range of the conidia was 7'0-10'5 x 3'0-4'5 pm, while the bases measured 2'0-3'0 pm. A narrow flange was visible at the base of some conidia. The colour was pale golden brown, Methuen colour 5, A4-B3. Most of the airborne conidia matched those of B. verruculosa very well. The airborne conidia showed a somewhat greater overall size range and size range of base diameter, but since the airborne conidia must originate from many sources this greater variability is not unexpected. The airborne conidia were a little paler, and with a higher proportion of apparently smooth conidia, which suggests that they often become airborne before pigmentation and the formation of the ornament is completed. The slight discrepancy in shape between the mostly narrowly ellipsoidal airborne conidia and the mostly more or less cylindrical reference conidia is probably also attributable to the younger age of the airborne conidia: the younger reference conidia (Figs 13, 14, 19) are narrowly ellipsoidal. Kirk (1981) made the point that B. epiphylla and B. pinicola P. M. Kirk are widespread but uncommon in the British Isles, and are possibly often overlooked. B. verruculosa, which is common enough for its conidia to be detected in the air regularly throughout the growing season, would also seem to have been overlooked because it is inconspicuous. It also seems possible that it would occur on other dead stems, as well as those of Rhododendron ponticum and Phragmites australis (Kirk & Spooner, 1984). There is another type of airborne spore, as yet unidentified (Figs 20, 21) which superficially resembles the conidia of Belemnospora in size and overall shape, and in having more or less truncate ends. These spores are however broader, 4'5 pm wide, darker, Methuen colour 4, A&--7 or B4-5, have thicker walls, about o-5 pm thick, and may occur in short chains. When previously attached to another spore the end of a conidium has a small pore, and the wall is slightly thickened around the pore. I would like to thank Dr P. M. Kirk for reference material of B. verruculosa and Professor R. G . West for photographic facilities. REFERENCES

KIRK, P. M. (1981). New or interesting microfungi. II. Dematiaceous hyphomycetes from Esher Common, Surrey. Transactions of the British Mycological Society 77,279-297·

KIRK, P. M. & SPOONER, B, M. (1984). An account of the fungi of Arran, Gigha and Kintyre. Kew Bulletin 38, 503-597.

KORNERUP, A. & WANSCHER, J. H. (1978). Methuen Handbook of Colour, 3rd ed. London: Eyre Methuen.

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