By D.W. Minter

CABI Bioscience, Bakeham Lane, Egham, Surrey, TW20 9TY, UK



Ascodichaena,    Coccomyces,    Colpoma,    Cryptomyces,    Cryptomycina,    Cyclaneusma,    Elytroderma,    Hypoderma,    Hypodermella,    Hypohelion,    Lirula,    Lophodermella,    Lophodermium,    Melittosporium,    Meloderma,    Naemacyclus,    Potebniamyces,    Propolomyces,    Rhytisma,    Sporomega,    Terriera,    Therrya,    Tryblidiopsis


After a brief discussion of the order, all genera and species of the Rhytismatales known from Ukraine are listed with notes, full dichotomous keys and some illustrations. The following fungi are reported as new for Ukraine: Colpoma ledi, Lophodermium aucupariae, Lophodermium maculare, Melittosporium versicolor, Tremella juniperina; the following are removed from the Ukraine list as having been based on incorrect identifications: Cryptomycina filicina, Lophodermium melaleucum.


The Rhytismatales, or tarspot fungi, are a middle-sized order of ascomycetes, containing 3 accepted families, 71 genera which are accepted or of unknown application, plus 36 known generic synonyms, and 411 accepted species (Hawksworth et al., 1995). Although these numbers are all probably rather conservative, the European component of the order is now sufficiently well-known to make useful identification guides possible. In the summers of 1993-1996, there was intense collecting of this group in Crimea and the Carpathian Mountains as part of preparatory work for the recently published checklist of Ukrainian fungi (Minter & Dudka, 1996); then, in the summer of 1998, there was further collecting of these fungi in Volyns'ka Oblast as part of the Royal Geographical Society's first Ralph Brown Expedition. A guide to the Ukrainian members of this order is therefore particularly timely.

It is the aim of the present work to review the status of this order in Ukraine more critically than was possible in the generalized checklist, to provide identification keys to all genera and species of this order known from Ukraine, and to illustrate selected species. Where they are already available in the recently published checklist, synonymy lists and bibliographic information about where each name was published are omitted from the present work. Each species entry is accompanied by notes on status in Ukraine, months in which it has been observed in Ukraine, regions of Ukraine where it has been seen, the habitat it occupies in Ukraine, brief notes about the fungus (particularly on how to find it and distinguish it from similar species), brief observations about its worldwide status, and bibliographic references providing information about the fungus in Ukraine, or access where possible to a full formal description or an illustration of the fungus if none is provided in the present work. The keys in the present work aim to permit identification in field conditions wherever possible. Host identity is therefore more frequently used as a diagnostic character than in more formal keys.

The work is based on information in the Cybertruffle suite of relational computerized databases, which include a copy of the data used to produce the recent checklist and many other records of tarspot fungi from other parts of Europe and the rest of the world (Minter, 1996). The present work also includes information from collections made during field work too recent to incorporate in that checklist. Potential records of tarspot fungi known only as anamorphs, particularly members of the genera Leptostroma Fr. and Melasmia Lév. are excluded from the present treatment.

Fruitbodies of tarspot fungi are found on dead plant material, usually leaves, twigs, bark, wood or female conifer cones, occasionally also berries. Although many different plant species can be colonized, they are particularly abundant on conifers, grasses and the Ericaceae. It follows that they tend to be found more in forests and nature reserves (particularly those with rather acid soils) than in agricultural or urban environments. Usually the plant part colonized is totally dead, and has already fallen into the litter, but in some cases the leaf, twig or other part remains attached to the plant, and may even still be alive, with only a small part dead and bearing the fruitbodies. Some species are known to inhabit apparently healthy plant tissues as symptomless endobionts, fruiting only after normal senescence, and these are now attracting much interest.

A characteristic feature of many leaves and twigs colonized by tarspot fungi is that the tissues tend to be paler than parts colonized by other fungi. Species occurring on twigs also tend to make those twigs rather brittle, and there is some evidence that some tarspot fungi have a rôle in helping trees maintain a good crown through self-pruning. Zone lines produced by the fungus are also quite common. Many tarspot fungi produce a conidial state before the ascomata are formed, and both states are almost invariably deeply embedded in the plant tissues. The conidial state usually takes the form of blackish pycnidia which contain minute single-celled conidia which probably function as spermatia.

The ascomata, which follow the pycnidia, are larger but also usually black, opening with one to several splits in the covering layer to reveal the hymenium. Paraphyses are usually present. Asci are mostly thin-walled, with only one functional wall layer and an apex which almost never blues in iodine. The ascospores are almost invariably colourless, usually aseptate, and often long and thin. Gelatinous material is almost always present somewhere inside the ascoma, most frequently as a coat on the ascospores and paraphyses (where it may be pigmented towards the top of the hymenium). Spore release is mostly violent in humid conditions.

The zone lines, pycnidia and ascocarps produced by tarspot fungi are all long-lasting, so that they are usually all seen at the same time in the field, and observational work can be carried out at any time of year. With practice, many species can be identified reliably in the field with a hand-lens, so it is often not necessary to collect samples: field observations are sufficient to generate records on their status and distribution. Most tarspot fungi are found only on particular plants, and on those plants the habitat they occupy is usually well-defined.

To record these fungi it is therefore merely necessary to find the correct associated plant and then the correct part of that plant in the correct conditions for the tarspot fungus required. If the fungus is then not encountered by an experience field worker, it is entirely possible that it is simply not present: such unsuccessful searches can help to define distributions much more closely than is possible for fungi with ephemeral fruitbodies. Where the fungus does not have a known preferred plant, or where the exact niche is not properly understood, collecting can be largely a matter of chance. Less than 10% of the species of Rhytismatales known to occur in Ukraine still have to be recorded in this manner. In Britain, where about 25 more species of this order are known to occur than in Ukraine, this percentage is rather higher, suggesting that further collecting in Ukraine will reveal more species with improperly understood niches. For these, serendipity remains the most important factor in generating new records.

Weather conditions can greatly affect field work with these fungi. In general bright sunny days are not good for observation: ascomata are closed, and the strong contrast of light and shadow makes it difficult to see the small black spots which are the fruitbodies. Field work in snowy conditions can cause similar difficulties. Too low light levels are also unfavourable. The best conditions are therefore usually overcast but rather bright, and during or immediately after rain, or when snow is rapidly melting. If collections are desired, it is important to remember the species may be rare. Tarspot fungi are easily collected, and the only items necessary in the field are a hand-lens, knife, secateurs, waterproof pen, and paper envelopes in a range of sizes to hold the collections.

Key to Genera known from Ukraine

1 conspicuous stromata produced on living dicot leaves (in Ukraine only known from Acer, Andromeda and Salix spp.); each stroma then bearing many conidiomata and, after leaf death, many ascomata Rhytisma
not with this combination of characters


2 (1) on living or dead bark of the Fagaceae, often causing extensive black crusts, often looking like a lichen; ascomata rarely observed; asci saccate, opening with a large apical tear; ascospores ellipsoid, without a mucous sheath Ascodichaena
not with this combination of characters


3 (2) on dead brittle attached or self-pruned conifer twigs and branches (in Ukraine known only from Picea spp.); conidiomata and ascomata so strongly erumpent as to appear superficial; conidia almost filiform; ascospores 1-septate, with a conspicuous mucous sheath Tryblidiopsis
not with this combination of characters


4 (3) on dying or recently dead wood or bark attached to living trees (in Ukraine known only from Salix spp.), often causing an extensive black crust, typically with a paler orange coloured perimeter; ascomata containing cylindrical asci with ascospores each with inconspicous apical and basal appendages Cryptomyces
not with this combination of characters


5 (4) on fronds of ferns Cryptomycina
not with this combination of characters


6 (5) on wholly or occasionally partly dead needles of Pinus spp.; ascomata opening by a pair of flaps, but with no blackened upper wall; ascospores 2-septate, boomerang-shaped, each with an apical and basal mucous cap Cyclaneusma
not with this combination of characters


7 (6) on pale dead parts of otherwise living attached needles of Pinus spp., usually infecting only a small number of trees in a stand; ascomata inconspicuous, externally pale brown or grey, elongated; ascospores clavate, aseptate, with a conspicuous mucous sheath Lophodermella
not with this combination of characters


8 (7) on wholly dead conifer needles still attached to living twigs (in Ukraine known only from Abies, Picea and Larix spp.), often with 1 conspicuous black zone line at the needle base 9
not with this combination of characters


9 (8) ascomata usually long and thin; ascospores threadlike; paraphyses long (in Ukraine known only from Abies and Picea spp.) Lirula
ascomata elliptical; ascospores clavate; paraphyses short (in Ukraine known only from Larix spp.)


10 (8) on dead parts of otherwise living needles of Pinus spp.; ascomata conspicuous; asci saccate, very large; ascospores 1-septate, with a thick mucous sheath (in Ukraine known only from one locality in Crimea) Elytroderma
not with this combination of characters


11 (10) on pale, brittle, often self-pruned conifer twigs (in Ukraine known only on Pinus spp.); ascomata circular; ascospores septate with mucous sheaths which are very thin or absent Therrya
not with this combination of characters


12(11) ascomata deeply embedded in dead attached needles or scales of fallen cones of Pinus spp. [probably common], with no obvious blackened upper wall, opening by short radial splits; the opening eventually appearing like a circular pore; ascospores septate Naemacyclus
not with this combination of characters


13 (12) ascospores with a length/width ratio greater than 8:1 14
ascospores with a length/width ratio less than 8:1


14 (13) ascomata opening with radial splits (if this option is unsuccessful for bark or wood-inhabiting species, try Colpoma under the alternative option) 15
ascomata opening by a single split


15 (14) ascomata in a thickened fleshy stroma with a gelatinous interior, and a blackened outer crust Sporomega
ascomata lacking a thickened fleshy stroma


16 (14) on twigs or bark (nb if on twigs of the Ericaceae, try Lophodermium under the alternative option); ascomata often > 1.5 mm in their largest dimension, often with a strongly-developed basal layer and a poorly-defined perimeter Colpoma
on angiosperm leaves, conifer needles, conifer cones or twigs of the Ericaceae; ascomata usually < 1.5 mm in their largest dimension, often with a poorly-developed basal layer and a well-defined perimeter


17 (16) on twigs; ascomata with paraphyses forming an epithecium Terriera
on various substrata including twigs of the Ericaceae; ascomata with paraphyses not forming an epithecium


18 (13) on dead conifer needles, usually on dead twigs still attached to living branches; ascomata containing ascospores with a very conspicuous mucous sheath Meloderma
not with this combination of characters


19 (18) upper wall of ascoma with much strongly blackened fungal tissue, opening by one or more splits, but remaining attached to close and re-open with changing humidity 20
upper wall of ascoma with little or no blackened fungal tissue and usually shed, when spore release begins, to expose the often deeply embedded hymenium


20 (19) ascomata opening with more than one radial split, on bark of trees of the Rosaceae Potebniamyces
ascomata opening with a single longitudinal split, on various dead leaves, twigs and stems


21 (20) ascomata without a blackened lower wall; upper wall of ascoma undifferentiated and without a pre-formed split line; paraphyses apically swollen Hypohelion
ascomata with a blackened lower wall; upper wall of ascoma with different zone and a pre-formed split line; paraphyses not apically swollen


22 (19) ascospores aseptate Propolomyces
ascospores septate



The UK Government's Department of the Environment Darwin Initiative and the Trustees of the Ralph Brown Fund (Royal Geographical Society) are warmly thanked for the financial assistance which made this work possible. The Directors of the International Mycological Institute and the M.G. Kholodny Institute of Botany are thanked for their support. Mr Eugene Yurchenko of the Institute of Experimental Botany, Minsk, Belarus, is thanked for supplying some of the collections on which this work was based. Prof D.L. Hawksworth and Mrs H.M. Minter are thanked for their comments on the manuscript.