Dermoloma cuneifolium (Fr.: Fr.) Bon |
(= D. atrocinereum (Pers.: Pers.) Orton)
(= D. fuscobrunneum Orton)
British distribution: Throughout Britain
World distribution: ?
Dermoloma is a small genus of white-spored toadstools, with D. cuneifolium generally the commonest species in Britain. Dermoloma species occur in and are used to characterise waxcap grasslands.
|Dermoloma cuneifolium in upland pasture over basalt, Muirshiel, Renfrewshire, October 2000.|
|Dermoloma cuneifolium, young, damp material (hence dark cap colour), in upland pasture over basalt, Muirshiel, Renfrewshire, October 2004.|
Dermoloma cuneifolium occurs with waxcaps (Hygrocybe spp.) in 'unimproved' pastures that have not been reseeded or subjected to chemical fertilisers, i.e. those pastures that constitute 'waxcap grasslands'. In south-west Scotland, current experience is that it is typical of richer sites developed over ultrabasic rocks (basalt and serpentinite), but nationally it evidently occurs over a range of rock types. It can also occur at woodland margins. It has rather thick gills and a chunky habit that is similar to Hygrocybe species and this may be convergent evolution, perhaps related to desiccation resistance?
Identification and variation
Dermoloma species have a "cellular" cap cuticle, i.e. terminal elements inflated and appearing as rounded "cells" in surface view. Doubtless because of this, the cap often cracks as a desiccation effect and D. cuneifolium has been given the newly-fabricated common name of 'Crazed Cap', presumably not a comment on its mental state. Colours are dull greys and browns. Spore-prints are white.
Dermoloma cuneifolium has non-amyloid spores, i.e. a spore-print does not turn a blue-black colour when a drop of Melzer's Iodine reagent is added — though a reddish (dextrinoid) reaction may be seen. The species as currently understood includes D. fuscobrunneum, with a darker brown cap, and D. atrocinereum, variously described and with a smoother, pruinose, white stem. Full descriptions of these were given by Watling & Turnbull (1998), but Arnolds (1995) regards D. cuneifolium as one, moderately variable species, in which characters of colour, habit and spore-size intergrade and do not show correlation. At times my field impression has been of more than one entity, but with colours changing slightly after collection and lacking any clear separation on subsequent examination. It may yet be that DNA analysis of a sufficient range of material, with explicit comparison with micro-morphological characters (as distinct from supposed indentifications on unstated criteria) will give a greater insight and perhaps reveal semi-cryptic species.
Other British Dermoloma species are rare or overlooked, are of very similar appearance and have amyloid spores when tested with Melzer's Iodine. Watling & Turnbull (op.cit.) and Arnolds (op.cit.) give good descriptions (D. pseudocuneifolium, D. josserandi, D. phaeopodium), but do not include the recently recognised D. magicum (see Legon et al., 2005), which discolours orange-red and then black, especially at the stipe base.
|• ||Arnolds, E.J.M., (1995). Dermoloma, in Bas, C., Kuyper, T.W., Noordeloos, M.E., & Vellinga, E.C. (eds.), Flora agaricina Neerlandica, 3, A.A.Balkema, Rotterdam, pp.30–34.|
|• ||Legon, N.W., Henrici, A., Roberts, P.J., Spooner, B.M., & Watling, R., (2005). Checklist of the British & Irish Basidiomycota, Royal Botanic Gardens, Kew.|
|• ||Watling, R., & Turnbull, E. (1998). British Fungus Flora, Agarics and Boleti. 8. Cantharellaceae, Gomphaceae and amyloid-spored and xeruloid members of Tricholomataceae (excl. Mycena). Royal Botanic Garden, Edinburgh.|