CA Mushrooms
CA Mushrooms

Book Review

Hebeloma (Fr.) P. Kumm.
Fungi Europaei Volume 14

By Henry J. Beker, Ursula Eberhardt, & Jan Vesterholt
2016, Edizioni Tecnografica
ISBN 978-88-96059-42-5
Hardbound, xiv + 1218 p.
Fungi Europaei

Those familiar with the series, Fungi Europaei, know that the volumes are large (heavy!), comprehensive, well illustrated treatments of genera, groups of genera, or families of agarics, boletes, polypores, and corticioid fungi that occur in Europe. Well, this most recent addition to the series has set a new record for size, with over 1200 pages (in rather small fonts), nearly 3000 photographs, and weighing in at about 9 lb. All of that dedicated to a group that one well known author characterized as “another faceless and featureless collection of brownish mushrooms.” Truth be told, they’re not entirely featureless, especially if you have a microscope, although they’ll probably never receive the attention that the brightly colored hygrocybes and amanitas draw. But fortunately for folks who want to identify all the fungi they encounter, the European trio of Beker, Eberhardt, and the late Jan Vesterholt has produced this hefty tome to provide a starting point for understanding hebelomas. Be forewarned, however, that the authors caution that “Hebeloma will never be an easy genus in terms of species identifications.”

The primary language in which the books in this series are written varies, as does the particular material (typically keys and/or summary descriptions) that is repeated in additional languages. In this case, the primary is English, with the keys also appearing in German, French, and Italian. Original diagnoses appear in the language in which they were published and in English translation.

The organization of the book is typical for the series. Introductory material consists of a Brief Introduction and Background (of the genus), Hebeloma Ontogeny and Morphology (macroscopic and microscopic), Our Approach (to collecting, color description, microscopy, database, molecular analyses, species recognition, and taxonomic and nomenclatural issues [they encountered many of both!]), Infrageneric Classification and Molecular Results, and Keys. This is followed by the main portion of the book — seven “chapters” that present the species accounts organized by taxonomic section. Things wrap up with Ecology and Habitat Keys, an Annotated List of Published Names from Europe and Africa, Bibliography, Iconography (over 500 pages of images!), and the Index.

Dichotomous keys are provided both to the sections and to the species within each section. The leads are mostly simple, usually involving only one or two features. Features of the spores and cheilocystidia are used frequently, so access to a microscope is necessary.

The section treatments each include the authority, MycoBank registration number, Basionym, information about Types, Synonyms, Etymology, Original Diagnosis (and English Translation of those in other languages), a general macroscopic and microscopic Description, summary of Molecular Results (including one or more phylogenetic trees), and Commentary and Discussion, such as how to distinguish the often similar looking species in the section and consideration of subsections. For each section that includes more than one species, a table comparing key features of all the species is provided. For mushroomers with an aversion to dichotomous keys, these tables could be used as synoptic keys once the appropriate observations had been made and the proper section identified.

The species accounts each include pretty much the same information as is provided for the sections, plus Habitat and Distribution, Collections Cited, and Selected References. The text is augmented with line drawings of basidia, spores, and cheilocystidia, tables of spore and cheilocystidia measurements, and, in cases where sufficient collections exist to allow it, a distribution map and bar chart showing fruiting by month. A reference to the images in the Iconography section is also provided.

The Iconography section is impressive. It begins with 10 pages of non-species- specific images. These include examples of the dextrinoid reaction (a reddening of the spore or other microscopic structure when mounted in Melzer’s reagent) in spores, overview phylogenetic trees, a couple of principal components analysis charts showing how species can be differentiated by average (cheilocystidium) apex width, average spore area, and average number of complete gills, and some photos of ectomycorrhizal root tips. The speciesspecific images comprise the balance of the 500+ pages in the section. For nearly all the species, multiple field photos are provided, followed by micro photos of spores and cheilocystidia. The spores usually are shown mounted both in Melzer’s reagent and KOH, and first focused to show shape and color, and then on the top of the spore to show the ornamentation. Images of the cap cuticle structure are shown for many species. Assorted other images are included for some species, such as lectotypes and annotations included in herbarium packets. Quality of the images ranges from good to excellent and they will be quite useful for identification purposes.

The late Danish mycologist, Jan Vesterholt, is included as an author even though he passed away in 2011. Shortly before his death, he provided Beker and Eberhardt with collections, databases, notes, drawings, and photographs that were of great value in preparation of the book. Vesterholt had studied Hebeloma for many years and authored The Genus Hebeloma (Volume 3 of the Fungi of Northern Europe series published by the Danish Mycological Society, reviewed in FUNGI 6[1], Spring 2013) and played an important role in encouraging and influencing Beker’s and Eberhardt’s work on the genus.

In Our Approach and elsewhere, Beker and Eberhardt do a rather nice job explaining their philosophy and how they go about their studies, which lends a personal feel to the book. Given the widespread perception of hebelomas as a “faceless and featureless collection of brownish mushrooms,” it is especially important to understand how the authors arrived at recognition of the species they accept. As they relate in the Foreword, after a presentation on Hebeloma given by Vesterholt at a British Mycological Society workshop, an attendee commented that “you might have just shown 30 pictures of the same species and we would have been none the wiser.” In their own words …

“One has to keep in mind that species are theoretical constructs, and their real life equivalents are populations of individuals. If new species are evolving, they evolve from a subgroup of individuals among a group of individuals, not from a single ancestor as a (phylogenetic) tree suggests. If captured while the speciation process is still ongoing, species will not be monophyletic, but paraphyletic.”

“Within our work, we have used various techniques to investigate the taxonomy of Hebeloma species and where their boundaries exist. Indeed we have made use of various species hypotheses, primarily: morphological, phylogenetic, and biological. Whenever possible, we have looked for agreement between all three. … As may be expected, we have had a number of occasions when the different species hypotheses are not in clear agreement.”

It should be obvious that this book represents a tremendous amount of work and will be extremely important for European mushroom hunters. But how valuable will it be for those of us in North America? The authors wisely restricted their treatment to European and North African species (83 of them, with an acknowledgment that there are undoubtedly more to be found, particularly in areas, such as many parts of eastern Europe, where they have done little collecting), with one exception (the North American H. incarnatulum). It has taken them over two decades to understand, as best they can, the European names and how they have been applied. Because they have not done that for the approximately 250 North American names, they felt it best not to include consideration of them. (Note that Beker has now turned his attention to North America and is soliciting collections from interested mushroom hunters [see article in The Mycophile 56(5), September-October 2016]). Experience with other genera suggests that many of the northern European species also will be found in North America, although it is unlikely that all will. The proportion of species that occur on both continents likely will decrease as one proceeds from north to south on both sides of the Atlantic Ocean. Thus, it is difficult to estimate just how many of our species will be identifiable using the book. However, it certainly provides an excellent comprehensive introduction to the genus and an example of how to go about studying it. So, even if we won’t necessarily be sure we have exact species matches, we often should be able to get into a not-too-large ballpark. Thus, those North American mushroom hunters who aspire to identify everything they find will find this book quite useful. Although not cheap, it provides very high poundage and information content per dollar and is well worth adding to your library.

— Review by Steve Trudell
— Originally published in Fungi