This volume presents three extensive papers on Lentinellus KARSTEN, a mushroom genus especially rich in species in Europe and North America, its taxonomy, morphology, biogeography and phyologeny, the latter based on ribosome sequences.
Lentinellus is summarized based on worldwide collections. Twenty-four species are accepted. Nomina incertae sedis, Species Rejicienda, studies of type specimens and problems of typification are included topics. One species (L. castoreus) is reported as cosmopolitan, two appear to be circum-North Temperate (L. micheneri, L. ursinus), two are Gondwanan (L. novae-zelandiae, L. pulvinulus); the distribution of all others is restricted.
Type specimens representing names originally described or recombined in Lentinellus are examined macro- and micromorphologically. Such studies help to stabilize the use of names, and more accurately place the type specimen within the range of characters for the appropriate taxon.
A phylogenetic reconstruction of Lentinellus based on sequences of ribosomal ITS1-5.8S-ITS2 DNA is offered. Several infrageneric clades are identified, with some species well-separated (i.e. L. ursinus, L. castoreus, L. auricula, L. cochleatus), while several species separable on morphological and/or sexual distinctions appear grouped together (i.e. L. micheneri, L. subaustralis, L. flabelliformis, L. montanus, etc.). More robust phylogenies of L. castoreus and L. ursinus are described, as are possible origins of these species.
The volume is augmented by thirteen color plates.

Key words: Nomenclature, Names, Morphology, Taxonomy, Russulales, Lentinellaceae, Biogeography, Key. Phylogeny, DNA sequences, phylogeography.

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A Preliminary Monograph of Lentinellus (Russulales). By Ronald H. Petersen & Karen W. Hughes. March 2004. J. Cramer in der Gebr¸der Borntraeger Verlagsbuchhandlung, D-14129 Berlin. [Bibliotheca Mycologica No. 198.] Pp. 268, figs 51, tables 18, col. plates 13. ISBN 3 443 59100 0. Price Ä 80. As leader of the London Fungi Recording Group, in the autumn of 2003 I collected a species of Lentinellus from Epping Forest, to the north of London. Upon examining the collection both macro- and microscopically, it soon became apparent to me how difficult it was to assign this particular specimen to a species utilising personal and available literature in the library at the Royal Botanic Gardens Kew.

The species I collected was eventually named as L. ursinus, but to my mind and others, certain macroscopic features didn't seem to fit with L . ursinus, so a nagging uncertainty surrounded my collection.

Upon a recent visit to David Hawksworth, who knew of my problem, I was presented with this new preliminary monograph of the genus Lentinellus to utilise and then review. The monograph accepts 24 species, based on a study of worldwide collections.

The introduction to the monograph includes an engrossing section on the historical lineage of Lentinellus, leading to the molecular discovery of an evolutionary connection between Lentinellus and the Russulaceae ó fascinating stuff, but the amateur mycologist will need a copy of Ainsworth & Bisbyís Dictionary of the Fungi by their side to decipher some of the terms. The taxonomic characters of Lentinellus are dealt with fully in descriptions and line drawings, making the inherent characteristics of particular species clear and easy to follow. Materials and Methods, along with microscopic techniques are given in this section, also giving a good explanation on how the authors reached their conclusions. Hemicybe continues to be treated as a synonym. The key is a simple dichotomous one that is easy to follow.

The descriptions of the accepted species, including cultural morphology and sexual mating compatibilities, are presented in depth, complete with diagrams of microscopic features and colour plates which cover 16 species. There is an excellent commentary section accompanying each species, outlining important information. Many species are lecto-, neo-, or epitypified for the first time. The inclusion of a table of spore statistics for each species as given by different authors and from different collections is also a most useful feature. I also welcomed the reproduction of copies of original illustrations of the species. The copy of Sowerbyís illustration of the species now called L. vulpinus (originally described from north London) and the detailed notes on smell leave us in no doubt that this was the species we had from Epping Forest.

Going by own experience with the genus Lentinellus, this monograph gives an excellent insight into the genus and will prove to be a valuable addition to the growing number of modern generic revisions. Its depth and clarity make it a model to be emulated by others undertaking revisions of macromycete genera.

ANDY S. OVERALL

Mycotaxon 89(2) 2004

This volume of the well-known series comprises three parts: first a monographic treatment of the genus Lentinellus, secondly a chapter on type studies in Lentinellus, and finally a phylogenetic reconstruction of Lentinellus, using molecular markers. As such this can be considered a modern monograph.

The monographic part contains a key and descriptions of 24 species, preceded by chapters on the historic lineage of the genus, a discussion on the taxonomic relevant characters and the material and methods used. The nomenclature is extensive and upto- date and the lengthy descriptions are accompanied by line-drawings of good quality, and lists of the studied collections. Information on sexual compatibility, when available, is also provided.

The type studies are very comprehensive and detailed, with comments on the taxonomic status of the taxa. The phylogenetic reconstruction based on ribosomal ITS1- 5.8S-ITS2 sequences gives way to speculations about species concepts and relationship between certain groups. Some morphological species appear to be well supported, in other words the phylogeny is not very resolved, and several species which are well separable on morphological grounds and / or sexual distinctions group together. It is obvious that more work needs to be done with more data and more genes to resolve the taxonomy of these groups. The more robust phylogenies of L. castoreus and L. ursinus reveal biogeographic differences between populations and possible geographic origin of these species.

This monograph is very well conceived and warmly recommended.

Machiel Noordeloos

PERSOONIA - Vol. 19, Part 1, 2006

The present volume is a specialist’s work. The genus Lentinellus was erected in 1879 by Karsten to include stipitate, agaricoid or omphaloid basidiomata and excluded pleurotoid forms, which were placed in Hemicybe. Saccardo did not recognize Lentinellus and placed Karsten’s genera in Lentinus Fr. However, Singer recognized seven species. Recently (1999) Moreau et al. published a floristic monograph of European Lentinellus. The three chapters of the monograph reviewed here by Petersen & Hughes recognize 24 species within the genus, which they place in the Lentinaceae. The first chapter is a biogeographic survey with presentation of morphological descriptions, ability to interbreed (biological species concept) and occasional reference to nucleic acid sequences across species (phylogenetic species concept sensu Taylor). This chapter includes a dichotomous key to the species organized by micromorphological and geographical data; the latter seems strange to include as a key character. A synoptic key might have been more useful. Macromorphological variation within most of the species is quite high and can misled the unwary. The diagrammatic representation of intercollection compatibilities is an exceptionally clear and useful depiction of the authors’ fertility experiments; crosses among single basidiospore isolates show most species have a tetrapolar mating system.

The second chapter presents full descriptions of the type specimens. Because several of these collections are in poor condition, the uniformity of their annotation should retard further deterioration, thus this chapter should prove useful to whoever may choose to monograph the genus in the future.

The third chapter presents cladistic analyses of the genus based on ITS sequences of the large ribosomal subunit for 15 biological or morphological Lentinellus taxa; 11 were clearly delineated. With the full data set, the PAUP program was limited to 10,000 trees and 10,000 equally parsimonious trees were obtained. While most taxa show strong congruence among the various species concepts, some taxa are problematic in this regard. The authors invoke several possible explanations for the disagreements: slower evolution of ITS sequences than genes affecting morphology; mutation in developmental genes with pleiotropic effects that leave ITS sequences unaffected; rare hybridization events followed by introgression of the ITS sequences into one of the parent populations. For several clades, correlations are derived between geographic and ITS sequence data. As with many studies based on single gene families, this contribution can only present tentative topologies for the observed diversity and will best serve as an indicator for groups that require further study.

The data presented in this volume are generally clear and of high quality. My only quibbles have to do with: 1) placement of the legend for the well-reproduced color plates was at the end of chapter 1, nearly 100 pages from the plates themselves; and 2) the unitless terms E and Em, found in several tables and that presumably represent ellipsoidity of spores are undefined. Again, this is a specialist’s monograph; it will be of interest to taxonomists working within the Russulales, but few others. It should find its place in mycological libraries and herbaria.

David S. Yohalem, Valby, Denmark

Inoculum 57 (2), April 2006, p. 13