Brian P. Looney

Into and out of the tropics : global diversification patterns in a hyperdiverse clade of ectomycorrhizal fungi

Ectomycorrhizal (ECM) fungi, symbiotic mutualists of many dominant tree and shrub species, exhibit a biogeographic pattern counter to the established latitudinal diversity gradient of most macroflora and fauna. However, an evolutionary basis for this pattern has not been explicitly tested in a diverse lineage. In this study, we reconstructed a mega‐phylogeny of a cosmopolitan and hyperdiverse genus of ECM fungi, Russula, sampling from annotated collections and utilizing publically available sequences deposited in GenBank. Metadata from molecular operational taxonomic unit cluster sets were examined to infer the distribution and plant association of the genus. This allowed us to test for differences in patterns of diversification between tropical and extratropical taxa, as well as how their associations with different plant lineages may be a driver of diversification. Results show that Russula is most species‐rich at temperate latitudes and ancestral state reconstruction shows that the genus initially diversified in temperate areas. Migration into and out of the tropics characterizes the early evolution of the genus, and these transitions have been frequent since this time. We propose the ‘generalized diversification rate’ hypothesis to explain the reversed latitudinal diversity gradient pattern in Russula as we detect a higher net diversification rate in extratropical lineages. Patterns of diversification with plant associates support host switching and host expansion as driving diversification, with a higher diversification rate in lineages associated with Pinaceae and frequent transitions to association with angiosperms.

Lactarius subgenus Russularia (Basidiomycota, Russulales): novel Asian species, worldwide phylogeny and evolutionary relationships

Lactarius subg. Russularia is a large group of milkcaps occurring almost worldwide and dominant in many ecosystems. In this study we focus on new diversity, evolutionary relationships, divergence time, and origin of the subgenus. Six conifer symbionts are described as new to science: Lactarius atrii, L. aurantionitidus, L. dombangensis, L. flavigalactus, L. lachungensis, and L. sikkimensis. Species delimitation is assessed based on the concordance between morphological characteristics and an ITS phylogeny. Infrageneric relationships were studied using a phylogeny constructed from concatenated ITS-rpb2 data using Maximum Likelihood and Bayesian inference. Results show that species in this subgenus do not cluster together according to their geographic origin. Intercontinental sister relationships between Europe/Asia/North America are common but actual conspecificity is rare. This result suggests that allopatric speciation has played an important role within this subgenus. Only few morphological characteristics tend to be phylogenetically informative, with the most important being presence or absence of true cystidia and the pileipellis structure. Two datasets were generated in order to estimate the age of L. subg. Russularia. The results suggest the origin of L. subg. Russularia to be in the Mid Miocene period.

New insights in Russula subsect. Rubrinae: phylogeny and the quest for synapomorphic characters

Russula is one of the most speciose genera of mushroom-forming fungi, but phylogenetic relationships among species and subgeneric groupings are poorly understood. Our multi-locus phylogenetic reconstruction places R. firmula, R. rubra, R. rutila and R. veternosa in a well-supported Rubrinae clade, belonging to the Integrae clade of the Crown clade of the genus Russula. Traditional morphology-based classifications placed these four species in two different subsections based on the presence or absence of incrustations on pileocystidia. The Integrae clade also contains R. integra and related species that are traditionally placed in other groups based on their mild taste. Ancestral state reconstruction suggests that the common ancestor of the Crown clade and the Integrae clade probably did not have any incrustations in the pileipellis, had a mild taste, yellow spore print and were associated with angiosperms. All four species of the Rubrinae clade are defined by a darker yellow or ochre spore print, acrid taste and incrustations on pileocystidia. This last character contradicts the former splitting of the group because incrustations were apparently overlooked in R. firmula and R. veternosa. Incrustation type is now highlighted as being important for the delimitation of species and groups within the Crown clade. Pink or red staining of the incrustations in sulphovanillin is present in all species of the Rubrinae clade and a majority of the analysed species of the Integrae clade. The delimitation of the Rubrinae clade and its species circumscriptions are summarised here in a new diagnostic key.

Multilocus phylogenetic reconstruction of the Clavariaceae (Agaricales) reveals polyphyly of agaricoid members

The genus Camarophyllopsis contains species with lamellate (agaricoid) basidiomes in the family Clavariaceae (Agaricales), a group otherwise dominated by club-like (clavarioid) or branched (coralloid) forms. Previous studies have suggested that species classified in Camarophyllopsis occur in two independent lineages. We reconstructed a multilocus phylogeny of the Clavaria-Camarophyllopsis-Clavicorona clade in the Clavariaceae using RNA polymerase II second largest subunit (rpb2), nuclear ribosomal 28S, and nuclear ribosomal ITS1-5.8S-ITS2 regions data and detected three independent groups of agaricoid fungi, including the genera Camarophyllopsis, Hodophilus, and Lamelloclavaria gen. nov, which distinctly differ in their pileipellis structure. In all, nine major lineages within the Clavaria-Camarophyllopsis-Clavicorona clade were recovered: Clavaria sensu stricto, Camarophyllopsis sensu stricto, Hodophilus, the Clavaria pullei clade, the Clavaria fumosa clade, Lamelloclavaria gen. nov., the Clavaria atrofusca clade, Holocoryne (= Clavaria sect. Holocoryne), and Clavicorona. Clavaria is paraphyletic and represented by five clades. Additional gene sampling is necessary to determine and confirm relatedness of these lineages before splitting Clavaria into additional genera.

Circumscription of species in the Hodophilus foetens complex (Clavariaceae, Agaricales) in Europe

Four European Hodophilus species with an odour similar to naphthalene, a strong unpleasant odour similar to that of mothballs, are recognized based on sequence and/or morphological data. The traditional concept defines Ho. foetens as the only Hodophilus species with a naphthalene odour in Europe. This name is now assigned to one of the studied species based on morphological examination of the holotype specimen. A recently collected specimen is proposed as the epitype. The other three species with a naphthalene odour are described here as new: Ho. pallidus, Ho. subfoetens and Ho. tenuicystidiatus. They are distinguishable in the field based on a combination of lamellae number and colour of basidiomata. All four species are grouped in the Ho. foetens superclade, one of two superclades, together with the Ho. micaceus superclade, in the genus Hodophilus. All are different species from North American taxa with a naphthalene-like odour recognised in a previous study. The Ho. foetens superclade also includes one species identified as Ho. atropunctus that does not have a distinctive odour. The type collection of Ho. albofloccipes, a recently described European species with a naphthalene odour, is placed together with some collections without a distinctive odour in the Ho. micaceus superclade.

Hodophilus (Clavariaceae, Agaricales) species with dark dots on the stipe: more than one species in Europe

Hodophilus atropunctus is traditionally defined as the only species of this genus with dark brown or black dots on the stipe. Multi-locus phylogenetic reconstruction recognised two distinct clades morphologically corresponding to this species concept. The limited morphological description in the protologue of H. atropunctus and absence of a type specimen were limitations in an assignment of this name to one of the recognised phylogenetic species. The emended species concept and the selection of a neotype are based on careful analyses of the colour of the basidiomata and how this changes during maturation and drying. The name H. atropunctus is assigned to the paler of the two species which also shows colour change across the pileus and along the length of the stipe when dry. The second darker species is described here as new, H. variabilipes, but only seven out of 14 collections examined belonging to this taxon had distinct dark coloured dots on the stipe surface.