Melanogaster coccolobae sp. nov. (Paxillaceae, Boletales), a tropical hypogeous fungus from the urban areas of Quintana Roo, Mexico

Background and Aims: The genus Melanogaster is characterized by its hypogeous to semi hypogeous habit, brownish basidiomata, gel-filled gleba locules, and globose to ellipsoid basidiospores. The genus is distributed in temperate zones, but sequences from Coccoloba root tips and a few basidiome collections have revealed its presence in the tropics. The aim of this article is to describe a new species of Melanogaster based on ecological, molecular, and morphological data. Methods: Specimens were collected in urban vegetation of Quintana Roo in the Yucatán Peninsula, Mexico. For morphological description, the classic protocols for sequestrate fungi were followed. The dried material was deposited in the mycological herbarium “José Castillo Tovar” of the Instituto Tecnológico de Ciudad Victoria (ITCV) and the herbarium of the Universidad Autónoma de Yucatán (UADY). Key results: Melanogaster coccolobae is presented as a new species from the urban gardens of Quintana Roo based on ecological, molecular, and morphological evidence. This species is characterized by its hypogeous to semi hypogeous basidioma, greyish orange, brown to reddish brown peridium composed of two layers, sweet smell, subglobose, ellipsoid or piriform basidiospores, and by its mycorrhizal association with Coccoloba spicata. Conclusions: Melanogaster coccolobae is the first species described from the Mexican Caribbean from urban gardens with Coccoloba spicata. More studies about the tropical sequestrate fungi are recommended.

Australasian sequestrate Fungi 20: Russula scarlatina (Agaricomycetes: Russulales: Russulaceae), a new species from dry grassy woodlands of southeastern Australia

Russula scarlatina sp. nov. is a common sequestrate fungus found in the dry sclerophyll Eucalyptus woodlands of southeastern Australia. Basidiomata are hypogeous or sometimes emergent; they are scarlet in youth and become dark sordid red or brown with advanced age. Historically, this species would have been placed in the genus Gymnomyces, but in light of recent revisions in the taxonomy of sequestrate Russulaceae, we place it in the genus Russula. It is morphologically distinct from other sequestrate species of Russula because of its scarlet peridium and unusual cystidial turf in youth. It has been collected only in dry grassy woodlands and open forest habitats of southeastern Australia.

A novel approach for tracing mycophagous small mammals and documenting their fungal diets

We developed a method combining passive baiting (animals that are not trapped) with DNA meta-barcoding of the feces acquired, to study fungi in the diet of small mammals. Mammal and fungal species were identified using genomic DNA of 596 fecal samples collected in five regions of the eastern Canadian boreal forest. For identification of the small mammal species, the cytochrome b region was used. A total of eight species of small mammals displayed hypogeous fungi consumption, with northern flying squirrels (Glaucomys sabrinus) and red-backed voles (Myodes gapperi) as the top consumers. For identification of their fungal diets, the ribosomal internal transcribed spacer (ITS) region was used. We recovered 722 taxa of Ascomycota, 429 Basidiomycota, 81 Zygomycota, 4 Chytridiomycota, 1 Glomeromycota, and 44 unidentified fungal taxa. Of these, 28 were hypogeous sequestrate fungi (underground fructification), which presumably are dug out by small mammals for consumption. Otherwise, for the remaining fungi [epigeous (above ground fructification) or microscopic fungal species], it is unclear which ones are selected by the animal as a dietary source or result from incidental contamination. Our paper presents a promising approach for tracing mycophagy in small mammals, and our results suggest that fungal diversity is important for the diet of some small mammals.

Lactarius taedae (Russulales): an unexpected new gasteroid fungus from Brazil

Data about the occurrence of basidiomata forming hypogeous sequestrate fungi in Brazil are limited, and studies on this group are needed. During studies of hypogeous sequestrate fungi in Rio Grande do Sul State, Brazil, an unexpected new species of Lactarius was sampled from soils of an exotic Pinus plantation and described based on molecular and morphological data. This new species is recognized by the reddish yellow to dark brown, hypogeous basidiomes with a persistent peridium, white unchanging latex, globose to broadly ellipsoid basidiospores that are ornamented with a complete and dense reticulum and the peridiopellis composed by a cutis of repent firmly woven hyphae.

Dating the emergence of truffle-like fungi in Australia, by using an augmented meta-analysis

Australia supports a high diversity of sequestrate (truffle-like) macrofungi. This has long been thought to be related to the predominantly or seasonally dry climate. The present study posits that if aridity were a key factor in the evolution of sequestrate fruit-bodies, most sequestrate species would have emerged in Australia only after it began to aridify, which occurred post-separation with Antarctica (c. 32 million years ago). Focusing on the high phylogenetic diversity of sequestrate taxa in the Agaricomycetes in Australia, dates of sequestrate nodes were compiled directly from published phylogenies (four lineages) or created using sequences available on GenBank that were processed in BEAST using a secondary calibration method (nine lineages). Although the morphologically diverse Hysterangiales was found to be the first group to become sequestrate, c. 83 million years ago, overall sequestration in Australia occurred more recently. Models were created and compared and support was found for an increased rate of sequestration in Australia at some point between 34 and 13 million years ago (during the Oligocene and Miocene). Although the rate of sequestration is shown to have increased in Australia after separation from Antarctica, the timing also overlaps with the radiation of potential mycorrhizal plant associates, and the emergence of specialised mycophagous marsupials. Although aridification is evidently not the sole driver of sequestration, it is still likely to have had a major influence on the diversity of sequestrate fungi in Australia. Comparisons with other regions of high sequestrate diversity will be informative.