Nian-Kai Zeng

DNA Sequence Analyses Reveal Abundant Diversity, Endemism and Evidence for Asian Origin of the Porcini Mushrooms

The wild gourmet mushroom Boletus edulis and its close allies are of significant ecological and economic importance. They are found throughout the Northern Hemisphere, but despite their ubiquity there are still many unresolved issues with regard to the taxonomy, systematics and biogeography of this group of mushrooms. Most phylogenetic studies of Boletus so far have characterized samples from North America and Europe and little information is available on samples from other areas, including the ecologically and geographically diverse regions of China. Here we analyzed DNA sequence variation in three gene markers from samples of these mushrooms from across China and compared our findings with those from other representative regions. Our results revealed fifteen novel phylogenetic species (about one-third of the known species) and a newly identified lineage represented by Boletus sp. HKAS71346 from tropical Asia. The phylogenetic analyses support eastern Asia as the center of diversity for the porcini sensu stricto clade. Within this clade, B. edulis is the only known holarctic species. The majority of the other phylogenetic species are geographically restricted in their distributions. Furthermore, molecular dating and geological evidence suggest that this group of mushrooms originated during the Eocene in eastern Asia, followed by dispersal to and subsequent speciation in other parts of Asia, Europe, and the Americas from the middle Miocene through the early Pliocene. In contrast to the ancient dispersal of porcini in the strict sense in the Northern Hemisphere, the occurrence of B. reticulatus and B. edulis sensu lato in the Southern Hemisphere was probably due to recent human-mediated introductions.

Molecular phylogenetic analyses redefine seven major clades and reveal 22 new generic clades in the fungal family Boletaceae

Mushrooms in the basidiomycete family Boletaceae are ecologically and economically very important. However, due to the morphological complexity and the limited phylogenetic information on the various species and genera of this fungal family, our understanding of its systematics and evolution remains rudimentary. In this study, DNA sequences of four genes (nrLSU, tef1-α, rpb1, and rpb2) were newly obtained from ca. 200 representative specimens of Boletaceae. Our phylogenetic analyses revealed seven major clades at the subfamily level, namely Austroboletoideae, Boletoideae, Chalciporoideae, Leccinoideae, Xerocomoideae, Zangioideae, and the Pulveroboletus Group. In addition, 59 genus-level clades were identified, of which 22 were uncovered for the first time. These 22 clades were mainly placed in Boletoideae and the Pulveroboletus Group. The results further indicated that the characters frequently used in the morphology-based taxonomy of Boletaceae, such as basidiospore ornamentation, the form of the basidioma, and the stuffed pores each had multiple origins within the family, suggesting that the use of such features for high-level classification of Boletaceae should be de-emphasized and combined with other characters.

The genus Phylloporus ( Boletaceae, Boletales ) from China: morphological and multilocus DNA sequence analyses

Species of the genus Phylloporus in China were investigated based on morphology and molecular phylogenetic analysis of a three-locus (nrLSU, ITS and tef-1a) DNA sequence dataset. Twenty-one phylogenetic species were recognized among the studied collections. Seven of them are described as new: P. brunneiceps, P. imbricatus, P. maculatus, P. pachycystidiatus, P. rubeolus, P. rubrosquamosus, and P. yunnanensis. In addition, four of them correspond with the previous morphology-based taxa: P. bellus, P. luxiensis, P. parvisporus, and P. rufescens. The remaining ten phylogenetic species were not described due to the paucity of the materials. A key to the Chinese morphologically recognizable taxa was provided. A preliminary biogeographical analysis showed that (1) Pylloporus species in East Asia and Southeast Asia are mostly closely related, (2) species pairs or closely related species of Phylloporus between East Asia and North/Central America are relatively common, and (3) the biogeographic relationship of Phylloporus between East Asia and Europe was supported by only a single species pair. Unexpectedly, no taxa common either to both Europe and East Asia, or to both East Asia and North/Central America, were uncovered. Clades look to have taxa from both sides of the Pacific and Europe/Asia though.

Molecular phylogeny and taxonomy of the genus Veloporphyrellus

Veloporphyrellus is a genus known from North and Central America, southeastern Asia, and Africa. Because species of this genus are phenotypically similar to some taxa in several genera, such as Boletellus, Leccinum, Strobilomyces, Suillus and Tylopilus s.l. belonging to Boletales, its phylogenetic disposition has never been addressed. We analyzed four DNA regions, the nuclear ribosomal LSU and tef-1α, and the mitochondrial mtSSU and atp6 genes, to investigate the phylogenetic disposition of Veloporphyrellus. Although the monophyly of the genus and its systematic placement within the Boletaceae was well supported, its relationship to other genera was not resolved. Morphologically Veloporphyrellus is distinguished from other boletoid genera by the combination of the pinkish or grayish pink hymenophore, the membranous veil hanging on the pilea margin, the trichoderm-like pileus covering and the smooth basidiospores. Five species, including two new species and two new combinations, are described and illustrated. A key to the species of Veloporphyrellus also is provided.

Four new genera of the fungal family Boletaceae

Based on our previous molecular phylogenetic analyses, four new genera are described, namely Baorangia, Lanmaoa, Parvixerocomus, and Rugiboletus, and one known genus, Neoboletus, is re-delimitated. Four new species and nine new combinations are proposed. Morphological characters of each genus and related eleven species are described and illustrated. Most of species in the genera described from southwestern China are wild edible mushrooms and can be found in free markets.

Notes on two species of Boletellus (Boletaceae, Boletales) from China

Based on studies of the types and additional materials, Boletellus emodensis and B. obscurecoccineus are described and illustrated in detail. Strobilomyces annamiticus is lectotypified and synonymized with B. emodensis; specimens from China regarded as B. ananiceps are confirmed to represent B. emodensis; B. puniceus and Boletus megasporus, originally described from southwestern China, are conspecific with B. obscurecoccineus.

Type studies on two species of Phylloporus (Boletaceae, Boletales) described from southwestern China

Type specimens of two Phylloporus species originally described from southwestern China were studied. The concept of P. luxiensis is refined with additional recently collected materials, while P. scabrosus is revealed to be a member of the genus Lentinus.

The genus Retiboletus in China.

Species of the genus Retiboletus (Boletaceae, Boletales) in China are investigated based on morphology and phylogenetic analyses of DNA sequences from nuc rDNA internal transcribed spacer (ITS) and partial 28S regions and sequences from the translation elongation factor 1-a gene (tef1a). Six lineages are recovered among the collections studied. Five of these are documented and presented in the present paper, including three new species and two new combinations. The remaining species is not described due to the paucity of material. The specimens from China identified as “R. ornatipes” or “R. retipes” are in fact R. sinensis or R. kauffmanii, those labeled “R. griseus” are either R. fuscus or R. pseudogriseus. A key to all known taxa of the genus is provided. Phylogenetic relationships of taxa within Retiboletus are partially resolved. A preliminary biogeographical analysis shows that allied species of Retiboletus between eastern Asia and North/Central America are common but there are no Retiboletus species common to both continents. Species of Retiboletus in Japan and southern China are conspecific or closely related.

A geographical extension of the North American genus Bothia (Boletaceae, Boletales) to East Asia with a new species B. fujianensis from China

Bothia fujianensis is described as a new species from Fujian Province, a subtropical region of China. It is morphologically characterized by its brown to pale reddish brown basidiomata, pale brown hymenophore, adnate to slightly decurrent, with subreticulations to ridges at the apex of the stipe, relatively longer pleurocystidia, and clavate, subclavate or ventricose cheilocystidia. Molecular phylogenetic analyses using the large subunit nuclear ribosomal RNA loci, DNA nucleotide sequences of the internal transcribed spacer region, and the translation elongation factor 1α also confirmed that B. fujianensis is distinct from B. castanella. The discovery of B. fujianensis in China indicates that Bothia has a much wider geographical distribution range occurring in East Asia and in North America.

The genus Pulveroboletus (Boletaceae, Boletales) in China

ABSTRACT Species of Pulveroboletus (Boletaceae, Boletales) in China are investigated on the basis of morphology and molecular phylogenetic analyses of DNA sequences from nuc rDNA region encompassing the internal transcribed spacers 1 and 2, along with the 5.8S rDNA (ITS) and nuc 28S rDNA D1–D2 domains (28S) and sequences from the translation elongation factor 1-α gene (TEF1). Nine species are recognized in the country, three of them are described as new: P. flaviscabrosus, P. rubroscabrosus, and P. subrufus, five of them are previous described taxa: P. brunneopunctatus, P. brunneoscabrosus, P. macrosporus, P. reticulopileus, and P. sinensis, the remaining one is tentatively named P. cf. ridleyi, which will be further studied in the future. A key to the Chinese taxa of the genus is provided. Unexpectedly, the current study did not identify disjunct populations of Pulveroboletus species in East Asia and North/Central America.