This File Was Created by Scanning the Printed
Total Page：16
File Type：pdf, Size：1020Kb
Mycoiogia, 104(1),2012, pp. 164-174. DOl: 10.3852/11-046 1;') 2012 by The Mycological Society of America, Lawrence,KS 66044-8897 Cryptolepiota, a new sequestrate genus in the Agaricaceae with evidence for adaptive radiation in western North America Bradley R. Kropp! although G. clelandi subsequently was transferred to Department of Biology, 5305 Old Main Hill, Utah State the monotypic genus Horakiella by Castellano and University, Logan, Utah 84322 Trappe (1992). A few years later Gigasperma amer Steve Albee-Scott icanum Kropp and Hutchison was added to the genus Environmental Sciences, jackson Community College, so that it currently contains two species, G. cryptica 2111 Emmons Road, jackson, Michigan 49201 and G. amencanum (Kropp and Hutchison 1996). Gigasperma crypticais known only from New Zealand Michael A. Castellano where it occurs with species of Nothofagus (Castellano United States Department of AgricuituTe, Forest Seroice, and Trappe 1992). On the other hand, Gigasperma Northern Research Station, Forestry Sciences Laboratory, far Corvallis, Oregon 97331 anrencanumthus has been found only in the western United States. It is rarely collected and occurs in stands James M. Trappe of Cercocarpus ledifolius Nutt., a shrub or small tree in Department of Forest Ecosystems and Society, Oregon the Rosaceae that grows in semi-arid habitats through State University, Corvallis, Oregon 97331 out much of western North America. Because C. ledifolius is one of the Rosaceae that form ectomycor rhizas Kropp and Hutchison (1996) suggested that G. Abstract: Phylogenetic analyses based on nLSU and aJnericanum might be ectomycorrhizal, although this ITS sequence data indicate that the sequestrate genus has not been demonstrated experimentally. Gigasperma is polyphyletic. Gigasperma cryptica, which Despite the fact that both Gigasperma species are is known only from New Zealand, has affinities with hypogeous and have a similar spore morphology, the the Cortinariaceae whereas G. americanum and two enormous geographical distance separating their additional undescribed taxa from western North populations raises doubts about their relatedness. America are derived from Lepiota within the Agarica Moreover collections of additional, potentially unde ceae. The three North American taxa appear to be scribed material that shared morphological affinity recently evolved and are closely related. They occur with Gigasperma indicate that evolutionary radiation in similar environments and form a well supported might have occurred within this group in western clade indicating that adaptive radiation has occurred North America. The objectives of this work were: within this group of fungi. An independent genus (i) to assess the monophyly of Gigasperma sensu lato with sequestrate fructifications, Cryptolepiota is pro and (ii) to describe the two new taxa from North posed to accommodate the three species in this clade. America and determine their phylogenetic positions. Cryptolepiota microspora and C. mengei are described as new, and G. americanum is transferred to Crypto MATERIALS AND METHODS lepiota. Gigasperma crypticais illustrated and compared with the species of Cryptolepiota. Microscopic features were measured from material mount Key words: Basidiomycota, Cortinariaceae, fungi, ed in Melzer's reagent with oil immersion at 1000X, and Gigasperma, phylogenetics photomicrographs were taken with interference contrast. Spore measurements are reported as averages (20 spores) and ranges, whereas measurements for the spore wall and INTRODUCTION the other cells are giyen as ranges. Spore dimensions are given as length then width. The genus Gigasperma was erected by Horak (1971) DNA was extracted with the method of Kropp et aL to accommodate two sequestrate fungi from Tasma (1996). Briefly, dried herbarium material was cmshed in nia and New Zealand. Gigasperma is characterized liquid nitrogen before being mixed with an extraction by its hypogeous habit and distinctive smooth, buffer (0.7 M NaCl, 0.05 M Tris-HCL [pH 8], 0.01 M EDTA, subglobose to globose, thick-walled basidiospores. As 1 % (3-mercaptoethanol, 1% CTAB) and incubated at 60 C. proposed by Horak, the genus comprised two taxa, The mixture was emulsified in chloroform : isoamyl alcohol G. cryptica Horak and G. clelandi (Rodway) Horak, (24 : 1 by volume) and centlifuged. The DNA was precip itated from the supernatant with cold isopropyl alcohoL Submitted 1 Feb 2011; accepted for publication 8Jun 2011. Standard PCR protocols were used to amplify the portion I Corresponding author. Tel: (435) 797-3738; E-mail: brad.kropp@ of the nuclear large ribosomal subunit (nLSU) between usu.edu primers LROR and LRS (Moncalvo et aL 2000, Vilgalys and 164 KRopp ET AL.: CRYPTOLEPJOTA GEN. NOV. 165 Hester 1990), and the internal transcribed spacer (ITS) also consistent overall with the findings of Matheny et al. was amplified between primers ITS4 and ITS5 (White et al. (2006), although there are differences in tree 1990). Direct sequencing of the PCR products was done topology, potentially because we sampled far fewer with primers LROR and LR5 for the nLSU and ITS4 and taxa than they did. ITS5 for ITS. The sequences used for the phylogenetic In our analysis the taxa we placed in C1yptolepiota analysis were obtained with dye terminator methods with an were divided by Lepiota erminea (Fr.) Gillet (FIG. 1), ABI 3730 DNA Analyzer and deposited in GenBank (TABLE I). although posterior probabilitysupport for this position Initial BLAST queries with sequences from the Gigaspemw of L. erminea in this clade was less than 90%. With species indicated that they belong to the agaricoid clade of further analysis the position of L. em�ineaappeared to Matheny et al. (2006). Thus, taxon sampling to assess the stabilize and all three Cryptolepiota species were monophyly of Gigasperma was focused on this clade with monophyletic with good support. The clade compris members of the tricholomatoid clade of Matheny et al. (2006) ing Cryptolepiota is supported as being derived from being used to root the tree. To assess the phylogenetic Lepiota and the analysis also supports the proposition positions of the North American taxa relative to LejJiota, taxon that all three taxa are distinct species (FIG. 2). sampling was based on Vellinga (2004). The nLSU and ITS Even though the topology of our phylogram differs sequences for each sampled taxon were concatenated and somewhat from that published for Lepiota by Vellinga aligned with Clustal (Thompson et al. 1997). All taxa used in X (2003), the overall patterns observed in both studies the analysis were represented by both ITS and nLSU are consistent. In the analysis (FIG. 2) we recovered sequences (TABLE I). Alignments are available in TreeBASE, accession number 11566. A total of 1819 characters was used clusters of Lepiota species corresponding to clades 1 to assess the monophyly of GigasjJenna (FIG. 1), and 1702 and 4 as well as to clades 2/3 combined by Vellinga characters were used to assess the position of the North (2003) with good posterior probability support. American taxa relative to the genus LejJiota (FIG. 2). The aligned dataset was analyzed with MrBayes 3.1 DISCUSSION (Ronquist and Huelsenbeck 2003). Tree searches were performed with a time reversible model of evolution Based on our phylogenetic analysis, the genus (Maddison 1994, Rodriguez et al. 1990) and a discrete Gigasperma as currently understood is polyphyletic. gamma distribution with six substitution types and some Gigasperma cryptica, which is known from New invariant sites (GTR+G+I) was assumed. Posterior probabil Zealand, has affinities to the Cortinariaceae, whereas ities were approximated by sampling every 100 trees G. americanum and two morphologically similar simulated with the Markov chain Monte Carlo method (MCMC). The initial runs were conducted with eight active undescribed taxa from North America belong in MCMC chains, heated at 0.2, and started with a randomly the Agaricaceae (FIG. 1). The three North American chosen neighbor joining tree. The first MCMC run was species are closely related and are recently derived iterated for 1 000 000 generations, and three subsequent from Lepiota clade 1 of Vellinga (2003) (FIG. 2). MCMC simulations were done with 1000 000 generations, We propose the genus Cryptolepiota to accommo sampling every 100th tree. A majority consensus tree was date the North American taxa. The three Cryptolepiota calculated from the last 7000 sampled trees from a 10 000- species share unique ecological and morphological tree dataset using all runs to recover the posterior proba attributes and form a monophyletic lineage that bilities of the internal nodes with the SUlvIT command in appears to represent radiation within Lepiota. Crypto MrBayes. The results showed the convergence of two lepiota is the result of budding, the divergence of a independent MCMC chains as described in (Ronquist and new lineage from an extant parental taxon (Mayr and Huelsenbeck 2003) with a standard deviation between the Bock 2002). As a taxon Cryptolepiota differs sharply two independent chains less than 0.001. The potential scale reduction factors for all convergence statistics approached from its parental taxon macroscopically, microscopi 1.001 for all parameters. Posterior probablitility support cally and in its dispersal ecology, indicating that measures for nodes with less than a 90 percent posterior significant evolutionary change has taken place. The probability support are not shown. use of an independent