Genera in the Family Agaricaceae: Evidence from Nrits and Nrlsu Sequences
Total Page：16
File Type：pdf, Size：1020Kb
Mycol. Res. 108 (4): 354–377 (April 2004). f The British Mycological Society 354 DOI: 10.1017/S0953756204009700 Printed in the United Kingdom. Genera in the family Agaricaceae: evidence from nrITS and nrLSU sequences Else C. VELLINGA Department of Plant and Microbial Biology, University of California at Berkeley, 111 Koshland Hall no. 3102, Berkeley, CA 94720-3102, USA. E-mail : [email protected] Received 25 August 2003; accepted 25 January 2004. The circumscription of the family Agaricaceae, its genera and their characters are investigated. Analyses of the ITS and LSU sequence data, separately and in combination result in exclusions and reorganization. Notholepiota areolata, a secotioid species from New Zealand, Cystoagaricus with brown, irregular-knobby spores, and Leucopholiota with gelatinized hymenophoral trama and amyloid spores, fall outside the family Agaricaceae. In the reorganization, long accepted tribe and genus definitions are amended, viz.: (1) Macrolepiota and Chlorophyllum separately are monophyletic, but not together; (2) Leucoagaricus and Leucocoprinus together form one large monophyletic clade, that also includes polyphyletic Sericeomyces; (3) Lepiota, Cystolepiota and Melanophyllum together form a monophyletic clade; (4) Secotiation has happened within several clades (e.g. Agaricus and Chlorophyllum), though not in the Leucoagaricus/ Leucocoprinus clade, nor in the lineage of Macrolepiota proper; gasteroid and most secotioid species in the course of adaptation acquire coloured spores; and (5) the monovelangiocarpic Chamaemyces fracidus appears to be basal to the family and provides clues to the morphology of the ancestral Agaricaceae. Trama and developmental characters characterize the different clades, whereas spore characters play a minor role. separate family Lepiotaceae for the white-spored taxa INTRODUCTION warranted? (3) Are the tribes, recognized on morpho- The family Agaricaceae is a widely distributed mono- logical characters, supported by molecular evidence? phyletic group of saprotrophic fungi that exhibits huge (4) Are the genera Lepiota, Cystolepiota, Leucoagaricus, diversity in spore colour, and in structure of the pileus Leucocoprinus, Macrolepiota, and Sericeomyces mono- covering. Agaricoid, as well as secotioid and gasteroid phyletic? And (5) What are the morphological charac- taxa are included; see Singer (1986) for agaricoid mem- ters which are important at the deeper levels of the bers, Redhead et al. (2001) for Coprinus s. str., and classification? Kirk et al. (2001), Kru¨ ger et al. (2001), and Moncalvo The family Agaricaceae in the morphological sense, et al. (2002) for gasteroid and secotioid taxa. i.e. restricted to taxa with an agaricoid habit, has been This paper sets out to examine the circumscription divided into four tribes (Singer 1986, Wasser 1993). of the family as a whole (which genera do belong to However, one of the tribes, Cystodermateae, was it, and which do not), the relationships among the excluded from the family on morphological grounds genera, and the characterization of the genera. The (Bas 1988), and later the exclusion was confirmed by study focuses on the lepiotoid taxa and the emphasis sequence analyses (Johnson & Vilgalys 1998, Moncalvo is on the non-secotioid and non-gasteroid, north- et al. 2002). The remaining tribes are: temperate members of the family with white spores. (1) Agariceae: characterized by a brown spore print, Many taxa exist in the family, especially in the tropics, a regular lamella trama, and the absence of clamp- with other character combinations than those covered connections; there is some evidence that the excep- here. To give just one example, Heinemannomyces is a tional Heinemannomyces with blue spores might belong Malaysian genus characterized by a cobalt blue spore to this tribe. Singer (1975) stated that the spore wall print (Watling 1999). was not metachromatic in Cresyl Blue. Representatives Some specific questions which are considered are: (1) of Agaricus subgen. Agaricus, Allopsalliota, Cystoagari- Do Leucopholiota, Cystoagaricus, Chamaemyces, and cus, and Micropsalliota, as well as the secotioid A. in- Notholepiota belong to the Agaricaceae? (2) Is a apertus (syn. Endoptychum depressum), Gyrophragmium E. C. Vellinga 355 dunalii and Longula texensis, were examined for the morphologically to the Leucocoprinus group or to present study. Chlorophyllum (viz. L. flammeatincta, L. humei); how- (2) Lepioteae: comprising species with a regular ever, the appropriate combinations had not yet been lamella trama and whitish spores that are not meta- made. chromatic in Cresyl Blue (but see p. 374). Some authors (e.g. Bon 1981, 1993), have included Melanophyllum, with coloured spores, in this tribe, while other authors MATERIAL AND METHODS have placed that genus close to Agaricus, (e.g. Kerrigan Material 1986, Singer 1986, Wasser 2002). Pegler (1986) con- sidered Melanophyllum part of tribe Cystodermateae. This study is based on 160 specimens representing Chamaemyces, Cystolepiota (including Pulverolepiota), ca 150 taxa. Sequences were derived from fresh and Lepiota (including Echinoderma), and Melanophyllum herbarium specimens or were retrieved from GenBank. were sampled for this study. Most collections originated in Europe or North (3) Leucocoprineae: containing taxa with a trabecular America; tropical regions and the Southern Hemi- lamella trama and a complex spore wall which some- sphere are strongly under-represented. Type species times has a germ pore, and is metachromatic in Cresyl of genera were included wherever possible, but this Blue; the spores are whitish, rarely green. Chloro- was not feasible for Cystolepiota and Micropsalliota. phyllum, Leucoagaricus, Leucocoprinus, Macrolepiota, A single taxon represents the Lycoperdaceae, a group of and Sericeomyces were sampled. ca 190 species, in the ITS and ITS-LSU analyses; nine Many authors (e.g. Moser 1983), followed Singer’s species are included in the big LSU data set. Limacella family concepts after they had appeared in an earlier glioderma was chosen as outgroup; several bolete edition of his synopsis of the Agaricales (Singer 1975). species served as an alternate outgroup for a separate However, Bon (1993) placed the two tribes Lepioteae LSU data set of 54 species to test the position of several and Leucocoprineae in a separate family, Lepiotaceae, species formerly assigned to the family. Sequences of which he distinguished from the Agaricaceae in the the species cultivated by the attine ants were taken from white, rarely green, spore print. Ballero & Contu (1991) GenBank. Additional GenBank sequences represent adopted the same family concept, while deviating from unidentified Central American taxa, for which mor- all other contemporary authors in regarding Macro- phological data are lacking. In a few cases the ITS- lepiota as a synonym of Lepiota.Ju¨ lich (1982) raised sequence was taken from a different specimen than the the three tribes to the rank of family, and this concept LSU-sequence (see Table 1 for collections and species was followed by Grgurinovic (1997); Ju¨ lich (1982) analysed). also treated secotioid genera in families of their own Most of the sequences obtained from GenBank (Podaxaceae, Montagneaceae, Secotiaceae). were in the Agaricaceae and a few appeared to be mis- In previous molecular studies (Johnson & Vilgalys identified, based on sequence comparisons with the 1998, Johnson 1999, Moncalvo et al. 2002) it was present author’s data. Considerable effort was made to shown that Leucoagaricus and Leucocoprinus are not trace and examine the material on which the suspect jointly monophyletic, with L. flammeatincta and La. sequences had been based but this effort was not always rubrotinctus1 outside the clade made up of the other successful. However for non-lepiotaceous fungi the Leucoagaricus and Leucocoprinus species examined in identity declared in GenBank was not questioned. those studies. This clade also includes the taxa which are cultivated by the attine ants, and in which basi- Molecular identification diome formation is suppressed (Mueller, Rehner & Schultz 1998). DNA was extracted from fresh and herbarium Likewise, an analysis of LSU data (Moncalvo et al. material; the internal transcribed spacer (ITS), and 2002) indicated that the genus Lepiota does not form part of the large subunit (LSU) of the nuclear ribo- a monophyletic clade. This study assigned five species, somal repeat were amplified by the polymerase chain morphologically considered Lepiota (according to reaction (PCR) with the fungal specific primers ITS1F Singer 1986), to four different clades. It also found that and ITS4 (Gardes & Bruns 1993) for the ITS-region, Cystolepiota and Melanophyllum species, together with and primers LR0R, LR3R, LR7 and LR16 (www.bio- L. aspera (as L. acutesquamosa), form a clade separate logy.duke.edu/fungi/mycolab/) for LSU. Sequencing from the other Lepiota species. Two of the taxa used in of both strands was performed with an ABI model this study are designated Lepiota although they belong 377 sequencer or an ABI model 3100 automated sequencer (Applied Biosystems, Foster City, CA) using a Thermo SequenaseTM Dye terminator Cycle Se- 1 The following abbreviations are used throughout the paper to indicate genus names: Ag., Agaricus; Ch., Chamaemyces; Chl., quencing Pre-Mix Kit (Amersham Pharmacia Biotech, Chlorophyllum; Cl. Cystolepiota; L., Lepiota; La., Leucoagaricus; Piscataway, NJ) or a BigDyeTM Terminator Cycle Lc., Leucocoprinus; M., Macrolepiota; Me., Melanophyllum.