Agrocybe praemagna is described as a new species occurring in open alpine (occasionally also subalpine) habitats of the Rocky Mts., USA. Based upon relevant literature records a summary of Agrocybe species reported from alpine and arctic localities is presented

Horak, Egon

Moser, Meinhard M.

English

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Agrocybe praemagna: a new alpine species from Colorado, Idaho and Wyoming, Rocky Mountains, USA Meinhard M. Moser & Egon Horak Abstract Moser, Meinhard M. and Horak, Egon 2006. Agrocybe praemagna: a new alpine species from Colorado, Idaho and Wyoming, Rocky Mountains, USA. -Meddelelser om Grr,mland, Bioscience 56, Copen-hagen, The Commission for Scientific Research in Greenland, p. 133-138. Agrocybe praemagna is described as a new species occurring in open alpine (occasionally also subalpine) habitats of the Rocky Mts., USA. Based upon relevant literature records a summary of Agrocybe species re-ported from alpine and arctic localities is presented. Keywords: Agrocybe praemagna spec. nov., Basidio-mycota, Agaricales, arctic-alpine habitat, Rocky Mts., USA. Meinhard M. Moser, Mikrobiologisches Institut, Uni-versitat, Technikerstrasse 25, A- 6020 Innsbruck, Austria. Egan Horak, Nikodemweg 5, AT-6020 Innsbruck, Austria. Introduction In the last few years we observed close to or above tim-ber line at several alpine localities of the Rocky Mts. (Colorado, Idaho, Wyoming) the rather large basi-diomes of a conspicuous Agrocybe growing in open tundra-like vegetation. Apart from the robust basi-diomes, this new species, Agrocybe praemagna, is cha-racterized by the complete absence of veil remnants (cortina, ring) both on stipe and surface of the pileus, the comparatively large basidiospores, the unusual shape of the cheilocystidia, the presence of pileocy-stidia and the occurrence in inhospitable habitats in the upper subalpine and alpine zone of the Central Rocky Mts., USA. Description of the new taxon Agrocybe praemagna M.M. Moser & E. Horak, spec. nov. (Figs. 1 -3) Pileus 50-100 (-150) mm latus, convexus, pulvina-tus vel obtuse umbonato-campanulatus, primo ad marginem estriatum incurvatus, albidulus, eburneus vel argillaceus, opacus, siccus, glaber minute fur-furaceus, velum nullum. Lamellae 80-100, usque ad 15 lamellulae, densae, emarginatae, latae, pallidae dein pallide armeniaco-alutaceae vel griseo-brunneae. Stipes 50-10(-140) x 10-15(-25) mm, cylindricus, atten-uatus apicem versus, albidulus vel pallide ochraceus, brunnescens ad basim, minute furfuraceus sed innate fibrillosus basim versus, saepe striato-sulcatus ad apicem, siccus, solitarius, solidus. Cortina et annulus desunt. Caro albidulus, immutabilis. Sapor odorque subfarinosi. Basidiosporae in cumulo fuscae, 13-18.5 x 7-9.5 µm, ellipsoideae, porn germinativo instructae, brunneae, !eves. Basidia 36-40 x 10-11 µm, 4-spora, fibulata. Cheilocystidia 30-55 x 12-16 µm, obtuse fusoideo-ventricosa vel subutriformia, pigmento brun-neo impleta, incrustatione subcrystallina vel amorpha ad apicem obtecta, hyalina, tenuitunicata. Pleurocy-stidia 38-42 x 12-16 µm, clavata vel vesiculoso-pedun-culata, hyalina, tenuitunicata, levia. Pileipellis ex cel-lulis cylindrico-clavatis et fusoideis (pileocystidia) eel-133 MEINHARD M. MOSER & EGON HORAK Fig. 1. Agrocybe praemagna (holotype). lulodermium formantibus, 12-40 x 4-rn µm latis, hyali­nis, haud gelatinosis, fibulatis. Ad terram nudam apri­camque inter detritum plantarum, in pratis alpinis rare subalpinis. America borealis, Wyoming: Sho­shone National Forest, E-side of1\vo Ocean Mountain, 7.Aug. 1997, leg. Moser 97-134 (Holotypus, IB).Pileus 50-rno mm diam., occasionally reaching up to 150 mm, broadly convex to pulvinate or obtusely umbonate-campanulate, margin at first incurved be­coming straight in age, with pale colors ranging from dingy whitish to ivory or alutaceous, sometimes with pale brownish spots and areas near the always non­striate margin, opaque when wet, dry, smooth at first, becoming minutely furfuraceous or suede-like with age, veil remnants at non-striate margin absent. -Lamellae up to 80-rno reaching stipe, up to 15 lamellu­lae, crowded, widely emarginate and decurrent with short tooth, up to 8(-rn) mm wide, at first pallid, then pale apricot-alutaceous, finally turning (grey-)beige or grey-brown with age, even edges concolorous. -Stipe 50-rno(-140) x rn-15(-25) mm, base slightly en­larged, dingy whitish to pale ochraceous, base becom­ing brownish with age, finely furfuraceous, apex often 134 striate-furrowed, downwards innate-fibrillose, dry, solid, solitary. Sclerotium absent. - Veil remnants (cortina or annulus) absent, also in button-stage of young specimens). - Context whitish, in pileus up torn mm thick above lamellae. - Taste mild, slightly farina­ceous. - Odor not distinctive or weakly farinaceous. -Chemical reactions on pileus: KOH negative. Spore print dark brown, nearly blackish brown. -Basidiospores 13-18.5 x 7-9.5 µm, ellipsoid, with large eccentric apiculus, germ pore distinctive, 1-3 µm wide, brown walls thick (up to 1 µm diam.), smooth. -Basidia 36-40 x rn-11 µm, 4-spored, clavate. - Cheilo­cystidia 30-55 x 12-16 µm, variable in shape ranging from bottle-shaped to fusoid-subulate (and then often constricted towards apex) or nearly utriform, often with (yellow-) brown content and sometimes amor­phous to subcrystalline incrustatation at apex, hya­line, thin-walled. - Pleurocystidia 38-42 x 12-16 µm, clavate to vesiculose-pedunculate, scattered, hyaline, thin-walled, smooth. - Pileipellis a celluloderm com­posed both of clavate cells intermixed with distinctly larger, fusoid, pileocystidia-like cells, 12-40 x 4-rn µm, hyaline, non-gelatinous walls thin, smooth, pigment Fig. 2. Agrocybe praemagna (ZT 7487). 1. Basidiomes (nat. size). 2. Basidiospores (x 2000). 3. Cheilocystidia (x 1000). Bar= 20 mm (1), 10 µm (2), 20 µm (3). absent. Hyphae of subcutis composed of irregularly entangled cylindrical hyphae, 6-ro µm diam. - Olei-ferous hyphae present. - Clamp connections present. Habitat: On soil in open habitats close to and above timberline, in mountain meadows and sage-brush heath, close to and above timber line. Not coprophilous. Material examined: USA: Wyoming, Shoshone National Forest, E-side of Two Ocean Mtn., in alpine meadow, about 2950 m alt., 7. Aug. 1997, leg. Moser 97-134 (Holotype, IB). Additional collections of A. praemagna from the Rocky Mts. (USA) : Wyoming: Teton National Forest, trail to Union Peak, among sagebrush, above 3000 malt., 23. Aug. 1991, leg. Moser, 91-301 (1B). Colorado: Sanatch AGROCYBE PRAEMAGNA: A NEW ALPINE SPECIES Range, Independence Pass, on S-exposed slopes N of Pass, 3700 m alt. , on acid soil in alpine meadow, 13. Aug. 1999, leg. Horak 7487 (ZT) . Idaho: Grand Teton Mts., Teton Co., N of Driggs, on loess-like soil near Populus tremelloides, about 2000 m alt., leg. Cripps (CLC 079) in Horak ZT 8810. Discussion Following the taxonomic concepts as proposed by Watling (1982), Singer (1986) and Horak (2005) , Agrocybe praemagna belongs to sect. Pediadeae which encompasses species whose basidiomes are character-ized by the lack of persisting veil remnants, presence of pleurocystidia and comparatively large basidio-135 MEINHARD M. MOSER & EGON HORAK spores exceeding 12.5 µm in length. The presence of distinctive fusoid and pileocystidia-like cells in the pileipellis indicate, however, that taxonomically A. praemagna is also leaning towards species accomo-dated in sect. Microsporae. The present new species is distinctly characterized by the remarkably large basidiospores, the complete absence of veil remnants (even in button stage), the lack of a sclerotium at the base of the stipe and the typ-ical habitat in open, wind-exposed and rather dry localities in the (subalpine to) alpine zone beyond tim-berline. The four recorded collections of Agrocybe praemagna were exclusively found on (often bare) soil among rotting plant debris of the surrounding vegeta-tion. Thus it can be concluded that within the genus Agrocybe this species ecologically belongs to the group of the non-coprophilous representatives. In several alpine localities of Wyoming, basid-iomes of the present species have repeatedly been observed, but unfortunately no specimens were pre-served. Accordingly, it is expected that this conspicu-ous agaric is widely distributed in the Rocky Mrs. One possible reason why Agrocybe praemagna was not discovered yet in North America (Murrill 1917, Flynn and Miller 1990) is the fact that the basidiomes of this species can readily be confused with those of 136 2 3 Fig. 3. Agrocybe praemagna . 1. Basidiospores (holotype, x 2000) . 2. Pileipellis (x 500, vertical section, ZT 7487) . 3. Basidia (x 1000, ZT 7487). 4 . Pleurocystidia (x 1000, ZT 7487). Bar= 10 µm (1), 40 µm (2), 20 µm (3, 4). the widely distributed A. praecox (Pers.: Fr.) Fayod or A. dura (Bolton: Fr.) Singer. As a matter of fact at Independence Pass (in about 3700 m) A. praemagna was observed together with A. praecox at the same locality (Table 1). The large basidiospores of Agrocybe praemagna are a principal microscopic character to separate this species from related taxa whose basidiospores also exceed 10 µm in length. In the course of our studies we discovered also one population (IB 91 -301) with basidiospores slightly smaller than measured in the type material viz. 12.5-16 x 7-8.5 µm. This data, how-ever, still fall inside the range of spore size variation and accordingly this collection is considered a mere local ecotype of A. praemagna. Further significant microscopic features of A. praemagna are the distinctive thin-walled cheilocys-tidia with (yellow-)brown plasmatic pigment and amorphous to subcrystalline incrustation at the apex, and the hymeniform pileipellis composed of both clavate and fusoid cells. In the course of evaluating the taxonomic position of Agrocybe praemagna (Watling and Gregory 1981, Watling 1982), we found that Flynn and Miller (1990, and pers. comm.) refer to a species of Agrocybe (A. montana, nom. prov.), originally collected in sub-AGROCYBE PRAEMAGNA: A NEW ALPINE SPECIES Table 1. List of Agrocybe species reported from arctic-alpine, tundra or paramo habitats (including additional unpublished records from the Rocky Mountains). A. arenaria A. erebia A. muscigena A. paludosa A. pediades A. praecox Russia: Pamir, 2800 malt. (Kalamees 1989) Russia: Siberia: tundra, sea level (Lebedeva 1927) France: Savoyan Alps, 2320 malt. (Remy 1964) Russia: Taimyr: tundra, sea level (Tomilin 1971, Vasilkov 1971 ); Khibini Mts. (Mikhailovsky 1975) Scotland (Watling 1987) Switzerland: Grisons, 2400 malt. (Senn-lrlet 1992) Greenland: tundra, sea level (Rostrup 1891) Switzerland: Wallis (Boudier and Fischer 1895) Canada: Axel Heiberg Is., tundra, sea level (Parmalee 1963) Faeroer: pastures (M0ller 1945) Russia: Taimyr, tundra, sea level (Stepanova and Tomilin 1973); Khibini Mts. (Mikhailovsky 1975) Svalbard: tundra, sea level (Ohenoja 1971, Gulden 1996) New, unpublished records: USA: Colorado: Independence Pass N: tundra with dwarf and shrubby willows, 3700 malt., 11 A. praecox var. cutifrada A. semiorbicularis A. semiorbicularis var. caerulescens A. sphaleromorpha Aug. 1999, Horak 8119 (ZT) . - Same locality: tundra with dwarf and shrubby willows, 3700 malt., 13 Aug. 1999, Cripps 1366 (MONT). USA: Montana: Beartooth Mts., Plateau N, tundra with dwarf and shrubby willows, 3280 m alt., 22 Jui. 1999, Cripps 1289 (MONT). Venezuela: Andes, Paramo, 3560 malt. (Dennis 1960) Greenland: Kingitok, tundra, 550 m (Rostrup 1891) Jan Mayen: tundra, sea level (Hagen 1950) Faeroer: pastures, sea level (M0ller 1945) Russia: Caucasus, 2750 m alt. (Onipchenko and Kaverina 1989) alpine habitats in Canada (Alberta) and the USA World-wide, references of Agrocybe occurring in (Montana, Oregon, California), which also has rela- arctic-alpine, subantarctic (Horak 1982), tundra or tively large basidiomes. However, by comparison this paramo habitats are relatively scarce and often con-yet undescribed Agrocybe is characterized by distinctly cern only fimicolous or paludicolous species which, smaller basidiospores measuring only 8-12 x 5.6-6(-8) however, are characterized by a rather wide ecological µm . In addition, this taxon differs from A. praemagna range. The ten taxa of Agrocybe found in the pertinent by the color of the basidiomes, distinctive veil rem- literature are enumerated in Table 1. nants and its occurrence in subalpine conifer forests. In order to ascertain that these two sympatric taxa are actually not conspecific, related at subspecific level (ecotype) or intergrading, somatic compatibility tests in the laboratory of Prof. O.K. Miller (Blacksburg, USA) have been carried out. As expected from mor-photaxonomic evidence, it eventually turned out that the mycelia are incompatible and accordingly two dis-tinctive species are involved. Acknowledgements The authors are grateful to Dr. C. Cripps (Bozeman, MO, USA) for additional material and to Prof. O.K. Miller (Blacksburg, VA, USA) both for the compatibili-ty tests carried out in his institute and data about Agrocybe occurring in the USA. 137 MEINHARD M. MOSER & EGON HORAK References Boudier, E. and Fischer, E. 1895. Rapport sur Jes especes de champignons trouvees pendant l'assemblee a Geneve et Jes excursions faites en Valais par les Societes de Bota-nique de France et de Suisse du s au 15 aout 1894. -Bulletin de la Societe Botanique de France 41: 237-249. Dennis, R. 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Agrocybe praemagna; a new alpine species from Colorado, Idaho and Wyoming, Rocky Mountains, USA

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Agrocybe praemagna; a new alpine species from Colorado, Idaho and Wyoming, Rocky Mountains, USA

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