mycological research 110 (2006) 1409–1412 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/mycres Cantharellus pleurotoides, a new and unusual basidiomycete from Guyana5 Terry W. HENKELa,*, M. Catherine AIMEb, Heather MEHLa, Steven L. MILLERc a Department of Biological Sciences, Humboldt State University, Arcata, CA 95521, USA USDA-ARS, Systematic Botany and Mycology Lab, Beltsville, Maryland 20705, USA c Department of Botany, University of Wyoming, Laramie, Wyoming 82071, USA b article info abstract Article history: Cantharellus pleurotoides sp. nov. (Cantharellaceae, Cantharellales, Basidiomycota) is described Received 14 March 2006 from the Pakaraima Mountains of Guyana, occurring in rainforests dominated by ectomy- Received in revised form corrhizal Dicymbe spp. (Caesalpiniaceae). This fungus is singular among Cantharellus species 21 August 2006 described worldwide in possessing a pleurotoid basidioma. Macromorphological, micro- Accepted 1 September 2006 morphological, and habitat data are provided for the new species. Published online 22 November 2006 ª 2006 The British Mycological Society. Published by Elsevier Ltd. All rights reserved. Corresponding Editor: Michael Weiß Keywords: Basidiomycota Cantharellales Dicymbe Homobasidiomycetes Introduction Species of Cantharellus and Craterellus (Cantharellaceae, Cantharellales, Basidiomycota) are conspicuous components of the macromycota associated with ectomycorrhizal (EM) canopy trees of the genus Dicymbe (Caesalpiniaceae, tribe Amherstieae) in the primary rainforests of Guyana’s Pakaraima Mountains (Henkel et al. 2002). Ectomycorrhizal fungi fruit prolifically during the tropical rainy season in Dicymbe-dominated forests, while remaining largely absent from the surrounding mixed forest matrix composed of arbuscular-mycorrhizal trees. Eight years of collecting in this region have uncovered approximately 150 morphospecies of putatively EM fungi, a number of 5 which are new species and genera (e.g. Henkel 1999; Henkel et al. 2000; Miller et al. 2001; Simmons et al. 2001; Miller et al. 2002; Matheny et al. 2003; Henkel et al. 2005), while most still await formal description. Cantharelloid taxa occurring at the site include C. guyanensis and C. atratus, as well as three undescribed species of Craterellus. Here we describe an additional species, Cantharellus pleurotoides sp. nov., which is singular macromorphologically among Cantharellus species worldwide in possessing a pleurotoid basidioma with a smooth hymenophore. Cantharellus pleurotoides also has an unusual fruiting habit, the basidiomata arising in imbricate fashion at positions elevated from the forest floor on decayed woody substrata and humic deposits on the trunks of living trees. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. * Corresponding author. E-mail address: twh5@humboldt.edu 0953-7562/$ – see front matter ª 2006 The British Mycological Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.mycres.2006.09.010 1410 T. W. Henkel et al. Materials and methods Collections Collections were made during the May–July rainy seasons of 2000–2004 from the Upper Potaro River Basin, within a 5 km radius of a permanent base camp at 5 180 04.800 N; 59 540 40.400 W; elevation 710 m. The site was located in an undulating valley approximately 20 km east of Mt Ayanganna (2200 m), and was densely forested with a mosaic of primary Dicymbe-dominated and mixed forests of the Eschweilera-Licania association (Fanshawe 1952; Henkel 2003). All collections were made in forests dominated by Dicymbe corymbosa. Macroscopic features were described fresh in the field. Colors were described subjectively and coded according to Kornerup & Wanscher (1978), with color plates noted in parentheses. Macrochemical tests were performed according to the methods of Singer (1986). Fungi were field-dried with silica gel (Miller et al. 2002). Micromorphological features of fresh specimens were examined with an EPOI field microscope with light optics; dried specimens were examined with an Olympus BX51 microscope with light and phase contrast optics. For basidiospores, basidia, and other structures at least 20 individuals were measured. Rehydrated fungal tissue was mounted in H2O, 3 % KOH, and Melzer’s solution. Line drawings were made from digital photographs. Specimens were deposited in the following herbaria: BRG, University of Guyana; HSU, Humboldt State University; and BPI, US National Fungus Collections. Taxonomy Cantharellus pleurotoides T.W. Henkel, Aime & S.L. Mill, Figs 1–2 sp. nov. MycoBank no.: MB 510239 Etym.: Pleurotoides, Latin, referring to the distinctive pleurotoid basidiomata. Fig 2 – Microscopic features of Cantharellus pleurotoides (holotype, Henkel 8528). a. Basidiospores. b. Basidia with immature basidiospores. c. Hymenial elements. d. Tramal hyphae. e. Pileus trama and pileipellis. Bars [ 10 mm. Gregarius ad imbricatus in parvis gregibus in ligno carioso vel substrato humifero a solo in sylvis ectomycorhizalis Dicymbis corymbosae. Basidiomata pleurotoida, 7–23 mm lata, margine olivacea ad flava; hymenium albidum ad cineraceum, leave. Basidiosporae 8–10.5  6.5–8.5 mm, subglobosae, leaves, inamyloideae. Basidia (54)-60–72-(79) mm longa, apice 10–12 mm lata, basi 5–7.4 mm lata, subcylindrica; sterigmata 5–7 mm longa, basi 1.5–2 mm lata, cornuta, (3)-4–6 in quoque basidio. Cystidia ignota. Fibulae abundantes. Cantharellus pleurotoides diminutis pleurotoidibus basidiomatis et semper elevato fructificationis habitu a congeneribus diversus. Typus: Guyana: Region 8, Potaro-Siparuni: Pakaraima Mts, Upper Potaro River Basin, ww20 km east of Mt Ayanganna, 1 km N of base-camp along river east bank, alt. 710 m, in Dicymbe corymbosa forest, 28 June 2003, T. W. Henkel 8741 (BRG – holotypus; HSU – isotypus). Fig 1 – Basidiomata of Cantharellus pleurotoides (holotype, Henkel 8528). a. Development on decaying sapling trunk. b. Mature basidiomata on well-decomposed wood from tree trunk. Bars [ 10 mm. Basidiomata pleurotoid, generally dimidate to occasionally subflabelliform, 7–23 mm broad, astipitate or occasionally with a minute eccentric to lateral pseudostipe (Fig 1a,b); pileipellis olivaceous-yellow (3B8-3C8, 4C6-8), lightening to yellow (3A8) at extreme margin, moist, with short, erect strigose elements forming a whitish bloom throughout and a short projecting fringe at the margin; margin strongly incurved when young, becoming more upturned to irregularly and broadly Cantharellus pleurotoides, a new and unusual basidiomycete from Guyana wavy with age; hymenium covering entire lower surface, offwhite to light greyish (3B2-4B2), drying orangish-yellow (4A4-4A6), smooth, minutely hispid under lens, thickening slightly with age; context concolorous, soft, watery, unchanging. Taste and odour none. Macrochemical reactions: KOH and NH4OH nil on pileipellis and hymenium. Spore deposit not obtained. Basidiospores 8–10.5  6.5–8.5 mm (mean Q ¼ 1.3, n ¼ 20), subglobose, smooth, inamyloid, wall hyaline, contents a single large guttule, minutely and evenly granulose, pale yellow in KOH; hilar appendix 0.75–1 mm long (Fig. 2a). Basidia (54)-60– 72-(79) mm long, width at apex 10–12 mm, at base 5–7.4 mm, subcylindric, tapering evenly toward base, older basidia devoid of contents and hyaline, developing basidia with opaque, minutely granulose, light yellow contents, basal clamp connections occasionally observed; sterigmata 5–7 mm long, 1.5– 2 mm wide at base, cornute, (3)-4–6 per basidium (Fig. 2b). Basidioles numerous, with opaque light yellow contents in KOH (Fig. 2c). Cystidia not observed. Tramal hyphae tightly interwoven, branching frequently, hyaline to faint yellowish in KOH, moderately inflated, 6–13 mm wide, constricted slightly at septa, with minute granulose contents, wall 0.75–1 mm wide; clamp connections abundant (Fig. 2d). Pileipellis consisting of a subpellis arising anticlinally from tramal hyphae, with light yellow, opaque contents in KOH, these terminating in a suprapellis of anticlinal elements arranged in loose, irregular fascicles; terminal cells undifferentiated (Fig. 2e). Habit, habitat, and distribution. Gregarious to imbricate in small troops at positions elevated from the forest floor, on decayed woody substrata and humic deposits on the trunks of living trees. Infrequently encountered during the May–July rainy season in forests dominated by the ectomycorrhizal canopy tree Dicymbe corymbosa. Known only from the type locality in the Upper Potaro River Basin, Guyana. Additional specimens examined. Guyana: Region 8, Potaro-Siparuni: Pakaraima Mountains. Upper Potaro River Basin, w20 km east of Mt. Ayanganna, environs of base camp located on Potaro River one km upstream from confluence with Whitewater Creek: near Ayanganna Airstrip, on sticks in D. corymbosa forest, 20 May 2000, Aime 986 (BRG, BPI); Black Water Creek, gregarious on sticks, mosses, decaying wood, and living roots, in D. corymbosa forest, 9 June 2000, Aime 1171 (BRG, BPI); vicinity of Potaro base camp, 720 m elevation, in D. corymbosa forest, scattered on twigs, sticks, and sides of decomposed logs, 7 June 2002, Aime 1908 (BRG, BPI); vicinity of Potaro base camp, 720 m elevation, in D. corymbosa forest, 26 June 2001, Henkel 8382 (BRG, HSU), vicinity of Potaro base camp, 720 m elevation, in D. corymbosa forest, 13 June 2002, Henkel 8462 (BRG, HSU). Commentary. Cantharellus pleurotoides is recognized in the field by the small, olive-yellow pleurotoid basidiomata in small troops, sometimes nearly imbricate, on rotting sticks, logs, and elevated humus in Dicymbe corymbosa forests. The fungus could initially be mistaken for a discomycete, due to the cupulate appearance when young, but the downward-facing hymenium is telling. Currently, C. pleurotoides has been collected only in stands dominated by EM Dicymbe spp., suggesting an ectotrophic nutritional mode for the fungus, corroborated by the presumed EM status of other Cantharellus species. The small pleurotoid basidioma with smooth hymenophore of C. pleurotoides constitutes a singular macromorphology among Cantharellus species described worldwide (Heinemann 1411 1959; Corner 1966, 1969), although the incurved margin of the young pilei is consistent with that of other Cantharellus species (Corner 1966). Micromorphologically, the long, narrow basidia bearing 4-6 curved sterigmata, white, smooth, thin-walled, inamyloid basidiospores, and monomitic, inflated, regularlyclamped tramal hyphae are consistent with the placement of C. pleurotoides in Cantharellus. While clamp connections are known to occur in some species of the closely related genus Craterellus (e.g. C. tubaeformis), C. pleurotoides cannot be referred to Craterellus due to its lack of both a straight pileal margin when young and a membranous texture, the presence of which are diagnostic features for Craterellus in the traditional and modern senses (Corner 1966; Feibelman et al. 1997; Dahlman et al. 2000). Additionally, C. pleurotoides cannot be referred on morphological grounds to any resupinate taxa now known to occur in the cantharelloid clade as defined by molecular data (e.g., Botryobasidium, Sistrotrema; Binder et al. 2005). Cantharellus pleurotoides is inconsistent morphologically with Botryobasidium, species of which have short (<20 mm), cylindric to suburniform basidia, hyphae branching at right-angles, and resupinate basidiomata, and with Sistotrema, species of which have urniform or utriform basidia and are typically ampullate near the septa. The unusual pleurotoid basidioma nothwithstanding, we see no morphological reason not to ally C. pleurotoides with the Cantharellus/Craterellus/Hydnum clade, within which the taxon is best disposed in Cantharellus due to its fleshy, imperforate basidioma. Infragenerically, C. pleurotoides most closely fits in subgen. Cantharellus, sect. Cantharellus due to the brightly coloured basidiomata, regularly clamped hyphae, and lack of a regularly palisadic pileipellis (Corner 1966). Diminutive basidiomata characterize some species of Cantharellus, but in most cases the basidiomata differ from those of C. pleurotoides in being more or less centrally stipitate with the hymenium underlying an apical pileate portion, having well-developed hymenophoral folds, and a terrestrial fruiting habit. Stipitate Cantharellus species described with pilei <20 mm diam. appear to be entirely tropical and include the Congolian C. tenuis, C. alboroseus, and C. addaiensis (Heinemann 1959; Corner 1966), the Congolian/Tanzanian C. microcibarius. (Buyck et al. 2000), the Madagascan C. decolorans (Eyssartier & Buyck 1999), the Malaysian C. diminutivus and C. ianthinus (Corner 1966, 1969), and C. garnierii (Ducousso et al. 2004) from New Caledonia. Corner (1966) records two species from Brazil, C. fuscipes and C. reniformis with very narrow (<10 mm), reniform, yellowish pilei with short lateral stipes, but both of these species differ from C. pleurotoides in having distinct intervenose hymenophoral folds and short (<30 mm), 4-sterigmate basidia. Additionally, the Asian species C. furfuraceous, C. pusio, and C. merrillii approach the small, pleurotoid form but have distinct hymenophoral folds and short basidia (Corner 1966). As in C. pleurotoides, an extreme reduction in basidioma size combined with fruiting from elevated positions on humic substrata occurs in other ectotrophic basidiomycetes found in Guyanese Dicymbe forests, including the centrally stipitate Inocybe pulchella and I. epidendron (Matheny et al. 2003), Tylopilus exiguus (Henkel 1999), and Coltricia verrucata (Aime et al. 2002), and the pleurotoid Lactarius panuoides, L. brunellus, L. multiceps, and Russula campinensis (Henkel et al. 2002; Miller 1412 et al. 2002). Given the high precipitation occurring during the May–July rainy season (Henkel et al. 2002) and the great propensity for Dicymbe roots to explore and form ectomycorrhizas in suspended humus (Woolley & Henkel 2005), perhaps there were selection pressures for fruiting above the sodden conditions of the forest floor, for more effective aerial spore dispersal (Ingold 1965). Basidiomata in this case would no longer require the mycelial resources necessary to reach a size sufficient to rise above the litter layer; smaller basidiomata, with a higher hymenium area to mass ratio, would therefore be selected for. Acknowledgements This research was made possible by grants to TWH from the National Geographic Society’s Committee for Research and Exploration, the Smithsonian Institution’s Biological Diversity of the Guianas Program, the Linnaean Society of London, and the Humboldt State University Foundation. Additional support was provided by grants to S.L.M. from the National Science Foundation, DEB-0315607, USDA Competitive Grants 03-01542 and EPSCoR (0447681). The authors wish to thank Christian Feuillet for the Latin diagnosis. Field assistance in Guyana was provided by Mimi Chin, Christopher Andrew, Leonard Williams, Valentino Joseph, Francino Edmond, and Luciano Edmond. Research permits were granted by the Guyana Environmental Protection Agency. 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