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Mycoamaranthus cambodgensis

Mycoamaranthus cambodgensis (Pat.) Trappe, S. Lumyong, P. Lumyong, Sanmee & Zhu L. Yang

Index Fungorum number: 488788


Fruitbodies emergent or subhypogeous, 10–35 x 10–40 mm, subglobose or globose to irregular, bright chrome yellow to orange-yellow when fresh, when dried bright yellow to yellowish brown, felty-smooth to minutely scaly. Gleba white and soft in youth, becoming light brown with translucent lines and at maturity blackish brown and rubbery, with a basal pad concolorous with the peridium and sometimes prolonged a few mm as a pseudostipe, usually lacking a columella but sometimes with a narrow, gray-translucent, gelatinous dendroid columella; locules minute, irregularly shaped, at maturity filled with spores. Rhizomorphs abundant, emergent from base, concolorous with peridium. KOH non-reactive on peridium or gleba. Taste and odor not distinctive. Peridium with a yellow pigment immediately leached from peridial tissue when mounted in KOH, single-layered, 200–300 μm thick, of pale yellow, thin-walled hyphae 3–5 μm broad, compactly interwoven to subpericlinal near gleba, more loosely interwoven near peridial surface, with some adherent soil particles; clamp connections absent. Glebal trama of hyaline, multibranched hyphae 3–7 μm broad, in youth thin-walled and loosely interwoven, at maturity with walls gelatinous-thickened and forming a tightly constructed tissue; clamp connections absent. Basidia clavate, hyaline, (14)18–20(24) x (7)9–11 μm, 4-spored, sometimes 1-, 2- or 3-spored, sterigmata 4(6) μm long, tapered. Spores mostly ovoid but some nearly obpyriform or ellipsoid, hyaline in youth but by maturity brown, 11–14 x 7–10 μm excluding the ornamentation, mostly with hyaline pedicels 2(3) x 1 μm; spore walls 0.7–1 μm thick, with a narrow germ pore; ornamentation of crowded spines 0.5–0.7(1) x 0.2 μm embedded in a hyaline matrix; walls and spines hyaline and dextrinoid in youth, at maturity in KOH pale golden brown to brown singly, the spores brownish yellow to brown in mass.

Etymology: cambodgensis, “growing in Cambodia.”

Distribution and Habitat: tropical Queensland, Australia, Cambodia and Thailand, in wet forests of Eucalyptus spp. or dry forests of Dipterocarpaceae, sometimes fruiting on cut banks of roads through forests or in pots of tree seedlings in nurseries; mycorrhizal habit unknown. All developmental stages are edible.

Collections Examined: AUSTRALIA: Queensland: Atherton Tablelands, Davies Creek State Forest, Davies Creek Rd., 6 Mar. 1994, D. Arora, Trappe 13468 (OSC), 3 May 1988, P. Reddell (CSIRO H4032) and 5 April 1989, J. Trappe & N. Malajczuk (CSIRO H4347, CANB 401583); Mt. Windsor Tablelands, Davies Creek National Park, 3 Feb. 1992, B. Bayliss & N. Bougher (CSIRO H5468, CANB 401606); Platypus Creek, 2 May 1988, M. Amaranthus & R. Young (CMU 45352, CSIRO H4002: type of M. auriorbis); Red Rd, Tully Falls State Forest, 4 May 1988, M. Amaranthus, J. Trappe, C. Theorodou & M. Castellano, 4 May 1988 (CSIRO H4045, CANB 401582). CAMBODIA: Kampong Chhuong Forest Reserve, M. Potelot 178 (FH, type of Dendrogaster cambodgensis Pat.). THAILAND: Chiang Mai, Sanpatong District, Mae Wang, Conservation Forest, Sanpatong-Ban Guard Rd., 24 July 2002, S. Lumyong, P. Lumyong, R. Sanmee & Z. L. Yang (CMU 45205, HKAS 41949, OSC 81190); Chiang Mai, Muang District, Doi Suthep, near Royal Gardens, 15 Sept. 1995, M. Castellano, Trappe 17517 (CMU 45348, HKAS 42378, OSC 81186); Chiang Mai, Jom Tong District, Doi Inthanon National Park, Mae Chaam Rd., ± 8 km from checkpoint 2 on main National Park Hwy., 25 Jan. 1994, T. Lebel, Trappe 13331 (CMU 45343, HKAS 42379, OSC 81180); 9.3 km from checkpoint 2 of main National Park Rd. 25 Jan. 1994, 25 June 1994, T. Lebel, Trappe 13335 (OSC 81181); Krabi, Khlong Tong District, Khao Bang Khram Non-hunting Area, Khao Nor Chuchi Lowland Forest Project, Field Station Nursery, 28 June 1994, J. Trappe 13338 (CMU 45344, HKAS 42387, OSC 81182) and T. Lebel, Trappe 13339 (OSC 81183); Satun, Muang District, ThaleBan National Park, 29 June 1994, M. Castellano, Trappe 13346 (CMU 45345, HKAS 42382, OSC 81187), L. Lebel, Trappe 13347 (CMU 45346, HKAS 42383, OSC 81184) and T. Lebel, Trappe 13348 (CMU 45347, HKAS 42386, OSC 81185); Yasothorn, Muang District, purchased in market, Oct. 1991, N. Ruangrungsi, Trappe 28046 (CMU  45350, HKAS 42381, OSC 81189).

Fig. 1 Mycoamaranthus cambodgensis (Pat.) Trappe, S. Lumyong, P. Lumyong, Sanmee & Zhu L. Yang (CMU 45205). 1. Basidiomes at different stages of development and their longitudinal sections. 2. Hymenium at a young stage. 3. Hymenium with basidia at different stages of development. 4. Spores.



Lumyong S, Sanmee R, Lumyong P, Yang ZL. et al. 2003 – Mycoamaranthus cambodgensis comb. nov., a widely distributed sequestrate basidiomycete from Australia and southeastern Asia. Mycological Progress 2, 323325.



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