Phylogenetics - Fungi: Agaricus

1.Image analysis of Agaricus basidiospores
for use in systematics

A. D. Mitchell, M. Walter and R. E. Gaunt
Biotechnology Techniques. 11. 801-804.

Abstract: Basidiospore characters were measured using computer-based image analysis with greater speed (10x) and objectivity than possible manually. This technology allowed measurement of additional variables for studies of spores, including area and circularity, as well as length, breadth and elongation. Principal component analysis of basidiospore characters aided definition of species and species groups.

Agaricus arvenis

Agaricus arvensis. Painted by Marie Taylor at Whangarei Falls, 22.V.1992

Phylogenetic relationships of Agaricus species based on ITS-2 and 28S ribosomal DNA sequences

A. D. Mitchell and A. Bresinsky
Mycologia. 91: 811-819.

Abstract: Parsimony and maximum likelihood analyses of sequence data from the internal transcribed spacer (ITS-2) region plus a portion of the 28S gene are used to study the phylogenetic relationships of Agaricus species. The ingroup contained 16 Agaricus species, selected from the range of sections contained in the subgenus Agaricus. A total of eight outgroups were chosen from the Agaricaceae and phylogenetic trees rooted on Stropharia coronilla. Results suggest that Agaricus may be monophyletic, but further tests should include taxa from the subgenera Langagaricus and Conioagaricus. Two well-supported clades were found. The Agaricus clade contained A. subperonatus, A. devoniensis, A. bisporus, A. spissicaulis, A. bitorquis, and A. impudicus. Results suggest that A. bernardii may be closely related to this group. The Arvenses clade contained A. silvicola, A. arvensis, A. abruptibulbus, and A. semotus. A possible sister group to the Arvenses clade includes A. lanipes and A. maskae. Relationships for A. campestris, A. silvaticus and A. xanthoderma remain unclear, although it is likely these species diverged early compared with the other Agaricus species studied. Phylogenetic hypotheses are given for taxa that have been difficult to classify based on other forms of data, including the placement of A. spissicaulis with A. bisporus; A. lanipes with A. maskae.

Phylogenetic tree

Species of Agaricus occurring in New Zealand

A. D. Mitchell, M. Walter
New Zealand Journal of Botany. 37: 715-725

Abstract: A key is provided for 21 species occurring in New Zealand: Agaricus arvensis, A. augustus, A. bambusae var. australis, A. bernardii, A. bisporus var. bisporus, A. bitorquis, A. campestris var. campestris, A. campestris cf. var. floccipes, A. cupreobrunneus, A. horakii, A. impudicus (=A. variegans), A. lanatoniger, A. lanipes, A. meleagris, A. oligocystis, A. porphyrocephalus, A. purpureoniger, A. semotus, A. subperonatus, A. viridopurpurascens, and A. xanthoderma. Full descriptions are given for those taxa encountered by the authors in the field, including 10 species and considered cosmopolitan in distribution. Six of these species are new records for New Zealand.

Key to Agaricus species in New Zealand

Subgenus Agaricus

Basidiomata fleshy; general veil not woolly or detersile, usually poorly developed on pileus; pileus smooth or with fibrils or scales, sometimes cracked, epicutis without removable elements, margin not striped. Two groups may be separated

Basidiomata bruising reddish, rarely yellowing; general veil is usually well developed and forms a complex annulus with the partial veil; annulus may be formed mainly from the partial veil (often poorly developed); stipe usually cylindrical, solid, or hollow; Schäffer's cross-reaction negative; KOH test negative; odour fungal and never of anise or of almonds; basidiospores may have apical pore. Group 1

Basidiomata bruising yellowish; general veil poorly developed, usually reduced to flakes or strips on the lower surface of the annulus and the lower part of the stipe; partial veil usually well developed, forming a membranous annulus; stipe often bulbous and spindly, hollow, rarely solid; Schäffer's cross-reaction usually positive, may be negative; KOH test positive; usual to have odour of anise or of almonds, but may be unpleasant of phenolic, ink, turpentine, or carbolic acid; basidiospores without apical pore. Group 2

Key to Group 1

1. Lamellae edges fertile, lacking cheilocystidia, concolorous; basidiospores ellipsoid. 2
1. Lamellae edges sterile, lacking basidia, provided with well-developed cheilocystidia; annulus sturdy or fleshy, complex, formed by partial and general veil; basidiospores globose. 5
2. Pileus usually white, smooth or slightly scaly, spherical when young. Basidiospores with apical pore (may be rudimentary) 3
2. Pileus not white or with yellowing; basidiospores with no apical pore 4
3. Pileus 60-100 mm diam., becoming convex-applanate, surface silky smooth, bruising red; stipe cylindrical, narrowing at base. 1. A. campestris var. campestris.
3. Pileus 20-50 mm diam., becoming convex, often centrally depressed, surface scaly in centre, streaked towards the margin, white when young, latter yellowish. stipe pointed at the base, sometimes twisted, yellow below annulus, bruising yellow. 2.
A. campestris cf. var. floccipes.
4. Pileus dark purple-brown scales on lilac surface, scales decreasing towards the margin, bruising dark red; stipe woolly, with brown under the annulus. 3. A. porphyrocephalus Möll. (Fig. 2).
4. Pileus with dense light brown scales at centre, decreasing towards margin, brown to reddish on bruising; stipe smooth, brownish below annulus, surface floccose. 4.
A. cupreobrunneus (Möll.) Boh. (Fig. 2).
5. Flesh on cutting or bruising becoming intensively red or carmine red. Pileus scaly or fibrillose. 6
5. Flesh gradually becoming reddish-brown when cut or bruised, (this change may occur mainly in the stipe). 7
6. Stipe length usually less than pileal diameter. Pileus with scales, 50-250 mm diam., hemispherical when young, finally broadly convex-applanate, ± centrally depressed, surface with broad scales, sometimes becoming very pronounced during dehydration, whitish when young, finally brownish; colour change quickly to strong red when cut or bruised; odour unpleasant, of fish or algae. 5. A. bernardii.
6. Stipe length as much as double the pileal diameter; pileus 50-100 mm diam., fibrillose. Pileus thick, fibrillose; flesh changing colour when cut or bruised notably in the pileus and stipe apex areas; odour not of fish or algae. A. impudicus (Rea) Pil. (=variegans).
7. Basidia predominantly 2-spored, (rarely 1-, 3- or 4-spored). Usually developing above the soil or humus. Pileus 50-80 (120) mm diam., convex, brown scales on white surface; margin thick. 6. A. bisporus var. bisporus.
7. Basidia predominantly 4-spored. Often developing largely beneath the surface of the soil or humus. 8
8. Pileus (40-)90(-150) mm diam., very thick, fleshy, hemispherical when young, finally broadly convex to applanate, surface smooth to streaky, reddish brown to brown, with fibrillose scales. 7. A. subperonatus.
8. Pileus (30-)50(-70) mm diam., convex when young, finally broadly convex-applanate, surface silky to fibrillose, white when young, bruising ochraceous brown. 8. A. bitorquis.

Group 2

1. Odour anise or almonds; basidiomata yellowing to browning on pileus and stipe when bruised or exposed (not usually restricted to the base of the stipe), rarely reddening, general veil crumbly, often forming flakes at the base of the annulus. 2
1. Odour unpleasant, has been described as phenolic, ink, turpentine or carbolic acid; basidiomata often with intense yellowing when bruised at the base of the stipe and veil; may cause stomach upsets. 7
2. Mature basidiomata thick and fleshy, pileus may be wide, 50-300 mm diam.; Schäffer's cross-reaction positive or negative. 3
2. Mature basidiomata not thick and fleshy. Pileus small, 15-80 mm diam.; Schäffer's cross-reaction positive. 5
3. Pileus white, 40-120 mm diam.; Schäffer's cross-reaction positive. 9. A. arvensis.
3. Pileus not white, 60-250 mm diam.; Schäffer's reaction positive and/or negative. 4
4. Pileus 100-250 mm diam. globose, surface orange- brown, or dark orange, fibrillose, appressed, concentric scales; when broken or bruised usually becoming yellow, but may show pinkish-red towards the base of the stipe and above the annulus. Schäffer's cross-reaction positive. 11. A. augustus Fr.
4. Pileus 60-250 mm diam., fleshy, convex when young, then convex-applanate, sometimes with a depressed centre, moderate brown to dark brown scales on paler surface; reddening reaction when bruised or broken, but may show yellowing towards the base of the stipe; Schäffer's cross-reaction usually negative. 10. A. lanipes.
5. Pileus 15-40 mm diam., thin, convex when young, finally applanate, centre slightly umbonate, with fawn scales on white background at centre, decreasing towards margin; margin inrolled when young, finally straight, edge smooth, with remnants of veil; basidiospores 4-5 õ 2.5-3 ìm. 11. A. semotus.
5. Pileus 50-80 mm diam., not white or yellow, pileus surface dry or viscous; stipe club-shaped. 6
6. Pileus with flat-lying fibrillose scales, brown to reddish purple on a whitish background, surface dry; basidiospores 6.1-7.2 x 3.8-4.6 ìm, sometimes with thinning apex such that it looks like a pore. A. bambusae var. australis Heinem.
6. Pileus dark brown with olive glow; scaly on a clear background, covering viscous when in humid state; basidiospores 4.8-6.3 x 3.5-4.1 ìm, no apical pore.
A. viridopurpurascens Heinem.
7. Pileus greyish-ochraceous-brown or clay brown, in the centre with dark brown, appressed scales; bruising dull yellow, including towards the base of the stipe.
16. A. meleagris (J.Schff.) Imb.
7. Pileus white or grey-brown towards the centre, bruising yellow, glabrous, smooth, silky, may be covered with cracks or fissures, radially towards the margin; flesh bright-chrome-yellow towards the base of the stipe, especially with bruising. 17. A. xanthoderma Gen.

Subgenus Langagaricus

General veil usually woolly and/or detersile, well developed on the pileus, consisting of elongated and often multiseptate hyphae, sometimes scaly, (also on lower part of stipe), epicutis with removable elements.
1. Pileus and stipe base dark brown to chocolate brown, may have purple glow; Lamellae edges infertile; Schäffer's reaction negative. 2
1. Pileus red ochre; Schäffer's cross-reaction positive; Lamellae edges fertile with basidia. A. oligocystis Heinem
2. Basidiomata stocky; annulus fragile. A. horakii Heinem.
2. Basidiomata slender; annulus membranous. 3
3. Pileus and base of stipe dark brown; basidiospores 5.3-6 (6.5) x 3.4-3.7 ìm. A. lanatoniger Heinem.
3. Pileus and base of stipe dark brown with purple glow, scales velvet-like and flat lying; basidiospores 4.7-6.2 x (3) 3.2-3.7 ìm. A. purpureoniger Heinem.