Agaricus haematinus K.D. Hyde & R.L. Zhao
Index Fungorum number: IF551479 Facesoffungi number: FoF00986
Etymology: “heamatinus” means blood red, which refers to the blood red discolouring of the context on cutting.
Holotype: BBH 19516 Pileus 4–7 cm diam., and 5–6 mm thick, convex with inrolled margin, or concave with flared margin with age, cuticle exceeding, covered by floccose scales, snow white. Lamellae free, crowded, lamellulae with 2–3 series, 4.5– 6 mm broad, normal to slightly ventricose, dull red or reddish-brown, edge colour distinctly lighter than gills. Stipe 40–70×11–12 μm, cylindrical, taping to base, smooth above the annulus, floccose below the ring, but easy rubbed so appearing smooth in old fruiting bodies, white, small, hollow. Annulusfugacious, and often hanging along the pileus margin, middle or superior, torn. Context firm, white, no staining on touching, rubescence on cutting. Macrochemical reaction: KOH reaction negative. Basidiospores 5–7×4–5 μm [x = 5.9±0.4×4.6±0.4, Q=1.1–1.5, n=20], ovate with apiculus, broad ellipsoid, brown, reddish-brown, smooth. Basidia 17– 20×7–8 μm, clavate, smooth, hyaline, 4-spored. Cheilocystidia 16–21×9–14 μm, broadly clavate, pyriform, some with 1–2 septa at the base, hyaline, smooth. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 7.5–10 μm diam., elongate cylindrical arranged in parallel, smooth, hyaline. Annulus consisted by slender hyphae of 2.5–5 μm diam., loose interwoven, hyaline, smooth, branched.
Habitat and distribution: scattered on soil with excrements next to a chicken coop. Known only from Thailand.
Material examined: THAILAND, Chiang Mai Province, Mae Taeng District, Ban Pha Deng Village, N 19°17.123′ E 98°44. 009′, elev. 900 m, 19 September 2005, collector Ruilin Zhao, ZRL2136 (BBH 19516, holotype), (HMAS and SFSU, isotypes); Ibid., 2 August 2005, collector Ruilin Zhao, ZR2109 (BBH 19489, SFSU). The phylogenetic analysis shows that this new species forms a clade with the new species A. pseudolangei described above (see entry 141 of the present paper). As indicated in the notes on A. pseudolangei, further study will be necessary to know if this clade represent a new section or belong to a known section containing species exhibiting the red staining trait observed in these two species. This new species is diagnosed by its pure white basidiomata and strong blood red discolouration on cutting. In the field, it quite resembles A. campestris L. in having a pure white pileus, the taping base of stipe, and the character of annulus. However it differs in having larger spores (6.7–8× 4.6–5.3 μm, Kerrigan 1986; 6–8.5×4.6–6.7 μm, Parra 2008) and unchangeable context or which is slightly pink on exposure. Agaricus andrewii Freeman is another species having a pure white pileus and pinkish discoloration, however, it has larger spores (7.5–9.2×5.5–6 μm). Similarly A. benesii and A. sylvaticus can present the pure white caps sometimes, and septate cheilocystidia, but their lower side of annulus have cog-wheel scales.