Hymenagaricus Heinem.

Yang, Kun L., Lin, Jia Y., Li, Guang-Mei, Liu, Zhen-Chao, Hosen, Md. Iqbal & Yang, Zhu L., 2024, Heinemannomyces, Hymenagaricus and Xanthagaricus revisited (Basidiomycota, Agaricaceae), Phytotaxa 659 (2), pp. 112-164 : 124-125

Hymenagaricus Heinem. , Bulletin du Jardin Botanique National de Belgique / Bulletin van de Nationale Plantentuin van België 51(3/4): 465–466 (1981)

= Heinemannomyces Watling, Belgian Journal of Botany 131(2): 133 (1999)

Type species:— Hymenagaricus hymenopileus (Heinem.) Heinem. , Bulletin du Jardin Botanique National de Belgique / Bulletin van de Nationale Plantentuin van België 51(3/4): 466 (1981)

Diagnostic characteristics:— Basidiomata usually small to medium-sized. Pileus usually less than 65 mm in diameter when mature, convex, plano-convex to plano-concave; background usually whitish to palely brownish; squamules usually more or less flaky at center, becoming granular, furfurous, woolly to fibrous towards margin, usually brownish, becoming lighter towards margin; margin usually appendiculate, not or indistinctly striate; context usually whitish, without a color change or turning reddish after damaged. Lamellae usually free, darkly brownish when mature, crowded, with a slightly serrate edge; lamellulae abundant. Stipe usually more than 1.2 times longer than the diameter of the pileus, subcylindrical, slightly curved and tapering downwards; background usually whitish to palely brownish; squamules usually granular, furfurous to fibrous, usually more abundant below the annulus, usually whitish; context usually whitish, without a color change or turning reddish after damaged. Annulus usually superior, easily broken and fugacious. Odor usually fungal. Taste usually fungal.

Basidiospores usually ellipsoid, slightly thick-walled, seeming usually smooth, tinged brownish, rarely bluish to purplish, without or with an indistinct germ pore, without endosporal thickening. Basidia usually clavate, 4-spored. Lamella trama usually regular to subregular. Cheilocystidia usually moderately abundant to abundant, clavate to subcylindrical in outline, thin-walled, smooth. Pleurocystidia usually absent. Pileus squamules usually hymeniform at center, becoming subhymeniform, epithelioid to trichoid towards the margin. Stipe squamules usually trichoid. Clamp connections usually absent in all tissues.

Habitat and distribution:— Solitary, gregarious, or strongly caespitose, scattered on soil as individuals or clusters, in forests. Currently, it is mainly known from paleotropical regions ( Burundi, China, Malaysia, Oman, Pakistan, Sri Lanka, South Africa, Thailand, and Togo).

Additional notes: This genus is similar to Xanthagaricus , but the latter usually presents yellowish or violetish squamules on pileus, whitish to brownish lamellae when mature, yellowish or bluish-tinged basidiospores and epithelioid to subhymeniform elements in pileus squamules, differing from the usually brownish squamules on pileus, darkly brownish lamellae when mature, brownish tinged basidiospores and hymeniform elements in squamules at pileus center of the former. Hymenagaricus also usually presents slightly larger and more robust basidiomata, and flakier squamules at pileus center than those of Xanthagaricus . Notably, it is unclear whether this genus presents diverse basidiospore ornamentation like that of Xanthagaricus , because only the basidiospores of a few species in this genus have been examined under SEM ( Heinemann & Little Flower 1984).