Public Description of Leucoagaricus caerulescens (Peck) J.F. Liang, Zhu L. Yang & J. Xu

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Name: Leucoagaricus caerulescens (Peck) J.F. Liang, Zhu L. Yang & J. Xu
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Description status: Unreviewed

General Description:

Leucoagaricus caerulescens is characterized by white context, clavate to broadly clavate cheilocystidia and the bluish green change of basidiomata when dried (Peck 1899, Morgan 1906), but the blue tint did not persist in herbarium collections.
Leucoagaricus caerulescens originally was described as L. coerulescens [sic] by Peck (1899). Morgan (1906) considered L. erythrella e. (subsp.) virescens Speg. with L. coerulescens [sic] as conspecific and used the name L. virescens (Speg.) Morgan for the species. Based on the type specimen of L. coerulescens and literature reviews of L. virescens, we consider the two specimens as conspecific. L. caerulescens (1899) should have priority over L. virescens (1906), according to nomenclatural priority (Mcneill et al. 2006). In addition we propose to transfer the species from the genus Lepiota to Leucoagaricus based on the morphological features.

Diagnostic Description:

Pileus 1.5-2.0 cm diam, convex, obtuse to slightly umbonate, center brownish, elsewhere with whitish ground, and covered with brownish squamules. Context thin, whitish. Lamellae free, white, crowded; lamellulae present. Stipe 3.0-5.0 cm x 2-3 mm, subclavate, hollow, glabrous, brownish.

Basidiospores (fig. 4A) [20/1/1] (7.0-)7.5-9.5 (-10.0) x 4.0-5.0 µm (Q = 1.56-2.00, Q = 1.84 ± 0.13), amygdaliform in side view, attenuate toward apex, ovoid in front view, without germ pore, hyaline, smooth, slightly thick-walled, dextrinoid, congophilic, metachromatic in cresyl blue. Basidia 16-22 × 7-12 µm, clavate, four-spored, hyaline. Cheilocystidia (fig. 4B) 21.5-39 × 10-20 µm, clavate to broadly clavate, rarely narrowed at the apex, thin-walled, hyaline. Pleurocystidia absent. Pileipellis (fig. 4C) a loosely arranged cutis of cylindrical hyphae; terminal elements suberect, sometimes differentiated, 24-51 (-61) x 6-11 µm, subcylindrical to narrowly clavate, thin-walled, with pale brown intracellular pigments, and often encrusted with brown pigments at base. Clamp connections absent.

Materials examined: USA: Ohio. C.G. Lloyd (NYS, holotype).

Distribution. - Eastern North America.


Description author: Excited delirium [EXD]▼ (Request Authorship Credit)
Description editor: Joseph D. Cohen