Chlorophyllum africanum Z.W. Ge & A. Jacobs, sp. nov.

Ge, Zai-Wei, Jacobs, Adriaana, Vellinga, Else C., Sysouphanthong, Phongeun, Walt, Retha van der, Lavorato, Carmine, An, Yi-Feng & Yang, Zhu L., 2018, A multi-gene phylogeny of Chlorophyllum (Agaricaceae, Basidiomycota): new species, new combination and infrageneric classification, MycoKeys 32, pp. 65-90 : 70-71

Chlorophyllum africanum Z.W. Ge & A. Jacobs, sp. nov. Figs 3A, 4

Diagnosis.

This species is distinguished from other Chlorophyllum species by relatively small basidiocarps with yellow grey to grey orange (5B4) furfuraceous squamules, the squamules composed of a hymenidermal layer made up of greyish-yellow to dull yellow, narrowly clavate to clavate elements, the hyaline ellipsoid basidiospores without a germ pore and the hyaline, cylindric to slightly fusiform cheilocystidia.

Type.

SOUTH AFRICA. 2229 BB Beit Bridge, Farm Matolege 133 MS (− 22°14.91'S, 29°47.29'E), alt. ca. 560 m, growing in disturbed area with large volume of animal droppings, 9 February 2014, Van Der Walt, R 885 (holotype: PREM 62143!; isotype: HKAS!). ITS barcoding sequence: MG741962.

Description.

Pileus 30-50 mm broad, hemispherical to convex when young, expanding to broadly convex or applanate with age, sometimes with a prominent umbo; margin sulcate striate; surface covered with thin, yellow grey (4B2-4B3), orange grey (6B2) to grey orange (5B4) furfuraceous squamules, these remaining intact on the disc but elsewhere diffracted-scaly with expansion and receding from pileus margin. Lamellae free and remote from stipe, white to off white, crowded, narrow, up to 6 mm deep, with 1-2 series of lamellulae; edges entire, white. Stipe 35-60 × 3-6 mm, subcylindric, slightly enlarged at base, glabrous, white to light brown, hollow, nearly stuffed, with a simple annulus about 10-15 mm from top of the stipe. Context white, 1-2 mm thick in pileus, discolouring brown to red where bruised or handled, with strong mushroom odour, taste mild. Spore print white to cream.

Basidiospores [100,5,2] (7.5)8.0-9.0 × (5.5) 6.0-6.5(7.0) μm (mean 8.2 ± 0.4 × 6.2 ± 0.3 μm), Q = (1.2)1.3-1.4 (1.5), Qav = 1.3 ± 0.05, ellipsoid, occasionally ovoid in side view or in frontal view, with rounded apex, smooth, hyaline, congophilous, dextrinoid, with one guttule in most cases, without germ pore, slightly thick walled, becoming purplish-red (14A6-14A7) in cresyl blue. Basidia 29-33 × 10.0-11.0 µm, clavate, hyaline, 4-spored, rarely 2-spored. Cheilocystidia 28-50 × 6.0-10.0 µm, cylindric to slightly fusiform, hyaline. Pleurocystidia not observed. Lamella trama regular to slightly interwoven, made up of subcylindrical hyaline hyphae, 7.0-12.0 μm diam. Pileipellis a hymenidermal layer made up of greyish-yellow (1B4, 2B3) to dull yellow (3B3), clavate elements of 21-50 × 9.0-14.0(16.0) µm, slightly thick walled, with greyish-yellow vacuolar pigments; wall greyish-yellow; terminal elements mostly narrowly clavate. Clamp connections not observed.

Distribution.

So far, only known from South Africa.

Ecology.

Saprotrophic, solitary to scattered, terrestrial.

Etymologyл

(L.) in reference to Africa where it is collected.

Additional specimens examined.

SOUTH AFRICA. 2229 BB Beit Bridge, Farm Matolege 133MS, − 22°14.66'S, 29°46.75'E, 574 m, on soil. 10 January 2014, Van Der Walt, R787 (PREM 62140). 2229 BD Kamkusi, Farm Ludwigslust 163 MS (Farm Yard), − 22°16.64'S, 29°48.22'E, alt. ca. 610 m, 9 March 2014, Van Der Walt, R935 (PREM 62141). Scattered in sandy soil of semi-shade to full sun, cleared area.

Discussion.

Chlorophyllum africanum is morphologically very similar to C. bharatense Sathe & S.M. Kulk. Both species have a small-sized convex to applanate pileus covered with pale olivaceous brown squamules, clavate cheilocystidia and broadly ellipsoid basidiospores. However, C. bharatense differs from C. africanum by the umbonate pileus, lamellae that become reddish- brown on drying, basidiospores with an indistinct or absent germpore and squamules composed of a trichodermal layer ( Sathe et al. 1981 ( ‘1980’)).

Chlorophyllum africanum is also similar to C. hortense on account of the small-sized basidiocarps, ellipsoid basidiospores and subcylindrical cheilocystidia. However, C. hortense differs from C. africanum by 2-spored basidia and the whitish context of the stipe becoming reddish where bruised ( Akers and Sundberg 1997; Vellinga 2003b).

Chlorophyllum demangei (see below) is characterised by the frequent and obviously umbonate pileus and large basidiospores measuring (7.5) 8.0-10.5 (12.5) × (5.0) 5.5-7.0 (7.5) µm. Molecular phylogenetic results clearly support the recognition of the two as separate species.

Leucocoprinus zeylanicus (Berk.) Boedijn, described from Sri Lanka, is also similar to C. africanum due to the small-sized pileus with a distinct umbo, the subcylindric cheilocystidia and the short ellipsoid basidiospores ( Pegler 1986). However, the finely radially silky-striate pileus of Lc. zeylanicus beset with sparse, minute, blackish-brown repent squamules and the basidiospores with a small germ pore ( Pegler 1986), differentiate this species from C. africanum .

Lepiota zeyheri (Berk.) Sacc., a species also found in South Africa, is somewhat similar to C. africanum on account of the whitish pileus with a clay brown umbo that is elsewhere covered with cream or brown squamules and the ellipsoid basidiospores. However, L. zeyheri has much larger basidiocarps measuring 10-22 cm or larger, a pale pink spore deposit, larger broadly ellipsoid basidiospores (15.0-17.0 × 10.0-12.0 µm) with a germ pore and clavate cheilocystidia ( Pearson 1950).