Chlorophyllum palaeotropicum Z.W. Ge & A. Jacobs

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 : 72-73

Chlorophyllum palaeotropicum Z.W. Ge & A. Jacobs sp. nov. Figs 3D, 5

Diagnosis.

This species is distinguished from other Chlorophyllum species by medium-sized basidiocarps with distinct brownish squamules composed of a trichodermal layer of subcylindrical brownish hyphae and slightly enlarged terminal elements, the greenish subglobose basidiospores without a germ pore and the clavate to narrowly clavate cheilocystidia with brownish to fuscous brown vacuolar pigments.

Type.

SOUTH AFRICA. 2229 BD Kamkusi, Farm Ludwigslust 163MS (− 22°15.39'S, 29°47.48'E), alt. 582 m, near open area along dirt road, growing in loam soil, compost-rich - mopane ( Colophospermum mopane) leaf layer, 30 November 2013, Van Der Walt, R 715 (Holotype: PREM 62142!; isotype: HKAS!). ITS barcoding sequence: MG741978.

Description.

Pileus 50-100 mm broad, hemispherical to convex at first, expanding to convex to broadly convex with age; surface covered with fibrillose, tufted, reddish-white (7A2) to brownish-orange (6C3) squamules at the margin and brownish-grey (6C2), orange grey (6B2), to greyish-brown (7D3) plate-like squamules at the centre. Lamellae free and remote from stipe; white to off-white when young, whitish to greenish-white (26A2) when mature, crowded, 6-11 mm deep, with 1-2 series of lamellulae. Stipe 16-90 × 3.5-8 mm, subcylindrical, with slightly enlarged base, straight or curved, white; hollow, nearly stuffed, with an annulus at the middle part of the stipe. Context white, 4-6 mm thick in pileus, white in pileus and stipe, discolouring pastel pink (7A4) when drying, with a distinct mushroom smell, taste mild. Spore print greyish-green (30B3-30B4).

Basidiospores [100,5,3] (8.0)8.5-11.0(12.0) × (6.0)7.0-9.0(10.0) μm (mean 9.8 ± 0.9 × 8.0 ± 0.8 μm), Q = 1.0-1.4, Qav = 1.2 ± 0.05, ellipsoid, oblong in side view or in frontal view, with rounded apex, smooth, hyaline when young, greenish-white (27A2), olive to brownish (in KOH) when mature, congophilous, dextrinoid, without germ pore, slightly thick-walled; mature basidiospores staining purplish-red (14A6-14A7) in cresyl blue; immature basidiospores staining bluish-violet (18B7) in cresyl blue. Basidia 29-33 × 10.0-12.0(15.0) µm, clavate, hyaline, 4-spored. Cheilocystidia (13)20-55(63) × 10.0-15.0(20.0) µm, clavate, rarely broadly clavate or narrowly clavate, brownish to fuscous brown, sometimes septate. Pleurocystidia absent. Lamella trama slightly interwoven, made up of subcylindrical hyaline hyphae, 8-14 μm diam. Pileipellis a trichoderm made up of filamentous or cylindrical hyphae, slightly inter woven, interspersed with brown to tea brown hyphae, 8-14 µm in diam., thick-walled, with brownish vacuolar pigments; wall brownish-yellow; terminal elements mostly slightly enlarged to narrowly clavate, rarely cylindrical. Clamp connections present on basal septa of young basidia and tissue of annulus, but not common.

Distribution.

Known from Benin and South Africa in Africa and from China in Asia.

Ecology.

Saprotrophic, solitary to scattered, terrestrial.

Etymology.

(L.) with reference to distribution of this species in the Old World tropics.

Additional specimens examined.

BENIN. Okpara: countryside of North-eastern Parakou, 15 km from Parakou, alt. ca 330 m, 18 June, 2015, G. Wu 1370 (HKAS 93747). CHINA. Hainan Province: Sanya, Yalongwan, on man-made lawn near seaside, 29 June 2010, Z.W. Ge 2519 (HKAS 60195). SOUTH AFRICA. 2229 BB Beit Bridge, Farm Wimpsh 139 MS, 12 February 2014, Van Der Walt, R891 (PREM 62144), growing in cleared area, near water hole, among Bulbostylis hispidula ; 2229 BD Kamkusi, Farm Ludwigslust 163 MS (farm yard), − 22°16.64'S, 29°48.22'E, alt. 606 m, growing in loam soil in cleared area, in semi-shade to full sun, 9 March 2014, Van Der Walt, R 938 (PREM 62145); 2229 BD Kamkusi, Farm Ludwigslust 163MS (− 22°16.64'S, 29°48.22'E), alt. ca. 610 m, growing in loam soil in cleared area, 14 February 2014, Van Der Walt, R 905 (PREM 62146).

Discussion.

Chlorophyllum palaeotropicum is very similar morphologically to C. shimogaense Sathe & S.M. Kulk. Both species have medium-sized, hemispherical to convex pilei covered with reddish-white to brownish-orange squamules composed of a trichodermal layer. Both species also possess clavate cheilocystidia and subglobose basidiospores. However, C. shimogaense possesses an umbonate pileus, basidiospores with an indistinct or absent germ pore, much smaller basidia (13-24 × 6-8.5 μm) and no clamp connections ( Sathe et al. 1981 ( ‘1980’)).

Chlorophyllum palaeotropicum is also similar to C. molybdites , C. globosum and C. pseudoglobosum in general appearance due to the brownish to reddish discolourations where bruised, but C. palaeotropicum differs from these three species in having subglobose to globose basidiospores without a germ pore (apex rounded), while C. molybdites , C. globosum and C. pseudoglobosum have amygdaliform basidiospores with large germ pores (apex truncate).

Chlorophyllum palaeotropicum also resembles C. sphaerosporum on account of the basidiocarps bearing similar subglobose basidiospores without a germ pore. However, the squamules of C. sphaerosporum are made up of a hymenidermal layer composed of clavate to broadly clavate terminal elements. Furthermore, the context of C. sphaerosporum does not change colour when bruised. So far, C. sphaerosporum has only been recorded from temperate regions in northern China. These two species also belong to two different sections (Figure 1).

Chlorophyllum palaeotropicum is somewhat similar to L. zeyheri on account of the overall appearance, the broadly ellipsoid basidiospores and clavate cheilocystidia. However, L. zeyheri has much larger basidiocarps measuring 10-22 cm or larger and pale pink spore prints ( Pearson 1950). Furthermore, L. zeyheri has larger basidiospores (15.0-17.0 × 10.0-12.0 µm) with a germ pore ( Pearson 1950).