Leucocoprinus atroferrugineus M. Ishaq, M. Fiaz & Khalid, 2025

Ishaq, Muhammad, Khan, Muhammad Binyamin, Lu, Wenhua, Asif, Muhammad, Tarafder, Entaj, Fiaz, Muhammad, Karunarathna, Samantha C., Khalid, Abdul Nasir & Wen, Ting Chi, 2025, Morphology and phylogeny reveal Leucocoprinus atroferrugineus (Agaricaceae), a new species from Pakistan, Phytotaxa 711 (2), pp. 117-130 : 125-129

Leucocoprinus atroferrugineus M. Ishaq, M. Fiaz & Khalid , sp. nov.

MycoBank No. MB852066; Figs. 2−3 .

Etymology: “ atroferrugineus ” refers to the reddish-brown pileus color.

Holotype: PAKISTAN, Khyber Pakhtunkhwa Province, Buner District, Pir Baba , 1021m a.s.l., under Pinus roxburghii Sarg in coniferous forest, 12 August 2018, Muhammad Ishaq, LAH36771 . GenBank accession ITS = OQ746332.

Diagnosis: Different from Leucocoprinus pyrrhulus due to dark reddish brown areolate-fibrillose squamules on the pileus, becoming dull reddish brown to reddish brown towards the margin, a hollow stipe with a pale pinkish apex, dark fibrils below the annulus, turning orange, then dark when scratched and presence of annulus, large (size) ellipsoid to amygdaliform basidiospores.

Description: Basidiomata medium-sized. Pileus 44−65 mm diam., ovoid initially, becoming plano-convex with puny umbo upon maturity, radially oriented tufts of fibrillose squamules, dark red-brown (5YR 3/2, 3/3, 3/4) at umbo, becoming dull red-brown (5YR 4/34,5/4) to red-brown (5YR 4/6,4/8) toward margin, areolate, on white background, with decurved margin, irregularly fringed, yellow to yellowish dark orange upon bruising. Lamellae white (2.5R 9/2) when young, becoming bright brown (2.5YR 5/6,5/8) to pink (2.7YR 6/8) at maturity, free, closed to crowded, ventricose. Stipe 35−75 × 3−5 mm, gradually widening toward base, 9 mm wide, whitish brown (10R 8/2) from above the middle, dull reddish brown (5YR 4/34, 5/4) fibrillose below the middle, white (2.5R 9/2) glossy tomentose base adhering to leaves or woody debris, solid. Annulus unclear, with a fugacious, partial veil present at a young age, disappearing when mature. Context up to 3 mm thick, white, and pliable. Smell fungoid. All parts of the basidiomata turn yellow-orange (7.5YR 7/8,8/8) on bruising or handling.

Basidiospores [60/3/1] (5.7 −) 7.3 − 8.2 (− 8.4) × (3.6 −) 3.63 − 4.4 (− 4.5) μm, L × W = 7.7 × 4.1μm, Q = (1.5 −) 1.7 − 2.1 (− 2.2), Qav = 1.9, oblong-ellipsoid, subcylindrical to amygdaliform, apiculate, hyaline, guttulate, smooth, thick - walled, dextrinoid. Basidia 15 − 17.7 × 6.7 − 8.3 μm, 4 - spored, clavate, thin-walled. Cheilocystidia 33−56 × 16−22 μm, broadly fusiform to narrowly utriform to utriform, thin-walled. Pleurocystidia absent. Pileipellis a cutis composed of hyphae 5.5 − 9.4 μm in diam, terminal elements 64 − 96 × 9.6 − 22 μm, reddish brown with obtuse ends having no pigments. Clamp connections absent in all tissues.

Macro-chemical reactions: Pileus, lamellae, and stipe turning bluish green with 5 % NH 4 OH.

Habitat: Saprotrophic, in small groups on the litter of Pinus roxburghii in coniferous forest with nutrient-rich loamy soil.

Additional materials examined: Pakistan, Khyber Pakhtunkhwa Province, Buner District, Gokand Valley Kot Village , 1650 m a.s.l., 15 August 2018, Muhammad Ishaq ( HUP11548 ), GenBank accession ITS = OQ746333 ; 25 July 2020 Muhammad Ishaq ( HUP11556 ), GenBank accession ITS = OQ746338 .

Discussion

Phylogenetic analysis, based on the ITS dataset, revealed that the three Pakistani sequences formed a well-supported monophyletic lineage, sister to Lc. pyrrhulus and Lc. flammeotinctoides Vellinga with 66% ML BS and PP = 0.90 support values ( Fig.1 ). Leucocoprinus atroferrugineus , is significantly different from Lc. pyrrhulus due to the presence of micro-morphological characteristics, such as its pileus plano-convex with a small umbo, dark-reddish brown at the umbo becoming dull-reddish brown to reddish brown toward the margin, and ellipsoid, sub-cylindrical to amygdaliform basidiospores. The pileus of Lc. atroferrugineus , measuring 44−65 mm diam, with dark reddish brown areolate-fibrillose squamules on the disc, becoming dull reddish brown toward the margin, is contrasted with Lc. pyrrhulus . Furthermore, the hollow stipe features a pale pinkish apex, dark fibrils below the annulus, which turn orange and then dark when scratched. The presence of an annulus adds to the significance of our findings ( Vellinga 2010). Another taxon, Lc. flammeotinctoides , initially has dark grey scales on the umbo, becoming dark brown to dark red-brown with white-cream to yellow-white lamellae. In contrast, Lc. atroferrugineus has areolate, dark-reddish brown radially oriented tufts of fibrillose squamules, at the umbo becoming dull reddish brown to reddish brown toward the margin with white, glossy lamellae. Furthermore, it has larger cheilocystidia (22–53 × 5–15 μm) and different shapes, as well as large-sized basidia (18–29 × 6.5–9.5 μm) ( Vellinga 2010).

Leucocoprinus dyscritus (Dovana, Angeli, Contu & Brandi) M. Asif , Saba & Vellinga reported from California, USA, is closely related to our new species; however, it can be differentiated by its convex to umbo piles with tuftyvelvety center, non-staining lamellae, amygdaliform basidiospores, cylindrical, fusiform, irregularly lageniform cheilocystidia, and pileus covering comprising squamules and tufts made up of short elements ( Vellinga 2010). Leucocoprinus erythrophaeus which has worldwide distribution is also an allied to our new species, however, differs due to its staining lamellae, the pseudocollarium to which the lamellae are attached, and in particular in the structure of the pileus covering that is composed of long often erect (trichodermal) elements, oblong and subamygdaliform basidiospores, and narrowly utriform, to irregularly cylindrical cheilocystidia ( Vellinga 2010).

Leucocoprinus birnbaumii (Corda) Singer is known for its vivid yellow basidiomata, convex to campanulate pileus, and striate margin. Although it shares the saprotrophic habitat and fragile texture, it differs markedly from Lc. atroferrugineus by its uniformly yellow coloration, lack of reddish-brown areolate squamules, and smaller, ovoid basidiospores ( Pegler 1983; Vellinga 2001). Leucocoprinus cepistipes (Sowerby) Pat. also grows on rich organic material and has white basidiomata with a scaly disc. However, it lacks the dark reddish-brown areolate-fibrillose pileus surface and orange to dark color change upon bruising found in Lc. atroferrugineus . It also differs in spore size and shape (larger and more amygdaliform in our species) ( Vellinga 2001; Bon 1987). Leucocoprinus brebissonii (Gilbert & Kühner) Bon is reported to have a whitish, scaly pileus and a pale stipe, but it lacks the intense reddish-brown coloration and bruising reaction characteristic of this species. It has smaller spores and distinct cheilocystidia ( Bon 1987; Vellinga 2004). Leucocoprinus ianthinus (Bull.) Locq. is known for purplish to violet tinges on the pileus and pileus surface, composed of trichodermal hyphae. In contrast, our species lacks violet pigmentation and shows unique areolate, reddish-brown squamules and an orange-staining context, which are not reported in Lc. ianthinus ( Vellinga 2001, 2004).

Hence, from all the discussion and comparisons with the closely allied species, it is concluded that our proposed new species, i.e., Lc. atroferrugineus has unique morpho-anatomical characteristics, along with a DNA profile, that distinguish it from all previously known species of this genus.

Figures

FIGURE 1. Phylogenetic tree of Leucocoprinus atroferrugineus based on Maximum-likelihood analysis of ITS region. Maximum likelihood (ML) equal to or higher than 70% and Bayesian probability (BYPP) equal to or higher than 0.7 are shown for each node above the branch leading to that node. The newly described species is indicated in bold and different color.

FIGURE 2. Morphology of Leucocoprinus atroferrugineus, including images of all three collections. A–B. Surface of pileus C–D. View of the lamellae from young stage to maturity E. View of pileus and stipe F. Lamellae turning green when reacting with 10% NH OH. Scale 4 bars:A−F = 10 mm.

FIGURE 3. Anatomical feature of Leucocoprinus atroferrugineus. A. Basidiospores, B. Basidia, C. Cheilocystidia, D. Pileipellis. Scale bars A = 3 μm, B = 5 μm, C = 5 μm, D = 3 μm.