Leucoagaricus glareicolor Ashraf, S., Naseer, A. & Khalid, A.N., 2023

Ashraf, Shazia, Naseer, Arooj, Usman, Muhammad & Khalid, Abdul Nasir, 2023, Two new species of genus Leucoagaricus (Agaricaceae, Agaricales) from Pakistan, MycoKeys 96, pp. 159-171 : 159

Leucoagaricus glareicolor Ashraf, S., Naseer, A. & Khalid, A.N. sp. nov.

Figs 3 , 4 , 5

Etymology.

The specific epithet glareicolor (Latin) refer to the brownish black color of umbo and fibrils on pileus.

Diagnosis.

Is distinguished due to brown to blackish brown, broadly umbonate, white pileus with blackish brown fibrillose to rugulose, smooth sub-bulbous stipe with annulus in upper 1/3 of stipe, smaller (5.65-7.70 × 3.44-5.63 µm) basidiospores and cheilocystidia without crystals at apex.

Holotype.

Pakistan, Islamabad, Margalla Hills National Park, Trail 5, 33°45'01.1"N, 73°05'14.5"E, 1303 m a.s.l., August 28, 2018, Shazia Ashraf & Arooj Naseer MH-169 (LAH37456) GenBank: OP605605 (ITS) and OP782028 (LSU)

Description.

Basidiomata medium to large-sized, soft shiny, fragile solitary. Pileus 4-4.2 cm, plano-convex to plane at maturity, radially fibrillose to rugulose towards margins, broadly umbonate, umbo brown when young, becoming blackish brown with age, disc creamy white (1.7GY 6.4/1.6) with dark brown (3.8Y 3.5/3.2) to blackish brown (4.8Y 5.5/8.2) rugulose towards margins, shiny and sericeous, on maturity broadly striated and overextended blackish brown fibrils darker in center and lighter towards margin, margin incurved and appendiculate. Lamellae free to approximate, adnexed, distant, fragile, edges entire, yellowish creamy (1.7GY 6.4/1.6) to grayish brown (4.8Y 5.5/8.2). Lamellulae irregular, alternating with lamella, in 2-3 tiers. Stipe 6.2-6.7 cm in length, tapering upwards, 0.5 cm at apex, 1.7 cm at base, sub bulbous, yellowish creamy (1.7GY 6.4/1.6) central, cylindrical, smooth, shiny. Annulus present, superior, thin, made up of cottony scales, non-persistent in nature. Flavor and odor not distinctive. Basidiospores [60/3/2] (5.65-) 5.66 - 7.73 (-7.76) × (3.43-) 4.11 - 4.6 (-5.63) µm, 5.65-7.70 × 3.44-5.63 µm, Q = 1.23-1.70, Qav = 1.48, hyaline in 5% KOH, oval at face view, lacrymoid to amygdaliform in side-view, guttulate, smooth, dextrinoid, thin-walled and apiculate. Basidia (12.06-) 13.08 - 23.5 (-24.03) × (6.86-) 7.7 - 8.72 (-9.72) µm, 12.9-18.5 × 5.8-7.7 µm, narrowly clavate, hyaline in 5% KOH, smooth, with 2-4 prominent sterigmata, oil droplets present, no clamp at base. Cheilocystidia (15.12-) 16.12 - 24.9 (-25.98) × (6.88-) 7.8 - 8.4 (-9.43) µm, 15-26 × 6.8-9.4 µm, hyaline in 5% KOH, thin-walled, clavate to narrowly clavate, smooth, without internal content and clamp. Pleurocystidia absent. Many layers of isodiametric irregular epithelial cells av = 7.87 µm in diameter, at the base of basidia and cystidia. Pileipellis trichoderm, made up of septate, cylindrical hyphae 5.6-7.7µm in diam., thin-walled, light brown to reddish pigment in the center, light orange to yellowish pigment towards margin in 2% KOH, clamp connections absent. Stipitipellis cutis compactly arranged, made up of septate, cylindrical hyphae 3.4-7.1µm in diam., av. w = 5.86 µm thin-walled, hyaline in 2% KOH, clamp connections absent.

Additional material examined.

Pakistan, Islamabad , Margalla Hills National park, Trail 5, 33°45'01.1"N, 73°05'14.5"E, 1303 m.a.s.l., July 27, 2018 Shazia Ashraf & Arooj Naseer, MH-65 ( LAH37555 ), GenBank for ITS OP605604 & OP782029 for LSU ).

Comments.

Leucoagaricus glareicolor is characterized by broad umbo that is brown to blackish brown, fibrillose to rugulose white pileus. The stipe is smooth, sub-bulbous with annulus that is present in upper 1/3 of stipe. Anatomically, Leucoagaricus glareicolor has smaller (5.65-7.70 × 3.44-5.63 µm) basidiospores and cheilocystidia without crystals at apex.

Leucoagaricus glareicolor shows close relationship with L. subvolvatus and L. menieri . Leucoagaricus subvolvatus and L. glareicolor share many similarities like same pileus color, size and shape. However, L. subvolvatus has broad yellow umbo with yellow, fine fibrils while L. glareicolor has very prominent, blackish brown umbo with blackish brown fibrils. Leucoagaricus subvolvatus is characterized by stipe base with a marginal bulb. Leucoagaricus glareicolor has slightly bulbous stipe. Furthermore, Leucoagaricus subvolvatus has annulus at lower part of stipe while Leucoagaricus glareicolor has prominent annulus in upper 1/3 half of stipe. Furthermore, Leucoagaricus subvolvatus has cheilocystidia with crystals at apex whereas Leucoagaricus glareicolor cheilocystidia lacks crystals at apex ( Candusso and Lanzoni 1990).

Compared to Leucoagaricus menieri , characterized by light yellow, slightly umbonate pileus which is milky white while Leucoagaricus glareicolor has brownish black umbo, creamy white pileus with blackish brown fibrils. The stipe in the former is more bulbous (4-5 mm) as compared to subbulbous (0.5-1.7 cm) stipe in Leucoagaricus glareicolor . Anatomically Leucoagaricus menieri is differentiated from Leucoagaricus glareicolor by longer basidiospores {(6.9-)7.4(-8.7)} and the presence of crystals at apex of cheilocystidia. Another closely related taxon is Leucoagaricus sardous that is differentiated by our taxa by broader {5-6.8 (7.3)} basidiospores and larger (upto 75 µm) cheilocystidia. The next closely related taxon is L. volvatus that is characterized by the gelatinized, white pileus with olivaceous tinges and presence of crystals on cheilocystidia.

Molecular phylogenetic analyses based on ITS and LSU sequences also support La. glareicolor as a distinct species with strong bootstrap support.

Figures

Figure 3. Morphological description of Leucoagaricus spp. from Pakistan A, C Leucoagaricus margallensis B, D Leucoagaricus glareicolor.

Figure 4. Anatomical features of Leucoagaricus margallensis A basidia B basidiospores C cheilocystidia D pileipellis E stipitipellis. Scale bars: 10 µm (A); 5 µm (B-E).

Figure 5. Anatomical features of L. glareicolor A basidia B basidiospores C cheilocystidia D pileipellis E stipitipellis. Scale bars: 5 µm (A-C); 10 µm (D, E).