Hygrophorus alboflavescens A. Naseer & A.N. Khalid

Naseer, Arooj, Khalid, Abdul Nasir, Healy, Rosanne & Smith, Matthew E., 2019, Two new species of Hygrophorus from temperate Himalayan Oak forests of Pakistan, MycoKeys 56, pp. 33-47 : 36-37

Hygrophorus alboflavescens A. Naseer & A.N. Khalid sp. nov. Figures 1, 2

Diagnosis.

Hygrophorus alboflavescens can be distinguished from related species by its white, centrally depressed pileus having yellow dots, with straight, even margins; occurrence of white stipe with yellow patches at lower half and broader (4.98 μm) basidiospores.

Typification.

PAKISTAN. Khyber Pakhtunkhwa Province, Swat, Shawar Valley, 2100 m alt., solitary or in pairs, on soil under Quercus incana , 14 July 2014, Arooj Naseer & Abdul Nasir Khalid, ASSW36 (holotype: LAH35243).

Etymology.

The species epithet refers to the white pileus with yellow dots and white stipe with yellow patches.

Basidiomata medium to large sized. Pileus 7-10.5 cm in diameter, butter white (0.1B 8.8/0.3) with yellow (5.2Y 4.3/4) dots, plane, centrally depressed, context moderately thick, margin, even, smooth, straight, sometime incurved. Lamellae white (5.1GY 7.9/1.9) with yellow (6.1 Y 6.8/5.5) and pink (2.8Y 6.9/3.9) colouration, decurrent, thick, distant, L = 30-41, even, entire. Lamellulae irregular, of variable length, alternating with lamellae. Stipe 1.5-2.5 cm thick at apex, 0.5-1.5 cm at base, 8 -12.5 cm long, white (0.1B 8.8/0.3) with yellow (5.4Y 5.3/4) patches at lower half, cylindrical, slightly tapering at base, central, hollow.

Basidiospores [60/3/2] (5.52-) 5.6-7.9 (-8.1) × (3.84-) 3.9-6.5 (-6.7), avL × avW = 6.64 × 4.98, Q = (1.20-) 1.21 × 1.40 (-1.43), avQ = 1.34, light green to hyaline in 5% KOH, ellipsoid, oblong, thick-walled. Basidia 31.6-48.8 × 5.8-6.7 μm, hyaline in 5% KOH, four-spored, clavate with long sterigmata (up to 3.0-4.2 μm), densely guttulated. Hymenophoral Trama 4-5.2 μm in diameter, thin-walled, branched, septate, oil contents, clamp connection present. Pileipellis an ixocutis of wide, thick hyphae, 3.0-5.5 μm in diameter. Stipitipellis a cutis of parallel and erect hyphae, 3.1-5.3 μm in diameter, light yellow in 5% KOH, septate. Clamp Connections present in all tissues.

Habit and distribution.

Solitary and in pairs on soil under Quercus incana , at 2100 m a.s.l., in thick moist temperate forest of the western Himalaya.

Additional material examined.

PAKISTAN, Khyber Pakhtunkhwa province, Swat, Shawar Valley, 2100 m a.s.l., solitary or in a pair, on soil under Quercus incana , 14 July 2014, Arooj Naseer & Abdul Nasir Khalid, ASSW81 (LAH35244; FLAS-F-59457).

Notes.

Hygrophorus alboflavescens nom. prov. can be distinguished from closely related species by the following combination of characters: a white, plane, centrally depressed pileus having straight margins; stipe that is white above and yellow below; and broadly ellipsoid spores. The closely related species Hygrophorus penarioides is also an oak-specific species (Table 1). However, they differ morphologically. Hygrophorus penarioides can easily be distinguished by its convex pileus with broad umbo and its involute margins ( Jacobsson and Larsson 2007), whereas H. alboflavescens has centrally depressed pileus (without umbo) and straight margins. Hygrophorus penarioides has a pure white pileus and stipe which become cream or slightly pinkish with age, whereas H. alboflavescens has a white stipe and pileus with yellow colouration on both. Hygrophorus alboflavescens has a longer stipe (8-12.5 cm) and broader spores (3.9-6.7 μm) as compared to H. penarioides . Hygrophorus alboflavescens is further differentiated from closely related taxa, H. sordidus , which has a convex, expanded to plane pileus that is larger (8-20 cm broad) compared with the smaller (7-10.5 cm broad), centrally depressed pileus of H. alboflavescens . Hygrophorus alboflavescens has even, smooth and straight margins that differ from involute and subnoccose margins of H. sordidus . Molecular analyses based on ITS and LSU regions also support H. alboflavescens as a distinct taxon and demonstrate its ECM relationship with oak in Pakistan.