Conobolbitina lignicola T. Bau & H. B. Song sp. nov.

Figs 2 A – D, 3 A, 3 B, 4, 5

Etymology.

“ lignicola ” refers to the species that inhabits decaying wood in forests.

Holotypus.

China • Jilin Province, Huadian City, Hongshi National Forest Park, 14 June 2025, 42°49'46"N, 127°07'48"E, alt. 454 m, T. Y. Zhang, ZTY 2561407 (FJAU 72922).

Diagnosis.

Conobolbitina lignicola is characterized by a subbulbous stipe base, subellipsoid to oblong basidiospores with an inconspicuous germ pore, and hyaline pileocystidia. It is further distinguished from Con. glutinosa by its occurrence in temperate broadleaf forests (vs. tropical rainforests of Oceania).

Description.

Basidiomata small-sized, pileus 1–2 cm in diameter, initially broadly conical to campanulate, later straight, subumbonate, and slightly plano-concave. The pileus center is mahogany brown (RAL 8016) to chocolate brown (RAL 8017), with the margin beige (RAL 1001), sand yellow (RAL 1002) to ochre yellow (RAL 1024). The pileus is hygrophanous, smooth, viscid, with distinct striations extending up to 1 / 2 of the center, the margin is even to slightly undulate. Context thin, sand yellow (RAL 1002) to ochre yellow (RAL 1024), with no specific odor or taste. Lamellae adnexed to narrowly adnate, ventricose, moderately crowded, unequal in length, light ivory (RAL 1015), sand yellow (RAL 1002) to ochre brown (RAL 8001), with serrulate edges. Stipe 1–3 cm long, 2–3 mm thick, cylindrical, ivory (RAL 1014) to sand yellow (RAL 1002), covered with a powdery pubescence and longitudinally striate. The base is slightly enlarged.

Basidiospores (60 / 3 / 3) (7 –) 7.5–10.3 (– 11) × (4.1 –) 4.3–5.6 (– 6) μm, Q = (1.52 –) 1.58–2 (– 2.44), Q m = 1.72 (± 0.15), nearly ellipsoid to oblong, lemon-shaped to amygdaliform in frontal view, with a slight suprahilar depression in side view, appear smooth to slightly rough under a light microscope, with pointed ornamentation visible under a scanning electron microscope, wall thick, containing oil droplets, germ pore diameter is less than 1 μm or inconspicuous. Basidiospores are ochre brown (RAL 8001) to clay brown (RAL 8003) in KOH solution. Basidia (16 –) 17–23 (– 24) × 7–10 (– 11) μm, clavate, 4 - spored, occasionally 2 - spored, sterigmata 3–5 μm long, basidia with vacuolar contents. Cheilocystidia (15 –) 19–41 (– 42) × 6–11 (– 12) μm, variable in shape, cylindrical and constricted at the center, broadly capitate, narrowly utriform, broadly clavate, subcylindrical, with slightly bifurcated apices, nearly femoral head-shaped, some with excrescences, and sterile margins. Pleurocystidia absent. Caulocystidia (15 –) 16–61 (– 65) × 6–14 μm, variable in shape, similar to cheilocystidia but slightly larger, spheropedunculate, utriform, subcapitate, subclavate, subcylindrical, femoral head-shaped, with swollen and bifurcated apices, some with excrescences. Pileipellis epithelioid hymeniderm, composed of (21 –) 23–42 (– 43) × (11 –) 12–24 (– 26) μm sphaeropedunculate or broadly clavate elements, with fawn brown (RAL 8007) pigment observed in the base when viewed in KOH solution. Pileocystidia (23 –) 24–54 (– 60) × 4–10 (– 12) μm, variable in shape, including capitate, narrowly utriform, clavate, subcylindrical, and capilliform forms. A gelatinous layer is present. All structures have clamp connections. A weakly positive reaction with ammonia solution is observed, resulting in the formation of rhomboid crystals.

Habitat.

It occurs singly or scattered on decaying wood in broad-leaved forests during summer.

Known distribution.

Jilin Province, China.

Additional specimens measured.

China • Jilin Province, Jilin City, Jiaohe City, Qianjin Forest Farm, 24 June 2021, 43°57'10"N, 127°42'7"E, alt. 650 m, Q. Q. Ye, Y 2408 (HMJAU 65106). China • Jilin Province, Huadian City, Hongshi National Forest Park, 31 July 2025, 42°50'02"N, 127°07'58"E, alt. 487 m, H. B. Song, S 2573110 (FJAU 72929).

Notes.

This species is distinguished from Con. glutinosa by its occurrence in temperate broadleaf forests (vs. tropical rainforests of Oceania), a grey-brown to deep date-brown pileus, a terete stipe, basidiospores with a distinct germ pore, and smooth cystidia (Horak and Hausknecht 2002). It differs from Con. viscosa by the latter’s olive-black pileus with an involute margin, stipe base with pale yellow mycelium, and indistinct veil (Watling 1975). It is distinguished from Con. sibirica by the latter’s non-subumbonate, olive-black pileus and its weakly to strongly pigmented pileocystidia with intracellular greyish-brown granular pigment (Crous et al. 2021). Furthermore, it differs from all members of the sect. Verrucisporae by its Bolbitius - like habit, lignicolous ecology, and distinct spore ornamentation. Phylogenetically, it forms a distinct clade sister to a cluster containing Con. sibirica and Con. fuscoviolacea, with strong nodal support, and can be readily distinguished.