Collybiopsis dentata J. Q. Yan, L. Ding, & S. N. Wang, 2025

Ding, Ling, Zhong, Ben-Jian, Zeng, Hui, Wang, Sheng-Nan & Yan, Jun-Qing, 2025, Four new species of Collybiopsis (Omphalotaceae, Agaricales) from subtropical regions of China, MycoKeys 118, pp. 289-311 : 289-311

Collybiopsis dentata J. Q. Yan, L. Ding, & S. N. Wang sp. nov.

Fig. 4

Etymology.

Refer to the Latin “ dens, ” meaning “ tooth ” — the lamellae edges are dentate.

Holotype.

China • Zhejiang Province: Lishui City, Qingtian County, Shigu Lake , 31 July 2021, Jun-Qing Yan, Bin-Rong Ke, Zhi-Heng Zeng, HFJAU 2586 .

Diagnosis.

This species is characterized by white lamellae that are free, basidiospores 3.9–4.7 µm broad, fusiform to utriform pleurocystidia, and cheilocystidia measuring up to 30–71 × 17–29 µm.

Macrostructures.

Pileus 3.0– 8.5 mm in diam., convex to plane, umbilicate, margin entire, sulcate towards margin, white, light brown (7 D 5–6) at the center. Lamellae free, distant, with 1– 2 types of lamellulae, white, edges serrate, concolorous with the lamellae. Stipe 2.0–4.0 × 0.4–1.0 mm, central, hollow, cylindrical, equal, darkening towards the base, white at the apex to reddish-brown (8 E 5–6) at the base, surface covered with white pruinose, no white mycelium observed at the base.

Microstructures.

Basidiospores in side view [n = 44] (6.3) 6.7–8.2 (8.6) × (3.8) 3.9–4.7 (5.0) µm (av = 7.5 × 4.3 µm, Q = 1.6–2.0 (2.1) (Qm = 1.7 ± 0.11), elongated-ellipsoid to cylindrical, in profile slightly curved or flattened on one side; in face view 3.9–4.9 (5.0) µm broad, elongated-ellipsoid to cylindrical, thin-walled, hyaline, non-amyloid. Basidia 18–26 × 7.0–9.6 µm, clavate, 4 - or 2 - spored. Pleurocystidia 20–32 × 5.5–8.1 µm, abundant, fusiform, utriform, thin-walled, hyaline. Cheilocystidia (28) 30–71 (152) × 17–29 µm, abundant, pyriform, with pedicellate spherical shapes, broad clavate, with short projections on the surface, occasionally branched, with pedicel 2.6–7.9 µm broad, branches 3.2–7.6 × 0.6–1.7 µm, thin-walled, hyaline. Pileipellis a cutis, with rameales-type structure, hyphal cells 2.1–14 µm broad. Stipitipellis a cutis, with numerous small protrusions on the hyphae, hyphal cells 2.7–14 µm broad, protrusions 1.5–7.1 × 1.0–5.8 µm, thin-walled. Caulocystidia 8.8–55 × 5.1–14 µm, abundant, cylindrical, surface with protuberances, occasionally branches, branches 1.4–7.4 × 0.9–3.2 µm, thin-walled. Clamp connections present.

Habitat.

Gregarious on decaying wood in mixed forests.

Distribution.

China.

Additional specimens examined.

China • Zhejiang Province: Lishui City, Qingtian County, Shigu Lake , 31 July 2021, Jun-Qing Yan, Bin-Rong Ke, Zhi-Heng Zeng, HFJAU 5718 .

Remarks.

Collybiopsis dentata is morphologically similar to C. californica , C. filamentipes , and C. foliiphila within the C. ramealis complex, all having a cutis of pileipellis with rameales-type structure and cheilocystidia with rameales-type structure. However, C. californica has narrower basidiospores (3.0–3.3 µm), smaller cheilocystidia (20–42 × 6–20 µm), and absence of pleurocystidia ( Desjardin 1987). Collybiopsis filamentipes has adnexed to subdecurrent lamellae, narrower basidiospores (2.5–3.5 µm), narrower cheilocystidia (8–18 µm), smaller caulocystidia (5–20 × 6–9 µm), cylindrical to digitate, and rarely branched ( Petersen and Hughes 2021). Collybiopsis foliiphila has narrower basidiospores (3.0–3.7 µm), lamellae often with rusty tawny to dark brick-colored spots, smaller cheilocystidia (28.6–31 × 9–12 µm), and absence of pleurocystidia ( Dutta et al. 2015).

Figures

Figure 4. Collybiopsis dentata. A – C. Basidiomata HFJAU 2586, Holotype; D. Basidiospore; E, F. Pleurocystidia; G – J. Cheilocystidia; K, L. Pileipellis; M. Stipitipellis; N. Stipe hyphae; O. Caulocystidia. All microscopic structures were observed in 5 % KOH, and 1 % Congo red was used as the stain. Scale bars: 10 mm (A); 5 mm (B); 10 mm (C); 10 µm (D); 20 µm (E, F); 30 µm (G – K); 10 µm (L); 30 µm (M); 10 µm (N, O).