Pseudoplectania aureonigrescens S. A. Chen, D. Li & G. F. Mou, 2025

Liu, Jin Rong, Li, Deng, Chen, Si Ang, Zhang, Yan Cheng, Mou, Guang Fu, Liu, Yan, Zhou, Guang Rong, Tan, Zhou Rong & Zhang, Jian Hua, 2025, Species diversity and systematic taxonomy of Sarcosomataceae (Ascomycota, Pezizales), with an emphasis on subtropical regions of China, MycoKeys 121, pp. 21-65 : 21-65

Pseudoplectania aureonigrescens S. A. Chen, D. Li & G. F. Mou sp. nov.

Figs 9 , 10 , 11

Etymology.

The specific epithet “ aureonigrescens ” refers to the yellowish to orangish color of hymenium surface when young, which changes to grayish black at maturity.

Diagnosis.

Differs from other known Pseudoplectania species by combination of the following features: sessile ascomata, bowl-shaped, petal-shaped to irregular apothecium up to 25 mm in diameter, hymenium surface yellow-colored when young, changing to grey or black when mature; one type of external hairs straight to distinctly curved or flexuous (not coiled), paraphyses with a mostly straight and rarely diverticulated tip, crystals in the hymenium up to 19.5 μm wide, and smooth ascospores without a gelatinous sheath.

Holotype.

China • Fujian Province, Fuzhou City, Cangshan District, Fujian Agriculture and Forestry University, Baizhu Garden , 26°08'N, 119°24'E, ca 50 m alt., on senescing to dead rhizomes of bamboo (probably Oligostachyum lubricum ) exposed outside mossy soil walls in a planted bamboo forest, 29 Oct. 2024, D. Li & S. A. Chen (CSA-798, IBK, holotype!) (ITS: PQ 895821 ; nrLSU: PQ 863683 ; rpb 1: PV 247121 ; tef 1-α: PV 296005 ).

Description.

Ascomata tiny to small, sessile. Apothecium bowl-shaped, petal-shaped to irregular, 5–24 mm in diameter, up to 10 mm high; margin entire and involute, cracked after drying. Hymenium surface yellow-tan (2 A 6), dirty orange (4 B 8) to golden brown (5 C 7) when young, glabrous, dull, plum grey (8 E 5), wine grey (9 E 3) to off-black (4 F 8) at maturity, color unchanging when bruised, cracked after drying. External surface velvety to strigose, off-black (4 F 8), densely covered with tomentum or short bristles, without ridges or crests. Stipe absent (Fig. 9 f ). Subiculum off-black (4 F 8), cotton-like, dense, soft. Flesh thin, conch grey (22 B 1), cloud grey (15 C 1) to pewter grey (10 E 1). Odor and taste not special. Anamorph not observed.

External hairs of one type, hyphoid, septate, cylindrical, straight to distinctly curved or flexuous (not coiled), brass brown (1 C 7), 4–9.5 μm in diameter, with slightly thick to thick walls, up to 2 μm thick, tips rounded, sometimes split to two protuberances, unbranched, surface smooth to slightly rough (Figs 10 b , 11 e ). Ectal excipulum of a texture angularis, made up of properly to distinctly thick-walled (up to 3 μm) cells, measuring 5.5–23 × 3.5–13 μm, sub-hyaline, tawny (4 C 5), masala chai brown (4 D 7) to dark brown (5 E 8), and dull black (18 F 8), not or very slightly encrusted, thick-walled, up to 180 μm thick (Figs 10 a, f , 11 h ). Medullary excipulum of loose textura intricata immersed in a gelatinous matrix, up to 335 μm thick, with hyphae septate, subhyaline or pale yellow (1 A 5), thin-walled, flexuous, branched, 2–4 (6) μm wide, tawny (4 C 5) to light brown (4 C 7), dark coffee brown (4 E 8) at low magnification (× 100, Fig. 10 a, e ). Subhymenium of a dense textura intricata of septate hyphae, 2–4 μm wide, thin-walled, concolor with medullary excipulum, up to 80 μm thick, dark coffee brown (4 E 8) to dark brown (5 E 8) at low magnification (Fig. 10 a ). Asci cylindrical, operculate, with a curved or flexuous, tapered base, 8 - spored, 195–335 × 10.5–14 μm, constricts at the junction of two ascospores, non-amyloid, apex mostly rounded, sometimes with a conical, eccentric, or non-eccentric protrusion (Figs 10 g – i, n, o , 11 a, b ). Ascospores uniseriate, smooth, with thick walls, globose to subglobose, sub-hyaline to pale yellow (1 A 5), [60 / 4 / 2] (8.5) 9.5–11.5 (14) × (8.5) 9–11 (14) μm, Q value = (0.95) 1–1.1 (1.13) including the spore wall, non-amyloid, with or without one to multiple, globose to subglobose contents (Figs 10 p – s , 11 g ). Paraphyses abundant, filiform, not or slightly extending the length of asci, septate, subcylindrical, simple to bifurcate, straight to slightly curved, sometimes anastomosed, branched both from the lower part and tips, dark khaki brown (5 D 6) to dark coffee brown (4 E 8) due to amorphous pigments, (1) 1.5–3 μm in diameter, tips rounded to finger-shaped, rarely with few protuberances or notches, mostly straight, sometimes slightly enlarged or curved, unbranched or branched 1–2 times (Figs 10 j, k , 11 d ). Hymenial hairs cylindrical, long as the paraphyses, non-septate but with a single septum in the basal part, (1.5) 2–3.5 μm in diameter, concolor with the paraphyses due to the homogeneous pigments, tips rounded, straight to slightly curved, unbranched (Figs 10 l, m , 11 c ). Subiculum dark coffee brown (4 E 8) to dark brown (5 E 8), septate, thick-walled, straight to curved or flexuous, mostly unbranched, rarely branched once, not encrusted, 4–6.5 μm in diameter, with a rounded tip (Figs 10 c , 11 f ). Crystals in the hymenium rectangle to angular, sometimes cracked, roughly parallel to other elements in hymenium, concolor with the paraphyses, mainly of two types, although intermediates forms may exist: 1) thin, 1.9–4.5 μm in diameter, up to 24.5 μm long; 2) thick, 7–19.5 μm in diameter, up to 27.5 μm long (Fig. 10 d ).

Habitat.

Growing in scattered to gregarious groups on senescing to dead rhizomes of bamboo (probably Oligostachyum lubricum ) exposed outside mossy soil walls in bamboo forests.

Geographic distribution.

So far, only known from Fujian Province, China.

Other material examined.

China • Fujian Province, Fuzhou City, Cangshan District, Fujian Agriculture and Forestry University, Baizhu Garden , 26°08'N, 119°24'E, ca 50 m alt., on senescing to dead rhizomes of bamboo exposed outside mossy soil walls in a planted bamboo forest (probably Oligostachyum lubricum ), 12 Nov. 2023, S. A. Chen, CSA- 797 ( IBK!) (ITS: PQ 863322 ; LSU: PQ 863491 ; tef 1-α: PV 296004 ) .

Notes.

In the phylogenetic analyses, Pseudoplectania aureonigrescens clustered with Ps. affinis and Ps. globospora in clade III. The sessile ascomata with entire margin, velvety, rough, blackish external surface, dark hymenium surface at maturity, and globose to subglobose ascospores without gelatinous sheath make them easily confused ( Carbone et al. 2014 a; Zeng et al. 2024). But it can still be recognized by some distinguishing characters. With respect to Ps. affinis , Ps. aureonigrescens has variously shaped apothecium, dull hymenium surface at maturity, hymenium with crystals, existing obviously curved or flexuous external hairs, and paraphyses rarely with protuberances or notches. Compared with Ps. globospora , Ps. aureonigrescens can be distinguished by its variously shaped apothecium, one-typed external hairs, smaller cells in ectal excipulum (5.5–23 × 3.5–13 μm vs. 17-22 × 14-17 μm), existing crystals in hymenium, slightly smaller ascospores (9.5–11.5 × 9–11 μm vs. 10.5–12.5 × 9.8–13.5 μm), and also by its lignicolous habitat. Also, the lineage belongs to the newly established species, obtains strong support, and is enough to separate itself from its relatives by genetic distance.

Ecologically, Pseudoplectania aureonigrescens and Ps. mystica , teleomorphs of both, share a similar habitat and are geographically close in distribution, growing groups on senescing to dead rhizomes of bamboo ( Lin et al. 2024). It is also notable that Ps. aureonigrescens shares similarities with Ps. mystica in its sessile ascomata, velvety, dark external surface, crystals in hymenium, existing wavy or flexuous external hairs, paraphyses rarely with protuberances or notches. However, besides its distant of genetic, this new species is clearly differentiated by ascomata of various shapes, dull hymenium surface when mature, existing branched subiculum, a lack of crystals in ectal excipulum, and slightly smaller ascospores without sheath (9.5–11.5 × 9–11 μm vs. 11–13 × 10.5–12 μm).

Figures

Figure 9. Ecological and macroscopic characteristics of Pseudoplectania aureonigrescens, photos by S. A. Chen & D. Li; c – e. from holotype CSA- 798 (IBK!); f – j. from CSA- 797 (IBK!). a. Habitat where the specimen CSA- 798 (IBK!) grew (the white arrow indicates the growth site of ascomata), senescing or dead rhizomes of bamboo exposed outside mossy soil walls; b. Habitat where the specimen CSA- 797 (IBK!) grew (white arrows indicate growth sites of ascomata), a planted bamboo forest; c – e. Mature ascomata with a smooth, greyish-black hymenium; f. Off-black external surface covered with abundant tomenta; g. Details of the hairy external surface; h. Vertical section including greyish thin flesh; i, j. Young ascomata with discoid to petal apothecium, dirty orange hymenium, and velvety to strigose external surface. Scale bars: 10 mm (c, e); 5 mm (d, f, h – j); 2 mm (g).

Figure 10. Microscopic structures of Pseudoplectania aureonigrescens, photos by S. A. Chen, from holotype CSA- 798 (IBK!). a. Cross section through apothecia; b. External hair; c. Hypha of subiculum; d. Hymenium with crystals (white arrows indicate the position of crystals); e. Medullary excipulum in Congo red; f. Ectal excipulum in Congo red; g. Ascus with mature ascospores in Meltzer’s reagent; h. Empty ascus with opened operculum in Congo red; i. Immature ascus without visible ascospores in Congo red; j, k. Paraphyses in Congo red; l, m. Hymenial hair in Congo red (the yellow arrow in m indicates the basal septa of the hymenium hair); n. Rounded apex of asci in Congo red; o. Apex of asci with a conical eccentric protrusion; p, q. Ascospores in distilled water; r, s. Ascospores in Meltzer’s reagent. Scale bars: 100 μm (a); 50 μm (b – i, k, m); 20 μm (j); 10 μm (l, n – s).

Figure 11. Microscopic structures of Pseudoplectania aureonigrescens, drawing by S. A. Chen, from holotype CSA- 798 (IBK!). a. An ascus with 8 ascospores; b. Empty ascus with its operculum; c. Hymenium hairs; d. Paraphyses; e. External hairs; f. Hypha of subiculum; g. Ascospores; h. A part of ectal excipulum. Scale bars: 50 μm (a – f sharing same bars); 10 μm (g, h).