Tryblidiopsis yunnanensis Lan Zhuo & C. L. Hou, 2025

Zhuo, Lan, Wang, Hai-Qi, Zhang, Peng, Sui, Xiao-Nan, Guo, Mei-Jun, Wang, Shi-Juan & Hou, Cheng-Lin, 2025, New genera and species of coniferous twig-inhabiting Rhytismatales from China, IMA Fungus 16, pp. e 138790-e 138790 : e138790-

Tryblidiopsis yunnanensis Lan Zhuo & C. L. Hou sp. nov.

Figs 40 , 41

Etymology.

Referring to the name of the province (Yunnan) where the specimen was collected.

Diagnosis.

This new species is distinguished from other Tryblidiopsis species by its filiform ascospores each with 1–3 - septa, and occurrence on a non- Picea host.

Type.

CHINA, Yunnan Province, Lijiang, Laojunshan , alt. ca. 3200 m, on twigs of Tsuga chinensis (Franch.) Pritz. ( Pinaceae ), 11 Jul. 2007, C. L. Hou, HOU 487 ( BJTC 201203 , holotype) .

Sexual morph.

Ascomata on twigs, erumpent from the bark, scattered, not associated with pale areas. In surface view, ascomata round to irregular, 800–1100 µm, as seen from the side 350–550 µm high, black (# 000000), opening by irregular splits to expose a pale yellow hymenium. Lips absent. In median vertical section, covering stroma 70–100 μm thick near the center of ascomata, consisting of an outer layer of carbonized, angular to globose cells, and an inner layer of hyaline, angular to globose cells. Basal Covering stroma absent. Internal matrix of Covering stroma well-developed, consisting of hyaline hyphae and angular to globose cells. Subhymenium 20–40 µm thick, consisting of textura intricata and hyaline, angular to globose cells. Paraphyses aseptate, filiform, not branched, curved, sightly swollen at tips, 110–160 × 2–2.5 µm, covered by a thin gelatinous sheath. Asci ripening sequentially, clavate, apex obtuse, 90–135 × 11–18 µm, thin-walled, J –, 8 - spored. Ascospores 1–3 - septate, filiform, tapering at both ends, 45–90 × 2–4 μm, hyaline, covered by a thin gelatinous sheath.

Asexual morph.

Conidiomata and zone lines not seen.

Additional specimens examined.

CHINA, Yunnan Province, Lijiang, Xinzhu village , alt. ca. 2400 m, on twigs of Tsuga chinensis ( Pinaceae ), 20 Jul. 2013, C. L. Hou, HOU 1116 B ( BJTC 2013047 ) .

Distribution.

Known only from Yunnan Province, China.

Notes.

Wang et al. (2017) indicated that Tryblidiopsis species are host-specific and grow only on Picea spp. , but the new species Try. yunnanensis grows on Tsuga chinensis . Four species of Rhytismataceae are known from Tsuga spp , namely Coccomyces heterophyllae A. Funk , Coccomyces mertensianae Sherwood , Discocainia treleasei (Sacc.) J. Reid & A. Funk , and Therrya tsugae . However, for none of them molecular sequence data are available. Morphologically, Co. heterophyllae , Co. mertensianae , and D. treleasei differ from Try. yunnanensis by aseptate ascospores, and Th. tsugae differs from Try. yunnanensis by ascomata opening by a single longitudinal split. Usually, Tryblidiopsis spp. have fusiform to clavate ascospores and more or less stalked ascomata, whereas Try. yunnanensis has filiform ascospores and sessile ascomata. Sequence similarities of ITS rDNA between Try. yunnanensis and other sequences of Tryblidiopsis species are 86.63 % – 92.61 %, and nrLSU rDNA are 91.16 % – 97.72 %. Based on the differences of ascomata, ascospores, host and sequence similarities, it seems that a new genus should be erected to accommodate this species. To avoid establishing too many genera, however, we tentatively assign this species to Tryblidiopsis .

Figures

Figure 40. Tryblidiopsis yunnanensis (HOU 487 / BJTC 201203, holotype) a ascomata on a twig of Tsuga chinensis b, c mature ascomata. Scale bars: 1 mm (a); 500 μm (b, c).

Figure 41. Tryblidiopsis yunnanensis on Tsuga chinensis (HOU 487 / BJTC 201203, holotype) a part of an ascoma in vertical section b paraphyses, mature asci with ascospores, and immature ascus c liberated ascospores. Scale bars: 100 μm (a); 15 μm (b); 20 μm (c).