Pseudococcomyces 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-

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

Figs 28 , 29

Etymology.

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

Diagnosis.

This new species is similar to Coccomyces irretitus Sherwood , but Pseudococcomyces yunnanensis has paraphyses that are coiled, interwoven at their tips and lacks interwoven hyaline periphysoids.

Type.

CHINA, Yunnan Province, Lijiang, Laojunshan , 26.6434°N, 99.7676°E, alt. ca. 3930 m, on twigs of Larix speciosa W. C. Cheng & Y. W. Law ( Pinaceae ), 16 Jul. 2020, C. L. Hou, M. J. Guo, and H. Zhou, HOU 1574 ( BJTC 2020012 , holotype) .

Sexual morph.

Ascomata on twigs, erumpent, scattered, not associated with pale areas. In surface view, ascomata round to irregularly elongate, 750–1000 µm diam., black (# 000000), erumpent from bark, opening by radial splits to expose a yellow (# ffd 400) hymenium. Lips absent. In median vertical section, covering stroma 50–70 μm thick near the center of the ascomata, not extending to the base, consisting of an outer layer of remains of the host cortex, an inner layer of carbonized, angular to globose cells, and an innermost layer of pigmented angular to globose cells. Basal Covering stroma absent. Internal matrix of Covering stroma 250–300 µm thick, consisting of hyaline, thin-walled, angular cells and interwoven short hyphae. Subhymenium 30–50 µm thick, consisting of thin-walled, angular cells. Paraphyses aseptate, filiform, strongly circinate, not swollen at tips, 145–160 × ca. 1 µm. Asci ripening sequentially, clavate, apex bluntly pointed, 105–155 × 12–18 µm, stalked, thin-walled, J –, 8 - spored. Ascospores aseptate, filiform-clavate, tapering towards base, 40–55 × 1–2 μm, hyaline, covered by a 3–5 μm thick gelatinous sheath.

Asexual morph.

Conidiomata and zone lines not seen.

Additional specimens examined.

CHINA, Yunnan Province, Lijiang, Laojunshan , 26.6434°N, 99.7676°E, alt. ca. 3930 m, on twigs of Larix speciosa ( Pinaceae ), 26 Jul. 2024, C. L. Hou, L. Zhuo, and X. N. Sui, HOU 2306 ( BJTC 2024156 ) .

Distribution.

Known only from Yunnan Province, China.

Notes.

In the phylogenetic tree, the sequences of P. yunnanensis form a distinct clade. Morphologically, P. yunnanensis is closely related to Co. irretitus ; because both species grow on twigs of Larix spp. However, Co. irretitus has branched, netlike interwoven hyaline periphysoids immersed in a gel at the inner side of the covering stroma, and the tips of its paraphyses are weakly circinate ( Sherwood 1980). Therefore, P. yunnanensis is considered to be a new species.

Figures

Figure 28. Pseudococcomyces yunnanensis (HOU 1574 / BJTC 2020012, holotype) a ascomata on a twig of Larix speciosa b, c mature ascomata. Scale bars: 2 mm (a); 500 μm (b, c).

Figure 29. Pseudococcomyces yunnanensis on Larix speciosa (HOU 1574 / BJTC 2020012, 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); 10 μm (b, c).