Labivalidus cunninghamiae 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-

Labivalidus cunninghamiae Lan Zhuo & C. L. Hou sp. nov.

Figs 17 , 18

Etymology.

Referring to the host genus Cunninghamia .

Diagnosis.

This new species is similar to Labivalidus jianchuanensis , but differs in having larger ascomata, larger ascospores, and paraphyses that are conspicuously swollen at their tips.

Type.

CHINA, Anhui Province, Anqing, Yuexi County, Wenao Forest Farm , 30.8050°N, 116.0885°E, alt. ca. 1020 m, on twigs of Cunninghamia lanceolata ( Cupressaceae ), 13 Apr. 2024, C. L. Hou, L. Zhuo, and X. N. Sui, HOU 2173 A ( BJTC 2024033 , holotype) .

Sexual morph.

Ascomata on young dead twigs, scattered, sometimes 2–3 clustered. In surface view, ascomata elliptical to broadly elliptical, 900–1600 × 480–880 μm, black (# 000000), opening by a longitudinal split. Lips well developed, creamy white (# fffeea). In median vertical section, ascomata intraepidermal. Covering stroma 50–90 μm thick near the center of the ascomata, extending to the basal Covering stroma, consisting of an outer layer of host cuticle, and an inner layer of carbonized, thick-walled, angular to globose cells. Lip cells septate, cylindrical, 6–10 × 2–4 μm, hyaline. Basal Covering stroma 20–30 µm thick, consisting of carbonized, thick-walled, angular to globose cells. A space triangular in vertical section between the covering stroma and the basal Covering stroma at the margin of the ascoma is filled with thin-walled, hyaline cells. Subhymenium 20–30 µm thick, consisting of textura intricata. Paraphyses filiform, not branched, conspicuously swollen to 2–3 μm diam. at their tips, 150–195 × 1 µm, covered by a thin gelatinous sheath. Asci ripening sequentially, cylindrical, with rostrate apex, 130–180 × 13–15 μm, thin-walled, J –, 8 - spored. Ascospores aseptate, filiform, 100–125 × 3–4 μm, hyaline, covered by a 1–2 μm thick, gelatinous sheath.

Asexual morph.

Conidiomata and zone lines not seen.

Additional specimens examined.

CHINA, Anhui Province, Anqing, Yuexi County, Yaoluoping Nature Reserve , 30.8050°N, 116.0885°E, alt. ca. 1020 m, on twigs of Cunninghamia lanceolata ( Cupressaceae ), 13 Apr. 2024, C. L. Hou, L. Zhuo, and X. N. Sui, HOU 2166 ( BJTC 2024026 ) .

Distribution.

Known only from Anhui Province, China.

Notes.

In the phylogenetic tree, the molecular sequences of Labivalidus cunninghamiae form a clade sister to La. jianchuanensis . Labivalidus jianchuanensis differs from La. cunninghamiae by having smaller ascomata (500–750 (– 920) µm × 400–520 µm), smaller ascospores (65–90 µm × 1–1.5 (– 2) µm), and tips of paraphyses that are not swollen.

Figures

Figure 17. Labivalidus cunninghamiae (HOU 2173 A / BJTC 2024033, holotype) a ascomata on a twig of Cunninghamia lanceolata b, c Mature ascomata. Scale bars: 2 mm (a); 500 μm (b, c).

Figure 18. Labivalidus cunninghamiae on Cunninghamia lanceolata (HOU 2173 A / BJTC 2024033, holotype) a part of an ascoma in vertical section, lips well developed b paraphyses, mature asci with ascospores, and immature ascus c liberated ascospores. Scale bars: 100 μm (a); 10 μm (b); 20 μm (c).