Cryptococcomyces occultus 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-

Cryptococcomyces occultus Lan Zhuo & C. L. Hou sp. nov.

Figs 10 , 11

Etymology.

Occultus (Latin) = hidden, referring to the ascomata surface being concolorous with the surface of the substrate.

Diagnosis.

This new species is similar to Cryptococcomyces carbostomaticus , but differs by the absence of hyaline textura prismatica as innermost layer of the covering stroma.

Type.

CHINA, Yunnan Province, Kunming, Jiaozi Mountains , 26.0861°N, 102.8492°E, alt. ca. 3810 m, on twigs of Juniperus squamata ( Cupressaceae ), 23 Jun. 2021, C. L. Hou, M. J. Guo, and H. Zhou, HOU 1861 A ( BJTC 2021172 , holotype) .

Sexual morph.

Ascomata on twigs, scattered, not associated with pale areas. In surface view, ascomata elliptical to round, 1600–2100 × 1400–2100 μm, concolorous with surface of substrate, erumpent through host epidermis, opening by irregular splits to expose pale yellow (# ffff 9 d) hymenium. Lips absent. In median vertical section, ascomata intracortical. Covering stroma 125–145 μm thick near the center of the ascomata, extending to the basal Covering stroma, consisting of an outer layer of remains of host cortex and an inner layer of carbonized, angular to globose cells. Excipulum present, formed by marginal paraphyses. Basal Covering stroma poorly developed, consisting of carbonized, angular to globose cells. Internal matrix of Covering stroma 95–130 µm thick, consisting of hyaline, thin-walled, angular cells and short hyphae embedded in gelatinous mucus. Subhymenium 20–30 µm thick, consisting of hyaline textura porrecta. Paraphyses aseptate, filiform, not branched, slightly curved at tips, 130–140 × 1–2 µm, covered by a thin gelatinous sheath. Asci ripening sequentially, clavate, apex obtuse to acute, 80–120 × 6–8 μm, stalked, thin-walled, J –, 8 - spored. Ascospores aseptate, filiform, 30–40 × 1 μm, hyaline.

Asexual morph.

Conidiomata and zone lines not observed.

Additional specimens examined.

CHINA, Yunnan Province, Lijiang, Laojunshan , 26.6433°N, 99.7675°E, alt. ca. 3500 m, on twigs of Juniperus squamata ( Cupressaceae ), 16 Jul. 2020, C. L. Hou, M. J. Guo and Q. T. Wang, HOU 1613 ( BJTC 2020055 ) ; Kunming, Jiaozi Mountains , 26.0841°N, 102.8405°E, alt. ca. 3570 m, on twigs of J. squamata , 23 Jun. 2021, C. L. Hou, M. J. Guo and H. Zhou, HOU 1838 ( BJTC 2021149 ) .

Distribution.

Known only from Yunnan Province, China.

Notes.

Phylogenetically, molecular sequences of Cry. occultus forms a distinct clade with high support values (MLB = 98 %, MPB = 97 %, PP = 1.00) together with the sequences of Cry. carbostomaticus , Cry. niger , and Cryptococcomyces sp. 1 . However, the values of similarity of the ITS rDNA sequences of Cry. occultus with Cry. carbostomaticus , Cry. niger , and Cryptococcomyces sp. 1 are 97 %, 96 %, and 98 %, respectively. Morphologically, Cry. niger differs from Cry. occultus by black, smaller (800–1000 × 900–1200 µm) ascomata, which protrude from the surface of the host; Cry. carbostomaticus differs from Cry. occultus by the presence of hyaline textura prismatica in the innermost layer of the covering stroma. Unfortunately, ascomata in the specimen of Cryptococcomyces sp. 1 are not mature enough to observe microscopic features. Cryptococcomyces occultus is morphologically similar to Coccomyces lijiangensis on Pinus armandii ( Pinaceae ), but Co. lijiangensis has a well-developed basal Covering stroma (900–1200 µm), and the internal matrix of the Covering stroma consists of hyaline hyphae and numerous crystals variable in shape and size. Therefore, based on phylogenetic and morphological differences, Cry. occultus is designated as a new species. It is the type of the genus Cryptococcomyces because it possesses the most typical traits of ascomata covered by bark.

Figures

Figure 10. Cryptococcomyces occultus (HOU 1861 A / BJTC 2021172, holotype) a ascomata on a twig of Juniperus squamata b, c mature ascomata. Scale bars: 2 mm (a); 500 μm (b); 1 mm (c).

Figure 11. Cryptococcomyces occultus on Juniperus squamata (HOU 1861 A / BJTC 2021172, 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).