Hypohelion P. R. Johnst.

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-

Hypohelion P. R. Johnst. , Mycotaxon 39: 221. 1990.

Type species.

Hypohelion scirpinum (DC.) P. R. Johnst. , Mycotaxon 39: 221. 1990.

Sexual morph.

Ascomata scattered to clustered, subcircular, elliptical or irregular, black, opening by an irregular longitudinal split. Covering stroma formed by dark brown (# 2 b 180 b) to black (# 000000), thick-walled angular cells, more or less uniform in thickness. Basal Covering stroma absent or formed by carbonized, thick-walled angular cells. Subhymenium consisting of textura intricata. Paraphyses filiform, not branched, with swollen tips. Asci ripening sequentially, clavate, thin-walled, J –, 8 - spored. Ascospores 0–1 septate, cylindrical, elliptical or slightly clavate, hyaline, covered by a gelatinous sheath.

Asexual morph.

Conidiomata, when present, round, dark brown (# 2 b 180 b) to black (# 000000), with a central ostiole. Conidiogenous cells cylindrical, tapering towards apex, hyaline. Conidia simple, oblong-elliptical to cylindrical, hyaline (Description based on Johnston 1990 b).

Notes.

Hypohelion was established by Johnston (1990 b) to accommodate two species, Hy. scirpinum and Hy. parvum P. R. Johnston. Both species are found on members of Cyperaceae Juss. growing in swampy habitats. Hypohelion can be distinguished from other genera by subcuticular ascomata; covering stroma consisting by dark brown, thick-walled, angular cells, more or less uniform in thickness; edge of the ascomata opening without differentiated cells; lacking a basal Covering stroma; and paraphyses with swollen apex ( Johnston 1990 b). Hypohelion durum Y. R. Lin, C. L. Hou & S. J. Wang ( Lin et al. 2004) and Hy. anhuiense Shuang Wang & C. L. Hou ( Wang et al. 2014 a) were added to this genus subsequently. However, Hy. durum differs from other Hypohelion species based on molecular phylogenetic data, morphology, and substrate. Hypohelion durum should therefore be excluded from the genus Hypohelion ( Wang et al. 2014 a) .