Hypoderma cunninghamiicola Peng Zhang & S. J. Wang, 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-

Hypoderma cunninghamiicola Peng Zhang & S. J. Wang sp. nov.

Figs 13 , 14

Etymology.

Referring to the host genus Cunninghamia .

Diagnosis.

This new species is similar to Hypoderma rubi (Pers.) De Not. , but differs by a thicker covering stroma and a basal Covering stroma, longer asci and longer ascospores.

Type.

CHINA, Anhui Province, Yaoluoping National Nature Reserve, Dachuanling , alt. ca 800 m, on one year old twigs or needles of Cunninghamia lanceolata ( Cupressaceae ), 9 Sept. 2023, S. J. Wang, L. Zhen, X. Y. Li, and Y. L. Li, L 4648 ( AAUF 70756 , holotype) .

Sexual morph.

Ascomata on one-year twigs and needles, scattered, sometimes 2 to 3 clustered. In surface view, ascomata elliptical to elongated-elliptical, 750–1950 × 275–375 µm, dark brown (# 2 b 180 b) to black (# 000000), sometimes dark brown in the center, gray (# 787870) at the edge, shiny, with a conspicuous black perimeter line, opening by a single longitudinal split. Lips well developed, yellow-brown (# f 2 d 98 d). In median vertical section, ascomata subcuticular. Covering stroma 40–60 μm thick near the center of ascomata, gradually thinner towards the edge, connecting to the basal Covering stroma, consisting of an outer layer of host tissue, and an inner layer of dark brown, thick-walled textura angularis. Lips cells 3–4 - septate, thin-walled, cylindrical, radially arranged, 20–28 × 3–4 µm, hyaline to yellow-brown. Basal Covering stroma 7–15 µm thick, consisting of carbonized, thick-walled, angular cells. Triangular space in vertical section between the covering stroma and the basal Covering stroma at the margin of the ascoma is filled with hyaline, thin-walled, angular cells. Subhymenium 5–15 µm thick, consisting of hyaline textura porrecta. Paraphyses filiform, sometimes branched, not swollen or slightly swollen at tips, 140–160 × 1–1.2 µm, covered by a thin gelatinous sheath. Asci ripening sequentially, clavate, apex subtruncate or rounded, 70–130 × 12–15 µm, thin-walled, J –, 8 - spored. Ascospores aseptate, cylindrical, elliptical or cylindrical-clavate, 14–22 × 3.5–5 μm, hyaline, covered by a ca. 1 μm thick gelatinous sheath.

Asexual morph.

Conidiomata rounded or elliptical, brown (# 48240 a), slightly raising the substrate surface, opening by 1–2 ostioles. In median vertical section, conidiomata subcuticular. Upper wall absent. Basal wall poorly developed, black-brown, 3–5 μm thick, consisting of angular cells. Conidia and zone lines not seen.

Additional specimens examined.

CHINA, Anhui Province, Yaoluoping National Nature Reserve, Dachuanling , alt. ca. 800 m, on one year old twigs or needles of Cunninghamia lanceolata ( Cupressaceae ), 9 Sept. 2023, S. J. Wang, L. Zhen, X. Y. Li, and Y. L. Li, L 4647 ( AAUF 70755 ) .

Distribution.

Known only from Anhui Province, China.

Notes.

Phylogenetic analysis reveals that, with the exception of H. berberidis , H. minteri , H. caricis , and H. junipericola , other species of Hypoderma are divided into two distant clades. The sequences of the new species, along with several others, form a highly supported clade (MLB = 100 %, MPB = 81 %, PP = 0.99; Clade 9, Fig. 1 ). Morphologically, H. cunninghamiicola is similar to the type of Hypoderma , H. rubi , but the latter has a thicker covering stroma (50–80 μm), a thicker basal Covering stroma (10–15 μm), longer asci (110–160 μm) and longer ascospores (15–28 μm) ( Johnston 1990 a). The host range of H. rubi is broad, and it has been reported on both broadleaved plants and conifers (e. g. Cunninghamia lanceolata ). Considering its saprobic nature, these reports are plausible. However, further research incorporating molecular data is required to confirm whether these occurrences truly represent H. rubi or distinct, cryptic species.

Figures

Figure 1. Phylogenetic tree derived from maximum likelihood analysis of combined ITS, nrLSU, and mtSSU rDNA sequences of Rhytismatales, using Cudoniella clavus (AFTOL-ID 166) and Pezicula carpinea (KUS-F 51029) as outgroups. Bootstrap support values for ML analysis (MLB) and MP analysis (MPB) greater than 70 % and Bayesian posterior probabilities (PP) greater than 0.95 are given above the nodes. Names of new species and a new combination are written in bold. Species name T – Type species; Species name H – Holotype.

Figure 13. Hypoderma cunninghamiicola (L 4648 / AAUF 70756, holotype) a ascomata on a twig of Cunninghamia lanceolata b, c mature ascomata. Scale bars: 1000 μm (a); 500 μm (b, c).

Figure 14. Hypoderma cunninghamiicola on Cunninghamia lanceolata (L 4648 / AAUF 70756, holotype) a part of an ascoma in vertical section b paraphyses, mature asci with ascospores, and immature ascus c liberated ascospores. Scale bars: 50 μm (a); 20 μm (b, c).