Helianthoconium helianthosporum X. Yu. Zhang, Q. Y. Zhang & B. Fan, 2025

Zhang, Xiu-Yu, Zhang, Qiu-Yue, Li, De-Wei, Sun, Jing-Zu & Fan, Ben, 2025, Novel endophytic fungi from Pinus: introducing three new genera and six new species within Capnodiales (Ascomycota, Dothideomycetes) sensu lato, IMA Fungus 16, pp. e 175931-e 175931 : e175931-

Helianthoconium helianthosporum X. Yu. Zhang, Q. Y. Zhang & B. Fan sp. nov.

Fig. 10

Etymology.

Derived from the Latin word “helianthus,” indicating that it is named for distinctive morphology of its conidia, which closely resemble sunflower seeds.

Type.

CHINA • Jiangsu Province, Nanjing, Nanjing Forestry University, Baima Campus , fungal endophyte from Pinus densiflora , May 2023, Ben Fan and Xiuyu Zhang, NF 684 ( holotype HMAS 352957 , culture ex-type CGMCC 3.28953 ) .

Description.

Mycelium composed of hyaline, smooth or warty, aseptate, flexuous, branched, slender, 1.2–2.8 μm diam. Asexual state: Conidiophores erect, solitary, arising from hyphae, 2–15 - septate, straight to flexuous, subcylindrical, brown, smooth, stout, unbranched, (57.4 –) 63.3–122.6 (– 161.6) × (2.3 –) 3.1–4.7 (– 4.7) μm. Conidiogenous cells terminal, pale brown to brown, smooth, subcylindrical, terminal, connected in series, (4.2 –) 5.4–10.3 (– 11.9) × (2.7 –) 3.0–3.9 (– 4.1) μm. Conidia terminal and lateral, aseptate, smooth, brown, sunflower seed-shaped, base truncate, (6.0 –) 6.9–8.2 (– 8.5) × (3 –) 3.5–4 (– 5) μm. Sexual state unknown.

Culture characteristics.

Colonies on MEA slow-growing, velvety to hairy, with entire margin; surface dark olivaceous-grey. On SNA and OA, the colonies appear off-white (Fig. 10 A – C ). The optimal temperature for growth was 20–25 ° C, reaching 4–5 mm diam after 10 days on MEA. No growth was observed at 5 ° C and 35 ° C.

Additional specimen ( paratype) examined.

CHINA • Jiangsu Province, Nanjing, Nanjing Forestry University, Baima Campus , fungal endophyte from Pinus densiflora , May 2023, Ben Fan and Xiuyu Zhang, paratype NF 884 .

Notes.

In the phylogenetic analyses of Capnodiales (Fig. 1 ) and Dissoconiaceae (Fig. 2 ), the isolate of Helianthoconium helianthosporum formed a well-supported clade within Dissoconiaceae ( ML / BI = 100 / 1.00). BLAST analysis of the ITS sequence of NF 684 against NCBI reveals a 10.78 % (51 / 473 bp) difference from its closest known relative, indicating a clear genetic distinction. Although consistently placed within Dissoconiaceae , Helianthoconium helianthosporum differs from other genera in this family by its sunflower seed-shaped conidia (vs. broadly ellip soidal to globose in Globoramichloridium and cylindrical in Paradissoconium ) and shorter conidiogenous cells (4.2–11.9 μm vs. 15–45 μm in Paradissoconium narthecii ). Based on these phylogenetic and well-defined morphological differences, we propose the new genus Helianthoconium , with H. helianthosporum as the type species.

Figures

Figure 1. Phylogram of Capnodiales s. lat. based on a combined ITS + nLSU + RPB 2 + TEF 1 sequence dataset, inferred from maximum likelihood and Bayesian analyses. Numbers above the branches indicate ML bootstrap values (left, ≥ 50 %) and Bayesian posterior probabilities (right, ≥ 0.90). The isolates from this study are marked in blue.

Figure 2. Phylogram of Dissoconiaceae based on a combined ITS + nLSU sequence dataset, inferred from maximum likelihood and Bayesian analyses. Numbers above the branches indicate ML bootstrap values (left, ≥ 50 %) and Bayesian posterior probabilities (right, ≥ 0.90). The isolates from this study are marked in blue.

Figure 10. Morphological features of Helianthoconium helianthosporum (isolate NF 684). A – C Colonies on MEA (A), SNA (B) and OA (C) at 25 ° C for 10 days. A shown on a 90 mm Petri dish. D – H Conidiophores (a), conidiogenous cells (b), and conidia (c). Scale bars: 5 mm (B, C); 10 μm (D – H).