Helicosporium qixianlingense S. Bai, L. J. Chen, & J. Ma, 2025

Bai, Song, Wang, Fang, Wan, Su-Ran, Lv, Xiao-Kang, Chen, Li-Jun, Wu, Rong & Ma, Jian, 2025, Two novel Helicosporium species (Tubeufiaceae, Tubeufiales) from southern China based on morphological and molecular evidence, MycoKeys 124, pp. 159-176 : 159-176

Helicosporium qixianlingense S. Bai, L. J. Chen, & J. Ma sp. nov.

Fig. 2

Etymology.

‘‘ qixianlingense ” refers to the place ‘‘Qixianling Hot Spring National Forest Park,” from where the holotype was collected.

Holotype.

GZAAS 25–0671

Description.

Saprobic on decaying wood in a terrestrial habitat. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate superficial, effuse, gregarious, yellowish green to brown. Mycelium partly immersed, partly superficial, composed of pale brown to brown, branched, septate, guttulate, smooth hyphae. Conidiophores 132–144 × 3.7–4.8 μm (x ̄ = 139 × 5.5 μm, n = 30), macronematous, mononematous, erect, cylindrical, long, straight or slightly flexuous, simple, septate, brown to dark brown at base, paler towards the apex, smooth, thick-walled. Conidiogenous cells 4.5–10 × 3–4.4 μm (x ̄ = 8 × 3.6 μm, n = 30), holoblastic, monoblastic, or polyblastic, integrated, intercalary, cylindrical, denticulate, arising laterally from the lower portion of conidiophores as tiny bladder-like protrusions (3–4 µm long, 2–2.7 µm wide), with each bearing 1–2 tiny sporogenous conidiogenous loci, hyaline to pale brown, smooth. Conidia solitary, pleurogenous, helicoid, tapering towards the rounded ends, developing on bladder-like protrusion, 11.7–12 μm in diameter, and conidial filament 1.2–2.1 μm wide (x ̄ = 11.9 × 1.7 μm, n = 30), 72.5–84 μm long (x ̄ = 76.5 μm, n = 35), up to 4 1 / 2 times, becoming loosely coiled when the conidia are young and not becoming loose when mature in water, indistinctly multi-septate, guttules, hyaline, smooth-walled.

Culture characteristics.

Conidia germinating on PDA within 11 hours, producing germ tubes from the conidial body. Colony on PDA reaching 3.2 cm in diameter after 44 days at room temperature (approximately 25 ° C), circular or irregular, umbonate, with an undulate margin, and pale brown to light pinkish in color.

Material examined.

• China, Hainan Province, Baoting Li and Miao Autonomous County, Qixianling Hot Spring National Forest Park , on decaying wood in a terrestrial habitat, 2 November 2024, Jian Ma Q 23 ( GZAAS 25–0671 , holotype), ex-type living cultures GZCC 25–0641 ; Ibid., Q 39 ( GZAAS 25–0672 , paratype), living culture GZCC 25–0642 .

Notes.

In the phylogenetic analyses (Fig. 1 ), our isolates ( GZCC 25–0641 and GZCC 25–0642 ) formed a sister clade to Helicosporium hainanense ( GZAAS 22–2006 ) with 93 % MLBS and 1.00 BYPP support. However, nucleotide polymorphisms in the ITS, LSU, tef 1 - α, and rpb 2 sequence data between GZCC 25–0641 and H. hainanense ( GZCC 22–2006 ) revealed nucleotide differences of 11 / 432 bp (2.5 %, with no gaps), 5 / 814 bp (0.6 %, with no gaps), 11 / 906 bp (1.2 %, with no gaps), and 39 / 1,045 bp (3.7 %, with no gaps), respectively. Furthermore, Helicosporium qixianlingense ( GZAAS 25–0671 ) differs from H. hainanense ( GZAAS 22–2006 , ex-type) by its longer conidia (72.5–84 μm vs. 55–60 μm), narrower conidial filament (1.2–2.1 μm vs. 2–3 μm), and more coiled times (up to 4 1 / 2 times vs. 2 1 / 4 –2 3 / 4 μm times) ( Lu et al. 2022 a). Therefore, based on both molecular and morphological evidence, we introduce Helicosporium qixianlingense as a novel species.

Figures

Figure 1. Phylogenetic tree generated using RAxML analysis based on the concatenated ITS, LSU, tef 1 - α, and rpb 2 sequence data. Bootstrap support values (MLBS) ≥ 75 % and Bayesian posterior probabilities (BYPP) ≥ 0.95 are indicated near the nodes as MLBS / BYPP, respectively. A hyphen (–) denotes support values below 75 % for ML and posterior probabilities below 0.95 for BI. Botryosphaeria agaves (MFLUCC 10–0051) and B. dothidea (CBS 115476) were used as outgroups. Ex-type strains are marked with “ T, ” and newly obtained isolates are highlighted in bold black font.

Figure 2. Helicosporium qixianlingense (GZAAS 25–0671, holotype). a, b. Colonies on the host surface; c – f. Conidiophores and conidiogenous cells; g – l. Conidiogenous cells; m – q. Conidia; r. A germinated conidium; s, t. Colonies on PDA from above and below after 44 days of incubation at room temperature. Scale bars: 30 μm (c – f); 10 μm (r); 5 μm (g – q).