Collariella hongheensis X.F. Liu, Karun. & Tibpromma sp. nov.
Index Fungorum number: IF 902097; Mycobank number: MB 902097; Facesoffungi number: FoF 15838, Fig. 1
Etymology – Named after the location Honghe, where the fungus was first discovered.
Endophytic on Mangifera indica leaves. Sexual morph: Produced on 60 days old PDA culture, Vegetative hyphae hyaline, septate, branched, smooth-walled, 1–5 µm diam wide. Ascomata 250–500 µm high, 200–300 µm diam., superficial, subglobose, oval to fusiform, pale mouse grey to black, with rounded base, ostiolate, neck inconspicuous. Ascomatal wall brown, textura globulosa to angularis in surface view. Terminal hairs arising from the apical collar, conspicuously rough, dark brown, septate, erect in the lower part, 2.5–6 μm near the base, spirally coiled in the upper part. Lateral hairs seta-like, tapering and fading towards the tips. Hamathecium 2–4 μm wide (x̄=3.19 μm, n=20), hyaline, septate paraphyses. Asci 30–63.5 × 5–13 μm (x̄=42.30×8.65 μm, n=30), fasciculate, clavate or fusiform, eight-spored, evanescent, hyaline, long-stalked. Ascospores 5–7.5 × 4–7 μm (x̄=6.47 × 5.57 μm, n=90), limoniform to broadly limoniform, olivaceous to brown, usually biapiculate at both ends, bilaterally flattened, with an apical germ pore. Asexual morph: Not observed.
Culture characteristics – Colonies on PDA attaining 30–40 mm diam after 15 d, felty, margin entire, white to black, forming dense and pale mouse grey to mouse grey ascomata. Reverse brown to black.
Material examined – China, Yunnan Province, Honghe Menglong Village, on healthy leaves of Mangifera indica, (102° 50′ 11″ E, 23° 41′ 01″ N, 500 m), 24 July 2019, E.F. Yang, EFA (MHZU 23-0263, holotype), ex- type KUNCC 22-10749; ibid. EFB, living culture, KUNCC 22-10757.
GenBank numbers – KUNCC 22-10749 = LSU: PQ014642, ITS: PQ014644, rpb2: PP766708, tub2: PP766710; KUNCC 22-10757 = LSU: PQ014643, ITS: PQ014645, rpb2: PP766709, tub2: PP766711.
Notes – Collariella hongheensis is phylogenetically closely related to C. pachypodioides (CBS 164.52, type), C. carteri (CBS 128.85, type) and C. capillicompacta (IRAN 3496C, type) (Fig. 2). Based on the sequence comparisons, Collariella hongheensis (KUNCC 22-10749 holotype) is different from C. pachypodioides (CBS 164.52 Type) in 0.53% (3/563 bp) of ITS, 0.22% (2/892 bp) of LSU, 2.23% (19/852 bp) of rpb2 and 3.29% (22/669 bp) of tub2; different from C. carteri (CBS 128.85 Type) in 0.36% (2/562 bp) of ITS, 0% (0/561 bp) of LSU, 1.92% (10/522 bp) of rpb2 and 4.20% (28/667 bp) of tub2; different from C. capillicompacta (IRAN 3496C Type) in 2.29% (11/481 bp) of RPB2 and 3.94% (21/533 bp) of tub2. Collariella hongheensis differs from C. pachypodioides by the latter having elongated ovate ascomata and only produces spirally coiled terminal hairs (Greathouse and Ames 1945; Wang et al. 2022a, b). Collariella hongheensis differs from C. carteri by the latter having short and seta-like terminal ascomatal hairs, smaller hyaline asci (30–63.5×5–13 μm vs. 17–26×8.5–11.5 μm), and ascospores limoniform, olivaceous when mature (Wang et al. 2016). Collariella hongheensis differs from C. capillicompacta by the latter having high-density and very compacted terminal hairs, significantly smaller hyaline asci (30–63.5×5–13 μm vs 21–28×10–11 μm), and smaller ascospores (5–7.5×4–7 μm vs. 5.2–6.2×4.2–5.2 μm) (Aghyl et al. 2020). Based on the phylogenetic analyses and morphological characteristics, our species is a distinct new species. In addition, in the previous study, the hamathecium of Collariella species was not observed and described. Therefore, this is the first observation of hamathecium in Collariella. Meanwhile, Chaetomiaceae species are a dominant group of endophytic fungi in mango leaves in Yunnan, China; they can also fight against plant fungal or bacterial pathogens (Yang et al. 2023a, b, 2024). Our new species was also isolated from living leaves of mangoes in Yunnan, and it might have potential antagonistic effects. Pathogen antagonistic testing needs to be conducted in the future to confirm its ability to control pathogens.
Figure 1 – Collariella hongheensis (KUNCC 22-10749 ex-type). a, b Colony characteristics on PDA (60 days old culture). c, d, f Ascomata. e Ascomatal hairs. g Masses of ascospores. h, j–m Asci. i Hamathecium. n, o Ascospores. Scale bars: d–g=200 μm; h=50 μm; i, m=30 μm; j–l, n, o=20 μm (h–m, n treated with Melzer’s reagent)
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, ITS, rpb2 and tub sequences data. Related sequences were obtained from Wang et al. (2016, 2022a, b). Twenty-seven strains are included in the combined sequence analysis, which comprises 2626 characters with gaps. Chaetomium globosum (CBS 148.51) and C. globosum (CBS 160.62) were used as the outgroup taxa. The tree topology of the ML analysis was similar to the BYPP. The best-scoring RAxML tree with a final likelihood value of − 9562.850095 is presented. The matrix had 647 distinct alignment patterns, with 17.07% of undetermined characters or gaps. Estimated base frequencies were as follows; A=0.226172, C=0.289966, G=0.278318, T=0.205544; substitution rates AC=0.911184, AG=2.964801, AT=1.311409, CG=1.266535, CT=6.151905, GT=1.000000; proportion of invariable sites I=0.558684; gamma distribution shape parameter α=1.168086. Bootstrap support values for ML equal to or greater than 60% and BYPP equal to or greater than 0.90 are given above the nodes. Newly generated sequences are in red. Type strains denoted by bold