Dicephalospora xishuangbannaensis L. Luo & Q.Zhao

Luo, L., Wei, D. P., Zhao, Q. & Chethana, K. W. Thilini, 2024, Unveiling the Diversity: A Novel Species of Dicephalospora (Helotiaceae, Helotiales) Discovered in China, Phytotaxa 652 (1), pp. 59-68 : 64-65

Dicephalospora xishuangbannaensis L. Luo & Q.Zhao , sp. nov.

Index Fungorum number: IF 901537; Faces of fungi number: FoF 15271; Figure 2

Etymology: the epithet refers to the collection site of the type specimen.

Holotype: HKAS 131164

Saprobic on dead twigs. Sexual morph: Apothecia discoid, 0.9–1.9 mm diameter when dry, scattered to gregarious, centrally stipitate, superficial, yellow to orange when fresh and dry. Stipe 0.9–1.3 mm high, orange at the base. Receptacle surface orange and cupulate with smooth and orange to dark orange margins. Disc slightly sunken and orange. Ectal excipulum 25–53 µm (x̄ = 41 µm, n = 60), multi-layered, comprised of hyaline to yellow cells of textura oblita to textura angularis. Medullary excipulum 21–45 µm (x̄ = 31 µm, n = 60), composed of thin-walled, hyaline to yellowish, gelatinized cells of textura porrecta. Hymenium 84–111 µm (x̄ = 99 µm, n = 60) thick, hyaline to yellowish, with asci and paraphyses immersed in the gelatinized substances. Paraphyses 1.1–2.1 µm wide (x̄ = 1.6 µm, n = 60), filiform, aseptate, unbranched, slightly enlarger toward the round apices. Asci 106–134 × 8.2–12.2 µm (x̄ = 120 × 10 µm, n = 50), unitunicate, eight-spored, cylindrical to clavate, with a non-amyloid (J-) apical apparatus. Ascospore s 19–27 × 4–6 µm (x̄ = 23.1 × 4.9 µm, n = 60), uniseriate to biseriate, fusiform, guttulate, either narrow, tapered or rounded ends, capped with a small gelatinous sheath at both ends. Asexual morph: undetermined.

Material examined: China, Yunnan Province, Xishuangbanna , on a dead twig of an unidentified tree, alt. 499m, 1 September 2022, Le Luo, ly638 ( HKAS 131164 , holotype) ; ibid., alt. 528m, 1 September 2022, Le Luo, ly38 ( HKAS 131157 , paratype) .

Notes: Our specimens HKAS 131164 and HKAS 131157 grouped as a distinct clade, closely related to Dicephalospora sessilis ( MFLU 181823) and D. dentata (3093) by 94% MLBS and 0.99 BIPP ( Fig. 1 ). The newly described species D. xishuangbannaensis has an orange receptacle surface and orange to dark orange margins, while D. sessilis has a reddish-orange receptacle surface and magenta to reddish-orange margins. Dicephalospora xishuangbannaensis has orange discs, an ectal excipulum of textura oblita to textura angularis cells, a medullary excipulum of textura porrecta cells and smaller asci (106–134 × 8.2–12.2 µm vs. 130–140 × 15–20 µm) and longer ascospores (19–27 × 4–6 µm vs. 15–20 × 5–10 µm) compared to D. sessilis , which has magenta to orange discs, an ectal excipulum of textura prismatica to intricata cells, and a medullary excipulum of textura intricata ( Ekanayaka et al. 2019). Furthermore, D. xishuangbannaensis also differs from D. dentata by the latter having smooth and dentatemargined apothecia and a slightly darker orange receptacle surface. In comparison, D. xishuangbannaensis has smaller asci (106–134 µm × 8.2–12.2 µm vs. 173–180 × 10 µm), shorter ascospores (19–27 × 4–6 µm vs. 37–45 × 4–5 µm), and non-amyloid (J-) asci compared to the amyloid (J+) asci of D. dentata . Besides, D. dentata has an ectal excipulum of textura prismatica and a medullary excipulum of textura intricata, which are different from our species ( Liu et al. 2016 b).

Furthermore, we did not include Dicephalospora pinglongshanica and D. damingshanica in our phylogenetic analyses as their molecular data are unavailable. However, our specimens morphologically differ from them. Dicephalospora xishuangbannaensis has hyaline to yellowish hymenium when dry, an orange stipe at the base, and longer asci (106–134 × 8.2–12.2 µm vs. 96–115 × 10–14 µm). In contrast, D. pinglongshanica has brownish red hymenium when dry and dark-coloured stipe at the base. Dicephalospora xishuangbannaensis also differs from D. damingshanica in having shorter asci (106–134 × 8.2–12.2 µm vs. 165–185 × 16–20 µm) and narrower paraphyses (1.1–2.1 µm vs. 3–5.5 µm). Dicephalospora damingshanic a also differs by having an ectal excipulum of small-celled textura prismatica and a medullary excipulum of textura intricata. Additionally, the asci of our specimens have non-amyloid apical apparatus (J-), while those of D. pinglongshanica and D. damingshanic a are amyloid ( Zhuang 1999).

Figures

FIGURE 1. Phylogram of RAxML analysis based on the combined LSU and ITS sequence dataset. Bootstrap support values for maximum likelihood equal to or greater than 50%, and Bayesian posterior probability equal to or greater than 0.95 BYPP are indicated at the nodes as ML/BYPP. The generic names were denoted in the right side of tree. Type strains are in bold. The newly generated isolates are in red.

FIGURE 2. Dicephalospora xishuangbannaensis (HKAS 131164, holotype). a Fresh specimen growing on a dead wood; b Cross section of the apothecium; c–e Close-up of the ectal excipulum and medullary excipulum cells; f–g Paraphyses; h–l Immature to mature asci (l treated with Melzer’s reagent); m, n Apices of asci treated with Melzer’s reagent; o–t Ascospores. Scale bars: b = 200 µm; c = 100 µm; d, f–l = 50 µm; e, m–n = 20 µm; o–t = 10 µm.