Pseudodactylaria fusiformis Y.Z. Lu, J.Y. Zhang & Jian K. Liu, 2020

Lu, Yong-Zhong, Zhang, Jing-Yi, Lin, Chuan-Gen & Luo, Zong-Long, 2020, Pseudodactylaria fusiformis sp. nov. from freshwater habitat in China, Phytotaxa 446 (2), pp. 95-102 : 97-98

Pseudodactylaria fusiformis Y.Z. Lu, J.Y. Zhang & Jian K. Liu , sp. nov. FIGURE 2

Index Fungorum : IF 557329; Facesoffungi number: FoF 07741

Etymology: ‘ fusiformis ’ referring to the fusiform conidia of this fungus.

Saprobic on submerged decaying wood in freshwater. Sexual morph: undetermined. Asexual morph: hyphomycetous. Colonies on the substratum superficial, effuse, gregarious, white. Mycelium composed of partly immersed, partly superficial, hyaline, septate, branched hyphae. Conidiophores macronematous, mononematous, solitary, erect, unbranched, subcylindrical, straight to slightly flexuous, hyaline, 1–3-septate, 30–50 × 3.5–4.5 μm (x = 38 × 4 μm, n = 20). Conidiogenous cells holoblastic, polyblastic, integrated, terminal, sympodial, subcylindrical, straight or flexuous, hyaline, 14–28 × 3.5–4.5 μm (x = 20 × 4 μm, n = 20), apical part forming a rachis with numerous, aggregated, cylindrical denticles, 0.9–1.5 × 0.7–1.5 μm. Conidia solitary, acropleurogenous, smooth, prominently guttulate, 0–1-septate, fusiform, subtruncate at base, subobtuse at apex, hyaline, 20–25 × 3–4 μm (x = 22.5 × 3.5 μm, n = 30).

Culture characteristics: Conidia germinating on water agar and producing germ tubes within 12 hours. Colonies growing on PDA, circular, with flat surface, edge entire, reaching 12 mm in 10 days at 28 °C, greyish white.

Material examined: CHINA, Guizhou province, Zunyi city, Chishui county, Hushi town , Chishui Alsophila Natural Reserve (28°29’43”N, 106°0’24”E), on submerged decaying bamboo culms in a freshwater stream, 22 September 2019, Yong-Zhong Lu, C 1–1 ( MFLU 20–0204 , holotype; GZAAS 20–0095 , isotype) ; ex-type living culture, MFLUCC 20–0085 . Additional sequence: SSU: MT184897 , RPB2 : MT188555 , TEF1 α: MT188556 .

Notes: Morphologically, Pseudodactylaria fusiformis is similar to P. hyalotunicata and P. xanthorrhoeae in having unbranched hyaline conidiophores but can be distinguished by its conidia without a sheath ( Tsui et al. 1997; Crous et al. 2017). It is also similar to P. brevis and P. camporesiana in having hyaline, 1-septate fusiform conidia without a sheath. However, Pseudodactylaria fusiformis can be distinguished from P. brevis by its larger conidia (20–25 μm vs. 11.5–17.5 μm) and conidiophores (30–50 μm vs. 11–25 μm) ( Lin et al. 2018), and from P. camporesiana by its hyaline conidiophores while the later is brown at the base ( Hyde et al. 2020). Phylogenetically, Pseudodactylaria fusiformis shares a sister relationship to P. camporesiana with good bootstrap support (100 MLBS/100 MPBS/ 1.00 PP) ( FIGURE 1 ), and the phylogenetic analysis showed that P. fusiformis is distinct from other Pseudodactylaria species. Following the recommendations of Jeewon & Hyde (2016) for delimitation of new species, we delved into pairwise dissimilarities of DNA sequences and noted that there are 36 nucleotide differences among 527 nucleotides in the ribosomal ITS sequences (6.83% nucleotide differences), and 6 base pair differences in LSU (data did not contain a gap) between Pseudodactylaria fusiformis and P. camporesiana , which confirmed our new taxon is a novel species.

Figures

FIGURE 1. Phylogenetic tree generated from ML analysis based on combined ITS and LSU sequence data for subclass Sordariomycetidae. Bootstrap support values for maximum likelihood (ML, first set) and maximum parsimony (MP, second set) greater than 75 % and Bayesian posterior probability greater than 0.95 (PP) are indicated above the branches. Hyphen (“-”) indicates a value lower than 75% for ML and MP and a posterior probability lower than 0.95 for PP. The new isolate is in red and ex-type strains are in bold. The tree is rooted with Arthrinium arundinis (AFTOL-ID 951 and CBS 133509) (Apiosporaceae).

FIGURE 2. Pseudodactylaria fusiformis (MFLU 20–0204, holotype). a Host material. b, c Colony on decaying wood.d–f Conidiophores. g, h Conidiogenous cells with attached conidia. i Germinating conidium. j–m Conidia. n, o Colony on PDA from above and below. Scale bars: b = 100 µm, c = 50 µm, d–i = 20 µm, j–m = 10 µm.