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Based on the morphological and phylogenetic analyses, we introduce a new species, Rhexoacrodictys melanospora, collected on decaying wood from terrestrial habitats in Yunnan, China. Phylogenetic analyses based on the combination of four loci (LSU, SSU, ITS and RPB2 data) demonstrated high support for establishing a new species within Rhexoacrodictys. The morphological characteristics of R. melanospora and the differences compared with the members of Rhexoacrodictys are also given in detail herein.

Rhexoacrodictys melanospora S.X. Bao, R.J. Xu & Q. Zhao, sp. nov. Index Fungorum Number: IF559983. Facesoffungi Number: FoF 12898; Fig. 2. Etymology: The specific epithet ‘ melanospora ’ refers to the dark conidia of the fungus Saprobic on decaying woods in terrestrial habitat. Sexual morph: Undetermined. Asexual morph: Conidiophores 19–60 × 3–5 μm (Q = 40 × 4 μm, n = 20), macronematous, mononematous, erect, straight or somewhat fexuous, pale brown to brown, cylindrical, thick-walled, smooth, 2–4 septate. Conidiogenous cells 2–6 × 3–4 μm (Q = 4 × 3.5 μm, n = 10), monoblastic, integrated, terminal, pale brown, cylindrical, with 1–3 pale brown percurrent extensions. Conidia 16–32 × 12–21 μm (Q = 23 × 16 μm, n = 40), solitary, acrogenous, ellipsoidal to obovoid or somewhat subglobose, muriform, with 2–5 transverse and several oblique septa, pale brown when immature, becoming dark brown at maturity, thick and smooth-walled. Culture characteristics: Colonies on PDA, reaching 4 cm diam. after 15 days at room temperature (25 ˚C), colonies irregular, surface taupe, mycelium dense, and reverse blackish. Material examined:— CHINA. Yunnan Province, Fugong County, decayed wood in terrestrial habitats, 13 May 2021, Song Wang, GLG41-1 (HKAS 124580, holotype), ex-type KUNCC 22-12406; China, Derung-Nu Autonomous County of Gongshan, 15 May 2021, Song Wang, GLG41-2 (HKAS 124581, paratype), ex-paratype KUNCC 22- 12411. Notes: Rhexoacrodictys melanospora is easily distinguished by its macronematous, conidiophores, and conidia ellipsoidal, 2–5 transverse, and several oblique septate. R. melanospora clustered with R. erect and R. fimicola with strong bootstrap support (100% ML/1.00 BI). However, R. melanospora has shorter conidiophores than R. fimicola (19–60 μm vs. up to 75 μm) (Baker et al. 2002), R. erect has numerous irregular septa, and R. melanospora just has 2–5 transverse and several oblique septa (Baker et al. 2002, Zhao et al. 2011). Among the four species of Rhexoacrodictys (Index Fungorum 2023), R. broussonetiae and R. fuliginosa lack DNA sequences. Although their molecular data deficiency, R. melanospora clearly differs from R. broussonetiae and R. fuliginosa by its shorter conidiophores, 19–60 μm (vs. 70–90 μm in R. broussonetiae, and vs. up to 85 μm in R. fuliginosa) and longer conidia, 16–32 μm (vs. 17–28μm in R. broussonetiae, and vs. 17–27 μm in R. fuliginosa) (Baker et al. 2002, Zhao et al. 2011, Xiao et al. 2018). A morphological comparison of Rhexoacrodictys species is summarized in Table 2 and a photo plate of R. melanospora is in Fig. 2.

During investigations into freshwater fungi from the Great Mekong Subregion, four Distoseptispora taxa were collected from China and Thailand. Based on morphological characteristics, and phylogenetic analyses of combined LSU, ITS, SSU, TEF1-α, and RPB2 sequence data, two new species Distoseptispora bangkokensis and D. lancangjiangensis are introduced, and two known species D. clematidis and D. thysanolaenae were first reported in freshwater habitat. Illustrations and descriptions of these taxa are provided, along with comparisons with extant taxa in the genus.

Bamboo is a widespread plant with medicinal value. During our taxonomic study on medicinal plants, three collections of Distoseptispora were made from China and Thailand. Phylogenetic analyses of combined LSU, ITS and RPB2 sequence data showed that two collections represented a new species, phylogenetically distinct from other described species in Distoseptispora. This new species has macronematous, mononematous conidiophores, polyblastic or monoblastic conidiogenous cells and acrogenous, solitary, straight, obclavate, multi-septate, thick-walled conidia. Distoseptispora bambusae sp. nov. is introduced with illustrations and a comprehensive description. The third collection on dead wood from Thailand was identified as D. tectona with newly-generated molecular data for this taxon.

Decaying bamboo in freshwater is a unique eco-environment for fungi. Three new Distoseptispora (Distoseptisporaceae) species, D. meilingensis, D. yongxiuensis and D. yunjushanensis from submerged decaying bamboo culms in Jiangxi Province, China, were discovered, based on phylogenetic analyses and morphological characters. The combined data of ITS-LSU-SSU-Tef1 sequences were used to infer the phylogenetic relationship between D. meilingensis, D. yongxiuensis, D. yunjushanensis and related species. Both molecular analyses and morphological data supported D. meilingensis, D. yongxiuensis and D. yunjushanensis as three independent taxa.

In this study, five aquatic hyphomycetous taxa were collected and isolated from submerged wood in Lancang River located in the northwestern Yunnan Province of China. Phylogenetic analyses based on combined LSU, ITS, tef1α and rpb2 sequence matrix indicated that those five taxa belonging to Distoseptispora (Distoseptisporaceae), and they can be recognized as four species which two are introduced as new species (Distoseptispora euseptatensis and D. yunnanensis) and two are identified as D. aquatica and D. tectonae. Two isolates of the new species Distoseptispora euseptatensis formed a distinct clade among Distoseptispora species (basal to D. suoluoensis and D. bambusae) with good support (ML 100%, MP 100%, BI 1.00 PP). Distoseptispora yunnanensis clustered together with D. euseptatensis, but they are difference in the size of conidiophore and conidia. Corresponding illustrations, descriptions and phylogenetic evidences are provided to justify the placement of our newly collected Distoseptispora taxa.

Distoseptispora yunnanensis W.L. Li, H.Y. Su & Jian K. Liu, sp. nov. FIGURE 3 Index Fungorum number: 557968; Facesoffungi number: FoF 09451. Etymology:— The specific epithet ‘yunnanensis’ refers to the locality where the fungus was collected, Yunnan Province, China. Holotype:— MFLU 20–0625 Saprobic on decaying submerged wood in freshwater habitats. Sexual morph: undetermined. Asexual morph: Colonies effuse, olivaceous or dark brown, hairy or velvety. Mycelium mostly immersed, consisting of unbranched, septate, smooth, hyaline to pale brown hyphae. Conidiophores 131–175 μm long (x = 153 μm, SD = 22, n = 30), 6–7 μm wide (x = 6.5 μm, SD = 0.6, n = 30), macronematous, mononematous, solitary or in groups of a few, erect, straight or flexuous, 6–10-septate, unbranched, cylindrical, smooth, brown to dark brown, round at the apex, Conidiogenous cells monoblastic, holoblastic, integrated, terminal, determinate or indeterminate, brown to olivaceous, cylindrical. Conidia 58–108 μm long (x = 83 μm, SD = 25, n = 30), 8–10 μm wide (x = 9 μm, SD = 0.9, n = 30), acrogenous, solitary, obclavate, rostrate, straight or slightly curved, 6–10-euseptate, slightly constricted at septa, mid olivaceous to brown, becoming paler towards the apex, truncate with a darkened scar at base, smooth-walled. Material examined:— CHINA, Yunnan Province, Lancang River, saprobic on submerged decaying wood, June 2018, W.L. Li, 2L H 1–5–1 (MFLU 20–0625, holotype), ex-type living culture MFLUCC 20–0153. Cultural characteristics:— Conidia germinating on PDA within 24 h and germ tubes produced from the apex. Colonies on PDA reaching 5–10 mm diam. at 14 days at 25 °C, in natural light, circular, with fluffy, dense, dark olivaceous mycelium on surface with entire margin; in reverse dark green to black. Notes:— The phylogenetic result (FIG. 1) showed that our isolate (MFLUCC 20–0153) clustered together with Distoseptispora bambusae, D. euseptata and D. suoluoensis, forming a distinct clade with high supported bootstrap (100% ML, 100% MP, 1.00 PP). Distoseptispora yunnanensis is phylogenetically close to D. euseptata. However, Distoseptispora yunnanensis differs from D. euseptata in having much larger conidiophores (131–175 μm vs. 19– 28 μm) and conidia (58–108 μm vs. 37–54 μm), as well as more conidial septate (6–10 vs. 4–7). Distoseptispora yunnanensis can be easily distinguished from D. bambusae by its rostrate conidia and sometimes percurrently elongating conidiogenous cells. In addition, Distoseptispora yunnanensis has larger conidiospores (131–175 μm vs. 40–96 μm) and conidia (58–108 μm vs. 45–74 μm) (Sun et al. 2020). The conidiogenous cells of D. suoluoensis are lageniform or cylindrical with truncate apex, while they are cylindrical with rounded apex in D. yunnanensis (Yang et al. 2017)., Published as part of Li, Wen-Li, Liu, Zuo-Peng, Zhang, Tian, Dissanayake, Asha J., Luo, Zong-Long, Su, Hong- Yan & Liu, Jian-Kui, 2021, Additions to Distoseptispora (Distoseptisporaceae) associated with submerged decaying wood in China, pp. 75-86 in Phytotaxa 520 (1) on pages 80-83, DOI: 10.11646/phytotaxa.520.1.5, http://zenodo.org/record/5502782, {"references":["Sun, Y. R, Goonasekara, I. D., Thambugala, K. M., Jayawardena, R. S., Wang, Y. & Hyde, K. D. (2020) Distoseptispora bambusae sp. nov. (Distoseptisporaceae) on bamboo from China and Thailand. Biodiversity Data Journal 8: e 53678. https: // doi. org / 10.3897 / BDJ. 8. e 53678","Yang, J., Maharachchikumbura, S. S. N., Liu, J. K., Hyde, K. D., Gareth Jones, E. B., Al-Sadi, A. M. & Liu, Z. Y. (2017) Pseudostanjehughesia aquitropica gen. et sp. nov. and Sporidesmium sensu lato species from freshwater habitats. Mycological Progress 17 (5): 591 - 616 http: // dx. doi. org / 10.1007 / s 11557 - 017 - 1339 - 4"]}