Xiuguozhangia broussonetiae Gomdola, Jayaward. & K. D. Hyde 2024, sp. nov.

Xiuguozhangia broussonetiae Gomdola, Jayaward. & K. D. Hyde sp. nov. Fig. 3 Holotype. MFLU 24-0227. Etymology. The specific epithet refers to the host genus, Broussonetia, from which the species was isolated. Description. Saprobic on decaying stems of Broussonetia papyrifera. Sexual morph not observed. Asexual morph on substrate. Hyphomycetous. Colonies on the substrate effuse, hairy, olivaceous to dark brown, appearing velvety due to numerous conidiophores. Mycelium semi-immersed or immersed, composed of septate, branched, smooth, hyaline or pale brown to brown hyphae. Conidiophores (430 –) 550–750 (– 890) µm long (x – = 681 µm, n = 10), 15–24 (– 34) µm wide (x – = 21.8 µm, n = 10) at the base, 11–14 (– 16) µm wide (x – = 12.3 µm, n = 10) in the middle, 7–10 µm (– 12) wide (x – = 7.8 µm, n = 10) at the apex, rarely branched, macronematous, mononematous, differentiated, smooth, thick-walled, erect, straight or flexuous, brown to dark brown, wider at the base and ocasionally conical at the apex, comprising 12–17 septa. Conidiogenous cells 5–12 µm long × 4–9 µm wide (x – = 7.4 × 6.2 µm, n = 10), holoblastic, enteroblastic, integrated, smooth-walled, ovoid to ampulliform, hyaline or brown to dark brown, occurring terminally or intercalary on conidiophores, with up to four successive percurrent proliferations, with new conidiogenous cells developing on subtending cells. Conidia 25–40 µm long × 30–60 µm wide (x – = 35 × 47 µm, n = 30), width measured between the two extremities of the apices, solitary, dictyospored and cheirospored, fan-shaped to cheiroid, lenticular in edge view, occasionally apically 2–3 - lobed, dark brown to olivaceous brown, dictyoseptate, with up to 15 columns of cells radiating from a protuberant basal cell 2–3 µm wide, septa obscured by dark pigmentation, and with 1–3 apical appendages (rarely without appendages). Apical appendages (2 –) 6–16 (– 20) µm long (x – = 10.9 µm, n = 10), 4–5 µm wide (x – = 4.4 µm, n = 10) at the base, 4–5 µm wide (x – = 4.1 µm, n = 10) at the apex, mostly short and untapered, sometimes long and tapering, arising from the sides of the outermost rows of cells of the conidium, pale brown to brown, becoming hyaline and rounded at the tips, and consisting of 1–5 septa. Culture characteristics. On PDA, colony circular with lobate to crenated margin, reaching 25 mm diam. after 28 days incubated at 25 ° C, greyish white to olivaceous brown from center to edge, fluffy, raised to convex, penetrating the media and displaying a dark brown colour around the media. Material examined. Thailand • Chiang Rai Province, Mae Fah Luang University Botanical Garden, on decaying stems of Broussonetia papyrifera (Moraceae), 19 May 2023, D. Gomdola, F 2 - A (MFLU 24-0227, holotype), ex-type MFLUCC 24-0258. Additional material examined. Thailand • Chiang Rai Province, Mae Fah Luang University Botanical Garden, on decaying stems of Broussonetia papyrifera (Moraceae), 19 May 2023, D. Gomdola, F 2 - B (MFLU 24-0228), living culture MFLUCC 24-0259. GenBank accession numbers. MFLUCC 24-0258; ITS = PQ 137417, LSU = PQ 137419, SSU = PQ 137421, RPB 2 = PQ 488459 and TEF 1 = PQ 488461; MFLUCC 24-0259; ITS = PQ 137418, LSU = PQ 137420, SSU = PQ 137422 and RPB 2 = PQ 488460. Notes. Our two isolates (MFLUCC 24-0258 and MFLUCC 24-0259) group together with 100 % ML and 1.00 PP support, and this subclade is sister to Pseudoberkleasmium species with 100 % ML and 1.00 PP support (Figs 1, 2). A close comparison of the morphological characters across the existing Xiuguozhangia species is collated and presented in Table 3 to support the establishment of the new species, X. broussonetiae. A summary of the main findings from the morphological assessment is presented below: The conidiophores of our species, Xiuguozhangia broussonetiae, are longer than all other Xiuguozhangia taxa (up to 890 μm long), comprising numerous septa (up to 17). Furthermore, conidiophores of other Xiuguozhangia species are unbranched, while those of X. broussonetiae are sometimes branched (Fig. 3 E). The conidia of Xiuguozhangia broussonetiae (Figs 3 J – O, Q, R) consist of up to 15 columns of cells radiating from a protuberant basal cell that is smaller (2–3 μm wide) compared to those of other species. The appendages of X. broussonetiae are mostly untapered (Figs 3 N, 3 P – R) and sometimes taper towards the tips (Fig. 3 B), whereas all other Xiuguozhangia species have only tapering appendages. Xiuguozhangia broussonetiae differs from all extant species but has a close morphological overlap with X. rosae. However, the primary feature that demarcates X. broussonetiae from X. rosae is the number and features of the apical appendages. Up to three appendages were observed in X. broussonetiae (sometimes seen without appendage), while X. rosae has two appendages. In addition, the appendages of X. broussonetiae are 1–5 - septate, while those of X. rosae display one to two septa. Xiuguozhangia broussonetiae has percurrently proliferating, enteroblastic conidiogenous cells that sometimes produce new conidiogenous cells on subtending cells (Fig. 3 D – I). This feature has not been observed in other species of the genus. Based on these morphological differences, we conclude that our taxon is distinct from the existing Xiuguozhangia species.