Juncomyces californiensis Crous, sp. nov.
MycoBank number: MB 835405; Index Fungorum number: IF 835405; Facesoffungi number: FoF 11160;
Etymology. Name refers to the state of California, where it was collected.
Mycelium consisting of brown, smooth to warty, septate, branch- ed, 2 – 3 µm diam hyphae. Conidiophores solitary, subcylindrical, mostly unbranched, erect, 80 –180 × 5 –7 µm, thick-walled, brown, verruculose, warty, multiseptate, rarely forming from a brown stroma, up to 120 µm diam, with 1– 3 fasciculate conidiophores, up to 60 µm tall. Conidiogenous cells integrated, terminal, straight to geniculate-sinuous, 35 – 60 × 5 –7 µm; proliferating sympodially with several apical loci, flattened, thickened, darkened, and refractive, 4.5 – 5.5 µm diam. Conidia solitary, acicular to slightly obclavate, mostly thick-walled, verruculose, guttulate, apex subobtuse, base truncate, 4.5 – 5 µm diam, thickened, darkened and refractive, 3(– 6)-septate, (65 –)70 – 85(– 90) × (7–)8(– 9) µm.
In vivo: Conidiophores on culms erect, solitary, rarely in fascicles of 2 – 3, straight, 2 – 6-septate, subcylindrical, rejuvenating percurrently, 50 –110 × 5 –7 µm, arising from immersed, brown, weakly developed stroma, 20–40 µm diam. Conidiogenous cells integrated, terminal and intercalary, medium brown, smooth, 10 – 45 × 5 – 6 µm with one to several loci, round, thickened, refractive, 3 – 4 µm diam. Conidia solitary, arranged in clusters on conidiophores, obclavate, slightly curved to straight, apex subobtuse, base truncate, 3 –7-septate, at times constricted at some of the septa, thick-walled, medium brown, verruculose, hilum thickened, darkened, refractive, 4 – 5 µm diam, (45 –)55 –70(–75) × (6 –)7(– 8) µm.
Culture characteristics — Colonies erumpent, spreading, with sparse aerial mycelium and smooth, feathery, even margin, reaching 12 mm diam after 2 wk at 25 °C. On MEA, PDA and OA surface olivaceous grey, reverse iron-grey.
Typus. USA, California, UC Davis, on leaves of Juncus effusus (Juncaceae), 3 Apr. 2019, P.W. Crous, HPC 2894 (holotype CBS H-24363, culture ex-type CPC 37989 = CBS 146682; ITS and LSU sequences GenBank MT373368.1 and MT373351.1).
Additional material examined. USA, California, UC Davis, on leaves of J. effusus, 3 Apr. 2019, P.W. Crous, HPC 2895, culture CPC 37993 = CBS 146631; ITS, LSU and rpb2 sequences GenBank MT373369.1, MT373352.1 and MT375101.1.
Notes — Juncomyces is closely related to Graminopassalora, which was introduced to accommodate Passalora graminis, a widespread pathogen occurring on a broad range of grass (Poaceae) hosts (Videira et al. 2017). Juncomyces differs from Graminopassalora by chiefly having solitary conidiophores (rarely fascicles of 2 – 3), and multiseptate, obclavate conidia.
Based on a megablast search of NCBIs GenBank nucleotide database, the closest hits using the ITS sequence of CPC 37989 had highest similarity to Graminopassalora graminis (strain CBS 113303, GenBank GU214666.1; Identities = 474/538 (88 %), 18 gaps (3 %)), Mycosphaerella fimbriata (strain CBS 120736, GenBank NR_137553.1; Identities = 465/526 (88 %), 16 gaps (3 %)), and Zasmidium corymbiae (strain CBS 145049, GenBank MK047423.1; Identities = 476/542 (88 %), 21 gaps (3 %)). The ITS sequences of CPC 37989 and 37993 are 100 % (528/528 bp) identical. Closest hits using the LSU sequence of CPC 37989 are Xenosonderhenia eucalypti (strain CBS 138858, GenBank NG_058120.1; Identities = 773/799 (97 %), 2 gaps (0 %)), Ramularia lethalis (strain CPC 25910, GenBank KX287174.1; Identities = 780/808 (97 %), no gaps), and Ramularia acris (strain CBS 109794, GenBank KX287010.1; Identities = 780/808 (97 %), no gaps). The LSU sequences of CPC 37989 and 37993 are 100 % (808/808 bp) identical. Closest hits using the rpb2 sequence of CPC 37993 had highest similarity to Ramularia gei (strain CBS 344.49, GenBank KX288570.1; Identities = 637/840 (76 %), 14 gaps (1 %)), Ramularia unterseheri (strain CBS 124884, GenBank KP894709.1; Identities = 636/849 (75 %), 8 gaps (0 %)), and Ramularia heraclei (strain CPC 11507, GenBank KX288584.1; Identities = 634/848 (75 %), 6 gaps (0 %)).