Paradissoconium narthecii Crous & Boers, sp. nov.
MycoBank number: MB 841795; Index Fungorum number: IF 841795; Facesoffungi number: FoF 15680;
Etymology. Name refers to the host genus Narthecium from which it was isolated.
Ascospores could not be linked to specific ascomata on host tissue, as several taxa were involved, including species with pseudothecia and thyrothecia. Ascospores smooth-walled, fusoid-ellipsoid, widest just above septum, germinating with flex- uous germ tubes from both polar ends, spore becoming brown and verruculose, 6 μm diam, constricted at septum, not distort- ed. Mycelium consisting of hyaline, smooth, branched, septate, 2 − 3 μm diam hyphae. Conidiophores solitary, unbranched, erect, subcylindrical to subulate, with truncate apex, straight to gently curved, smooth, pale brown, 0−2-septate, 15−100 ×
3.5−4.5 μm. Conidiogenous cells terminal, integrated, 15 − 45 × 3 − 4 μm, loci slightly darkened, 1− 2 μm diam, cicatrized, at times subdenticulate, proliferating sympodially, and rejuvenating percurrently. Primary conidia (12 −)14 −16(−18) × (5 −)6 −7 μm, solitary, straight, constricted at median septum, smooth, hyaline, ellipsoid, apex obtuse, base obconically truncate, hilum pro- nounced, darkened, 2 − 2.5 μm diam. Secondary conidia 6 − 9 × 5 − 6 μm, adjacent to primary conidia, hyaline, smooth, aseptate, ellipsoid, tapering to truncate hilum, 2 – 2.5 μm; anastomosing with primary conidia after active discharge.
Culture characteristics — Colonies erumpent, spreading, with moderate aerial mycelium and feathery, lobate margin, reaching 6 mm diam after 7 d at 25 °C. On MEA, PDA and OA surface and reverse olivaceous grey.
Typus. NETHERLANDS, Drenthe Province, Dwingelderveld National Park, 52.829188, 6.432495, on dead leaves of Narthecium ossifragum (Narthe ciaceae), 4 July 2021, J. Boers, HPC 3653 (holotype CBS H-24891, cultures ex-type CPC 41970, 41971 = CBS 148449, ITS, LSU, actA and rpb1 sequences GenBank OK664712.1, OK663751.1, OK651125.1 and OK651151.1).
Additional materials examined. NETHERLANDS, Drenthe Province, Dwingel- derveld National Park, 52.829188, 6.432495, on dead leaves of N. ossifragum, 4 July 2021, J. Boers, HPC 3653, single ascospore cultures CPC 41976, 41977.
Notes — The distinction between Dissoconium and Uwe braunia was discussed by Li et al. (2012). Both genera have solitary conidiophores with actively discharging aseptate sec- ondary and 1-septate primary conidia that anastomose upon discharge onto the agar surface. Uwebraunia and Dissoconium have pseudothecial sexual morphs (Crous et al. 2004, Hyde et al. 2020). Paradissoconium has a typical dissoconium-like asexual morph that develops in culture, and is morphologically similar to Dissoconium s.str. Thus far Paradissoconium is mono- typic but appears commonly on dead leaves of Narthecium ossifragum, where it is associated with thyrothecia. Although we tried on several locations to link the asexual and sexual morph, all attempts were unsuccessful, as too many diverse sexual morphs were involved. Paradissoconium is located basal in Dissoconiaceae.
Based on a megablast search of NCBIs GenBank nucleotide database, the closest hits using the ITS sequence had highest similarity to ‘Dissoconium sp. GS-2011’ (strain MYQWGNL19, GenBank JF701607.1; Identities = 483 / 491 (98 %), four gaps (0 %)), Ramichloridium punctatum (strain NTOU 4892, GenBank MK448255.1; Identities = 465/509 (91 %), 14 gaps (2 %)), and Dissoconium proteae (strain CBS 122900, GenBank NR_156213.1; Identities = 469 /514 (91 %), 17 gaps (3 %)). Closest hits using the LSU sequence are Ramichloridium eu cleae (strain CBS 138000, GenBank NG_058086.1; Identities = 814/828 (98 %), two gaps (0 %)), Ramichloridium indicum (strain CBS 171.96, GenBank EU041856.1; Identities = 811/827 (98 %), no gaps), and Ramichloridium apiculatum (strain CPC 12310, GenBank GU214687.1; Identities = 809/828 (98 %), two gaps (0 %)). Closest hits using the actA sequence had highest similarity to Uwebraunia communis (as Mycosphaerella communis; strain X1023, GenBank EU514299.1; Identities = 490/569 (86 %), 29 gaps (5 %)), Pseudophaeophleospora phormii (strain CBS 144606, GenBank MK442643.1; Identities = 427/480 (89 %), 16 gaps (3 %)), and Zasmidium com mune (strain CBS 142528, GenBank KY979857.1; Identities = 366 /392 (93 %), one gap (0 %)). Distant hits obtained using the rpb1 sequence had highest similarity to Nothophaeocryp topus gaeumannii (strain CBS 267.37, GenBank GU357770.1; Identities = 513 /723 (71 %), 34 gaps (4 %)), Zymoseptoria tritici (strain ST99CH_3D1, GenBank LT854276.1; Identities = 493 /717 (69 %), 27 gaps (3 %)), and Rasutoria tsugae (strain ratstk, GenBank GU371809.1; Identities = 489/720 (68 %), 31 gaps (4 %)).