Nothoseiridium podocarpi Crous, sp. nov.
MycoBank number: MB 835397; Index Fungorum number: IF 835397; Facesoffungi number: FoF;
Etymology. Name refers to the host genus Podocarpus from which it was isolated.
Associated with brown leaf spots. Conidiomata (on Podocarpus leaves and on SNA), black, round, flattened, acervular, 300– 400 μm diam; wall of several layers of brown textura epidermoidea, splitting open all along outer margin, appearing saucer-shaped on leaf. Conidiophores reduced to conidiogenous cells, arising from basal layers of stroma, hyaline, smooth, subcylindrical to ampulliform, annellidic, 5 –10 2.5 – 3 μm. Conidia fusoid, slightly curved, smooth-walled, guttulate, pale brown, unequally 4-euseptate; basal cell obconic with truncate hilum, hyaline; median cells pale brown; apical cell obtuse, hyaline. Apical cell 2.5 – 4 μm long; second cell 2.5 – 4 μm long; third cell 4 – 5 μm long; fourth cell 12 –14 μm long; basal cell 3 – 4 μm long; conidia (22 –)24 – 25(– 27) (2.5 –)3 μm; apical appendage ﬁliform, flexuous, unbranched, excentric, 7–10 μm long; basal appendage ﬁliform, flexuous, unbranched, excentric, 6 –7 μm long.
Culture characteristics — Colonies spreading, with moderate aerial mycelium and smooth, lobate margin, covering dish after 2 wk at 25 °C. On MEA surface smoke grey, reverse olivaceous grey. On PDA surface and reverse olivaceous grey. On OA surface pale olivaceous grey.
Typus. SOUTH AFRICA, Western Cape Province, Knysna, on leaf spots of Podocarpus latifolius (Podocarpaceae), Nov. 2018, M.J. Wingfield, HPC 2710 (holotype CBS H-24362, culture ex-type CPC 36967 = CBS 146690; ITS, LSU, rpb2, tef1 and tub2 sequences GenBank MT373363.1, MT373346.1, MT375099.1, MT375109.1 and MT375119.1).
Notes — Seimatosporium and allied genera have recently been revised (Bonthond et al. 2018, Liu et al. 2019), with 23 genera being accepted in Sporocadaceae. Nothoseiridium podocarpi is allied to Seiridium (5-septate, appendaged conidia) and Nonappendiculata (3-septate, non-appendaged conidia), but is distinct in having 4-septate, fusoid conidia with unbranched, excentric apical and basal appendages. Nothoseiridium is further characterised by forming submerged acervuli that break through the epidermis with a saucer-like appearance, being associated with prominent leaf spots. It is not possible to distinguish Nothoseiridium from Seiridium based on LSU sequence data.
Based on a megablast search of NCBIs GenBank nucleotide database, the closest hits using the ITS sequence had highest similarity to Seimatosporium lichenicola (as Discostroma fuscellum; strain GSAA-0182, GenBank JF320818.1; Identities = 542/571 (95 %), 7 gaps (1 %)), Sporocadus rosarum (as Seimatosporium pseudorosarum; strain MFLUCC 14-0466, GenBank KT284775.1; Identities = 561/592 (95 %), 4 gaps (0 %)), Seimatosporium lichenicola (strain CBS 160.25, GenBank MH854829.1; Identities = 561/592 (95 %), 6 gaps (1 %)) and Millesimomyces rhoicissi (strain CPC 35297, GenBank NR_166350.1; Identities = 566/598 (95 %), 12 gaps (2 %)). Closest hits using the LSU sequence are Seiridium unicorne (strain CBS 320.51, GenBank MH868398.1; Identities = 870/ 870 (100 %), no gaps), Seiridium pseudocardinale (strain CBS 122613, GenBank MH554206.1; Identities = 834/834 (100 %), no gaps), and Seiridium phylicae (strain CPC 19962, GenBank NG_042759.1; Identities = 870/871 (99 %), 1 gap (0 %)). Closest hits using the rpb2 sequence had highest similarity to Seiridium cardinale (strain CPC 23791, GenBank LT853119.1; Identities = 721/838 (86 %), no gaps), Seiridium unicorne (strain CBS 143873, GenBank MK058478.1; Identities = 636/741 (86 %), no gaps), and Seiridium aquaticum (voucher MFLU 18-1627, GenBank MN156531.1; Identities = 642/748 (86 %), no gaps). Closest hits using the tef1 sequence had highest similarity to Seiridium marginatum (strain CBS 140403, GenBank LT853199.1; Identities = 344/417 (82 %), 30 gaps (7 %)), Seiridium papillatum (strain CBS 340.97, GenBank LT853200.1; Identities = 332/404 (82 %), 22 gaps (5 %)), and Seiridium podocarpi (strain CBS 137995, GenBank LT853198.1; Identities = 331/403 (82 %), 31 gaps (7 %)). Closest hits using the tub2 sequence had highest similarity to Seiridium cupressi (strain CBS 224.55, GenBank LT853230.1; Identities = 652/791 (82 %), 46 gaps (5 %)), Seiridium papillatum (strain CBS 340.97, GenBank LT853250.1; Identities = 636/771 (82 %), 31 gaps (4 %)), and Seiridium podocarpi (strain CBS 137995, GenBank LT853248.1; Identities = 638/777 (82 %), 39 gaps (5 %)).