Proliferodiscus ingens S.Bien & Damm, 2020

Bien, Steffen & Damm, Ulrike, 2020, Arboricolonus simplex gen. et sp. nov. and novelties in Cadophora, Minutiella and Proliferodiscus from Prunus wood in Germany, MycoKeys 63, pp. 119-161 : 119

Proliferodiscus ingens S.Bien & Damm sp. nov. Figures 5K , 15

Type.

Germany, Baden-Württemberg, orchard south of Oppenau, on a hill, 48°27'57.6"N, 8°09'11.0"E, from necrotic wood of Prunus avium , 24 Aug 2016, S. Bien leg., GLM-F110834 - holotype; GLMC 1751 = CBS 145519 = DSM 109148 - culture ex-type.

Etymology.

Named after the comparatively huge conidiomata (ingens Lat. = huge).

Description.

Sexual morph not observed. Asexual morph on OA. Vegetative hyphae hyaline, smooth-walled, septate, branched, 1.5-3 μm wide, lacking chlamydospores. Sporulation abundant, conidia formed in conidiomata. Conidiomata produced on OA in 2-4 wk, solitary or aggregated, subglobose, unilocular, superficial, 250-1000 μm wide, dull green to grey olivaceous, almost glabrous to completely covered with hairs, opening with an irregular rupture. Conidiophores hyaline, smooth-walled, septate, sometimes branched at the base and above, conidiogenous loci formed terminally. Conidiogenus cells enteroblastic, hyaline, smooth-walled, navicular to subulate, tapering towards apices, 8-15 × 1-2 μm; collarettes hardly visible, cylindrical, <1 μm long, opening 0.5-1 μm, periclinal thickening sometimes visible. Conidia hyaline, smooth-walled, aseptate, cylindrical to ellipsoidal, straight, with both ends rounded, 2.5-3(-3.5) × 1-1.5 μm, mean ± SD = 2.9 ± 0.2 × 1.4 ± 0.1 μm, L/W ratio = 2.1.

Culture characteristics.

Colonies on OA raised with entire to crenated margin, buff to pale olivaceous grey, white at the margin, with umber to black spots due to conidiomata, aerial mycelium sparse, white, reverse buff to cinnamon, 1-2 mm diam. in 2 wk, 2-3 mm diam. in 4 wk. Colonies on SNA flat to very low convex with entire to fimbriate margin, white, lacking aerial mycelium, reverse same colour; 1-2 mm diam. in 2 wk, 2-3 mm diam. in 4 wk.

Notes.

Strain GLMC 1751, described here as Proliferodiscus ingens , was isolated from Prunus avium in Baden-Württemberg. Only the asexual morph of this fungus was observed. Asexual morphs have previously rarely been observed in the genus Proliferodiscus and no complete description is available. However, Baral and Kriegelsteiner (1985) and Dennis (1949) mention an asexual morph of Pr. pulveraceus . Dennis (1949) observed multilocular pycnidia with slender conidiophores (10-12 μm long) and spherical conidia (1 μm diam.), whereas Baral and Kriegelsteiner (1985) described oval conidia, measuring 1.5-1.7 × 1.2-1.4 μm, produced on verticillately branched conidiophores. In contrast to the description of Dennis (1949), the strains observed here produce unilocular pycnidia. Conidia of Pr. ingens are larger than conidia of Pr. pulveraceus in both descriptions. The asexual morph of Pr. ingens differs from that of the other Proliferodiscus strains observed in this study by producing larger, darker conidiomata, a different conidial shape and a lower growth rate.

The closest match in a blastn search with the ITS sequence of strain GLMC 1751 with 97.7% identity is " Hyaloscyphaceae sp. 2" strain ICMP 18979 from symptomless leaves of Nothofagus fusca in New Zealand (JN225935, Johnston et al. 2012).

Figures

Figure 5. Colony surface of analysed strains on OA medium. A Arboricolonus simplex GLMC 459 T B Cadophora africana CBS 120890 T C C. bubakii CBS 198.30 T D C. luteo-olivacea GLMC 1264 E C. novi-eboraci GLMC 1472 F C. obscura CBS 269.33 G C. prunicola CBS 120891 T H C. prunicola GLMC 1633 I C. ramosa GLMC 377 T J Minutiella pruni-avium GLMC 1624 T K Proliferodiscus ingens GLMC 1751 T L Proliferodiscus sp. GLMC 460. Cultures A, J-L after 4 wk. Cultures B-I after 2 wk. Strains with a superscript T are ex-type cultures.

Figure 15. Proliferodiscus ingens sp. nov. A conidiomata B conidia formed in conidiomata C-E, H, I conidiogenous cells lining the inner wall of a conidioma F, G detached conidiogenous cells A-I from OA A SM B-I LM. Scale bars: 300 μm (A), 5 μm (B applies to C-I).