Minutiella pruni-avium 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

Minutiella pruni-avium S.Bien & Damm sp. nov. Figures 5J , 14

Type.

Germany, Baden-Württemberg, orchard west of Nussbach, 48°31'55.8"N, 8°00'52.4"E, from brown necrosis in wood of Prunus avium , 23 Aug 2016, S. Bien leg., GLM-F110704 - holotype; GLMC 1624 = CBS 145513 = DSM 109150 - culture ex-type.

Etymology.

Name refers to the host species, Prunus avium .

Description.

Sexual morph not observed. Asexual morph on SNA. Vegetative hyphae hyaline, smooth-walled, septate, branched, 1-3 μm wide, lacking chlamydospores. Sporulation abundant, conidia formed directly on hyphal cells, in conidiomata and by microcyclic conidiation. Conidiophores on hyphae reduced to conidiogenous cells, conidiogenous loci formed terminally. Conidiogenous cells enteroblastic, hyaline, smooth-walled, mostly reduced to mere openings with collarettes formed directly on hyphal cells, discrete phialides rare, navicular, constricted at the base, 5.5-14.5 × 1.5-2.5 μm; collarettes rarely visible or flaring, <0.5-3 μm long, opening 0.5-1.5 μm, periclinal thickening sometimes visible. Conidia aggregated in masses around the hyphae, hyaline, smooth-walled, aseptate, oblong to ellipsoidal, mostly straight, sometimes slightly curved, with both ends rounded, sometimes with a prominent scar on one end, (2.5-)3-5(-6) × 1-1.5(-2) μm, mean ± SD = 3.9 ± 0.9 × 1.4 ± 0.2 μm, L/W ratio= 2.8. Conidiomata produced on OA in 2-4 wk; solitary or aggregated, globose to subglobose, unilocular, immersed to superficial, 50-340 μm wide, olivaceous to black, mostly glabrous, sometimes with a few hairs, opening with an irregular rupture. Conidiophores reduced to conidiogenous cells. Conidiogenus cells enteroblastic, hyaline, smooth-walled, conidiogenous loci formed terminally, discrete phialides, globose to ampulliform or navicular, 3.5-7.5 × 2-3.5 μm, opening 0.5-1 μm, periclinal thickening sometimes visible. Conidia hyaline, smooth-walled, cylindrical to ellipsoidal, sometimes slightly curved, with both ends rounded, (2.5-)3-4.5(-6) × (1-)1.5-2(-3) μm, mean ± SD = 3.8 ± 0.8 × 1.7 ± 0.4 μm, L/W ratio = 2.2. Microcyclic conidiation occurs from minute collarettes at one or both ends of primary conidia that develop into swollen mother cells, often thick-walled, sometimes septate,> 5 μm long, 2-3.5 μm wide.

Culture characteristics.

Colonies on OA flat with entire margin, white to saffron, with scattered umber spots due to conidiomata formation, aerial mycelium lacking, spore masses oozing from conidiomata buff, reverse white to buff, 4-8 mm diam. in 2 wk, 6-10 mm diam. in 4 wk. Colonies on SNA flat with entire margin, white, lacking aerial mycelium, reverse same colour; <1-2 mm diam. in 2 wk, 6-8 mm diam. in 4 wk.

Notes.

Two strains of Minutiella pruni-avium were isolated from wood of Prunus avium . The LSU sequences of these strains differ in three and one nucleotides from those of M. tardicola and Minutiella sp., respectively. The ITS region shows 11 differences to M. tardicola and 9 differences to Minutiella sp. The TUB sequence of M. tardicola and Minutiella sp. differ in one nucleotide, however, in 35 and 33 nucleotides compared to M. pruni-avium . Minutiella pruni-avium differs from Minutiella tardicola and the strains of Minutiella sp. by forming larger conidiomata, longer discrete phialides and flaring collarettes of up to 3 μm.

The closest match in a blastn search with the ITS sequence of strain GLMC 1624 is the type strain of Minutiella tardicola CBS 121757 with 97.9% identity (NR132006, Damm et al. 2010).

Additional material examined.

Germany, Baden-Württemberg, orchard west of Nussbach, 48°32'11.3"N, 8°01'01.3"E, from brown necrosis in wood of Prunus avium , 23 Aug 2016, S. Bien leg., GLM-F110750, culture GLMC 1667 = CBS 145514 = DSM 109149.

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 14. Minutiella pruni-avium sp. nov. A, B conidiomata C-F conidiogenous cells lining the inner wall of a conidioma G conidia formed in conidiomata H-K, P-V conidiogenous cells formed on hyphal cells (arrows indicate conidiogenous openings) L-O mother cells W conidia formed on hyphal cells A-G from OA H-W from SNA A, B SM, C-W LM. Scale bars: 200 μm (A applies to B), 5 μm (C applies to D-W).