Diaporthe rauvolfiae Y. Marin , C. Lamb., Kouam & L. Schweizer, 2023

Lambert, Christopher, Schweizer, Lena, Matio Kemkuignou, Blondelle, Anoumedem, Elodie Gisele M., Kouam, Simeon F. & Marin-Felix, Yasmina, 2023, Four new endophytic species of Diaporthe (Diaporthaceae, Diaporthales) isolated from Cameroon, MycoKeys 99, pp. 319-362 : 319

Diaporthe rauvolfiae Y. Marin, C. Lamb., Kouam & L. Schweizer sp. nov.

Fig. 7

Etymology.

Name refers to the host genus that this fungus was isolated from, Rauvolfia .

Description.

Conidiomata pycnidial in culture on PNA, globose or irregular, dark brown to black, solitary or in groups, embedded, erumpent, 210-450(-530) μm diam, white to cream conidial drops exuded from ostioles; conidiomatal wall yellowish brown to olivaceous brown or brown, composed of 1-2 layers, textura angularis. Conidiophores cylindrical to subcylindrical, tapering towards apex, base subhyaline to pale yellow or pale olivaceous, apex hyaline to subhyaline, densely aggregated, smooth-walled, (0-)1-2 septate, 9-19.5 × 1.5-3.5 μm. Conidiogenous cells phialidic, cylindrical to subcylindrical, tapering towards apex, hyaline, mostly terminal, 6.5-13.5 × 1.5-3 μm. Paraphyses not observed. Alpha conidia broadly fusiform to obovoid, hyaline, apex rounded or acute, base acutate, biguttulate to multiguttulate, aseptate, 6.5-9 × 2-3 μm. Beta conidia filiform, curved, tapering towards apex, hyaline, not guttulate, aseptate, 20-36.5 × 1-2 μm. Gamma conidia less frequent, fusiform to obovoid, straight to slightly curved, rarely sinuose, acutate ends or one acutate and other round, hyaline, multiguttulate, aseptate, (8-)9-13 × 1.5-2.5 μm.

Culture characters.

Colonies on PDA reaching 72-76 mm in 2 weeks, grayed yellow (160B-C) with white ring and transparent margins, cottony to slightly feathery, raised, lobate, margins filamentous; reverse grayed yellow (160B-C) with white ring and transparent margins. Colonies on MEA covering the surface of the Petri dish in 2 weeks, white to grayed white (156B), cottony to slightly feathery, raised, margins filamentous; reverse grayed green (197A) to gray brown (199A) with black (202A) center. Colonies on OA covering the surface of the Petri dish in 2 weeks, grayed white (156B-D), cottony to slightly feathery, raised, margins filamentous; reverse gray brown (199A).

Specimen examined.

Cameroon, Tonga, West Region, from Rauvolfia vomitoria , 19 Jun. 2019, E.G.M. Anoumedem (holotype CBS H-24924, culture ex-type CBS 148912 = STMA 18287).

Notes.

Diaporthe rauvolfiae was located in an independent branch far from other species of Diaporthe (Fig. 3 ). This species is characterized by the production of alpha, beta and gamma conidia, which were not observed in other species reported from Cameroon except of D. isoberliniae . This latter species differs from D. rauvolfiae in the length of the conidiophores (13-42 μm in D. isoberliniae vs 9-19.5 μm in D. rauvolfiae ), beta conidia (11.5-27.5 μm in D. isoberliniae vs 20-36.5 μm in D. rauvolfiae ) and gamma conidia (10-18.5(-21) μm in D. isoberliniae vs (8-)9-13 μm in D. rauvolfiae ). Both species are not phylogenetically related (Fig. 3 ).

Figures

Figure 3. Maximum Likelihood phylogram obtained (lLn = - 10678.2613) from the combined ITS, cal, his 3, tef 1 and tub 2 sequences of our strain and related Diaporthe spp. Diaporthe amygdali CBS 126679 T and D. eres CBS 138594 T were used as outgroup. Bootstrap support values ≥ 70 / Bayesian posterior probability scores ≥ 0.95 are indicated along branches. Branch lengths are proportional to distance. Novelties and emended taxa are indicated in bold. Type material of the different species is indicated with T. Figure legend refers to nucleotide substitutions per site.

Figure 7. Diaporthe rauvolfiae (ex-type strain CBS 148912) A conidioma in PNA B conidiomata in OA C conidiophores and conidia D alpha, beta and alpha conidia. Scale bars: 200 μm (A); 500 μm (B); 5 μm (C, D).