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

Not sporulated. Diaporthebreyniae differs from its closest phylogenetic neighbour, D.durionigena by unique fixed alleles in three loci based on alignments of the separate loci included in the supplementary material: ITS positions 93 (indel), 159 (G), 436 (T), 437 (C), 451 (G), 453 (A), 485 (C); tef1 positions 46 (A), 62 (G), 80 (T), 100 (G), 146 (T), 274 (indel), 304 (A), 310 (G), 313 (C), 339 (T), 343 (A), 385 (G); tub2 positions 393 (A), 402 (indel), 426 (A), 565 (C), 675 (T), 713 (G), 770 (T).

Colonies on PDA reaching 55–70 mm in 2 weeks, greyed yellow (161A) with a white ring and transparent margins, lobate, cottony, raised, margins filamentous to fimbriate; reverse greyed yellow (161A–D) with transparent margins. Colonies on MEA covering the surface of the Petri dish in 2 weeks, white with greyed yellow center (161A), velvety to cottony, flat to raised in some zones, margins filamentous to fimbriate; reverse greyed yellow (162A–B). Colonies on OA covering the surface of the Petri dish in 2 weeks, white with greyed yellow ring (161D), velvety, flat, margins filamentous to fimbriate; reverse grey brown (199D).

Cameroon, Kala mountain, on leaves of Breyniaoblongifolia, 02 Jan. 2019, S.C.N. Wouamba (holotype: CBS H-24920, culture ex-type CBS 148910 = STMA 18284).

Diaporthebreyniae is introduced based only on molecular data since sporulation could not be induced in any media used. This species is located in a well-supported clade (97% bs / 1 pp) together with D.durionigena, D.passifloricola, D.rosae, D.thunbergiicola, D.ueckeri and D.vochysiae. The latter species has only been reported from Brazil occurring on different hosts, i.e. Stryphnodendronadstringens (Fabaceae, Fabales) and Vochysiadivergens (Vochysiaceae, Myrtales) (Noriler et al. 2019). Diaporthedurionigena has been only isolated from Duriozibethinus (Malvaceae, Malvales) in Vietnam (Crous et al. 2020, 2021). Diaporthepassifloricola has been found on Passiflorafoetida (Passifloraceae, Malpighiales) and Citrus spp. (Rutaceae, Sapindales) in China and Malaysia (Crous et al. 2016; Chaisiri et al. 2021; Dong et al. 2021), while D.rosae has been isolated from Rosa sp. (Rosaceae, Rosales), Magnoliachampaca (Magnoliaceae, Magnoliales) and Sennasiamea (Fabaceae, Fabales) in Thailand (Perera et al. 2018; Wanasinghe et al. 2018). Diaportheueckeri (syn. D.miriciae, Gao et al. 2016) has been reported in Australia, Colombia and the USA, on Cucumismelo (Cucurbitaceae, Cucurbitales), Glycinemax (Fabaceae, Fabales) and Helianthusannuus (Asteraceae, Asterales) (Thompson et al. 2015; Udayanga et al. 2015; López-Cardona et al. 2021). Diaporthethunbergiicola has been only isolated from Thunbergialaurifolia (Acanthaceae, Lamiales) in Thailand (Liu et al. 2015). The new species D.breyniae is the only of these species reported on Breynia (Phyllanthaceae, Malpighiales) in Africa. In fact, to the best of our knowledge, this is the first species of Diaporthe reported in Cameroon and occurring in this host.