Pseudosydowia eucalypti (Verwoerd & du Plessis) Thambug. & K.D. Hyde, Fungal Diversity 68: 140. 2014.

Index Fungorum number: IF 550734 ; Facesoffungi number: FoF 00106

BasionymSphaerulina eucalypti Verwoerd & du Plessis, S. Afr. J. Sci. 28: 296. 1931.

Synonyms: ≡ Sydowia eucalypti (Verwoerd & du Plessis) Crous, Sydowia 55: 143. 2003.

                     ≡ Selenophoma eucalypti Crous et al., Mycol. Res. 99: 648. 1995.

Leaf spots amphigenous, sub circular, becoming confluent, covering large areas of the leaf, pale brown, surrounded by a narrow, raised, dark brown margin. Mycelium internal, medium brown, consisting of septate, branched, smooth hyphae. Sexual state: Ascostromata amphigenous, black, subepidermal, becoming erumpent, separate or aggregated in clusters of up to 8, globose, apical ostiole wall consisting of several layers of dark brown textura angularis. Asci 8-spored, bitunicate, fasciculate, broadly ellipsoid to clavate, straight to slightly curved, subsessile with a well-developed ocular chamber. Ascospores overlapping, bi- to multiseriate, hyaline, (1-)3(−4)-septate at maturity, constricted at the median septum, aguttulate, thin-walled, straight to slightly curved, obovoid to ellipsoid with obtuse ends, tapering towards both ends, but more prominently towards the lower end (Crous et al. 2003). Asexual state: Conidiomata pycnidial to avervular, amphigenous, subepidermal, dark brown, dehiscence by irregular rupture of the upper wall. Conidiomata wall comprising 3 to 6 layers of dark brown to black cells of textura angularis. Conidiophores reduced to conidiogenous or hyaline, smooth, branched, 1 to 7-septate, constricted at the septa after incubation in moist chambers. Conidiogenous cells annellidic, integrated, indeterminate, formed from the inner cells of the conidiomatal wall, hyaline to pale brown, smooth-walled, slightly thick-walled, ampulliform to cylindrical, slightly tapered toward the apex. Conidia aseptate, medium brown to olivaceous-brown, ellipsoid to ovoid, aguttulate, thin-walled (Crous et al. 2003; Cheewangkoon et al. 2009).

Notes Sydowia eucalypti was originally described by Verwoerd and du Plessis (1931) as Sphaerulina eucalypti. Crous et al. (2003) accommodated this species in Sydowia based on its Sclerophoma and Hormonema asexual states and the thick-walled ascostromata. His phylogenetic analysis also showed that of Sydowia eucalypti clustered in Dothioraceae, Dothideales. Sydowia eucalypti is linked to the sexual morph of Selenophoma eucalypti, which clustered with other Aureobasidium and Hormonema species (Crous et al. 2003; Cheewangkoon et al. 2009). In our study, Sydowia eucalypti clustered in Aureobasidiaceae with species of Aureobasidium, Selenophoma and Kabatiella. Therefore, we propose a new monotypic genus Pseudosydowia for Sydowia eucalypti.

Fig. 1Pseudosydowia eucalypti (CPC 5247). A–D. Disease symptoms. E. Conidiomata giving rise to spore masses on host leaf. F. conidia of Selenophoma morph. G. Colony on MEA. H. Colony on pine needle agar. I, J. Conidia of coniothyrium-like synasexual morph. K. Conidiogenous cell. L–N. Asci and ascospores. Scale bars: E, G = 10 mm; F, I = 20 μm; H = 100 μm; L–N = 40 μm (from Cheewangkoon et al. 2009).