Pseudosydowia K. M. Thambugala & K. D. Hyde gen. nov., Index Fungorum number: IF 550733.
Etymology: Referring to its similarity with Sydowia
Type species: Pseudosydowia eucalypti (Verwoerd and du Plessis) K. M. Thambugala & K. D. Hyde sp. comb. Nov., Index Fungorum number: IF 550734; Facesoffungi number: FoF00106
≡ Sydowia eucalypti (Verwoerd & du Plessis) Crous, in Crous et al., Sydowia 55(2): 143 (2003)
≡ Selenophoma eucalypti Crous, C.L. Lennox & B. Sutton, Mycol. Res. 99(6): 648 (1995)
≡ Sphaerulina eucalypti Verwoerd & du Plessis, S. Afr. J. Sci. 28: 296 (1931)
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, sub sessile 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 (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.