Dothideales » Saccotheciaceae


Pseudosydowia Thambug. & K.D. Hyde, in Thambugala et al., Fungal Diversity 68: 140 (2014).

Index Fungorum number: IF 550733; Facesoffungi number: FoF 00105, 2 morphological species (Species Fungorum 2022), 2 species with molecular data.

Leaf spots amphigenous, subcircular, 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 morph: Ascostromata amphigenous, black, subepidermal, becoming erumpent, separate or aggregated in clusters of up to 8, globose, apical ostiole wall comprising 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 morph: Conidiomata pycnidial to avervular, amphigenous, subepidermal, dark brown, dehiscence by irregular rupture of the upper wall. Conidiomata wall comprising 3–6 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).


Type species: Pseudosydowia eucalypti (Verwoerd & du Plessis) Thambug. & K.D. Hyde


Notes: Pseudosydowia is characterised by amphigenous, black, subepidermal ascostromata, broadly ellipsoid to clavate asci, bi- to multiseriate, hyaline, (1-)3(-4)-septate ascospores. The asexual morph is characterised by pycnidial to avervular, amphigenous conidiomata, annellidic, integrated, indeterminate conidiogenous cells and medium brown to olivaceous-brown, ellipsoid to ovoid aseptate conidia. Pseudosydowia eucalypti previously known as Sydowia eucalypti was described by Verwoerd and du Plessis (1931) as Sphaerulina eucalypti. Crous et al. (2003) placed this species in Sydowia based on the asexual resemblance with other genera such as Sclerophoma and Hormonema mainly the thick-walled ascostromata and based on evidence from phylogenetic analyses. Crous et al. (2003) and Cheewangkoon et al. (2009) linked Sydowia eucalypti to the sexual morph of Selenophoma eucalypti which grouped with Aureobasidium and Hormonema taxa. In the study of Thambugala et al. (2014), Sydowia eucalypti grouped in Aureobasidiaceae hence, the genus Pseudosydowia was erected to accommodate Sydowia eucalypti. Pseudosydowia is a distinct genus in Aureobasidiaceae. Molecular markers available for Pseudoseptoria are ITS, LSU, BTUB, RPB2 and TEF-1.


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