Synfenestella Jaklitsch & Voglmayr, Persoonia 44: 35 (2019).
Index Fungorum number: IF 829759; Facesoffungi number: FoF 08191, 2 morphological species (Species Fungorum 2022), 2 species with molecular data.
Saprobic on host. Sexual morph: Ascomata globose, subglobose or pyriform, ostiolate, dark brown to black, immersed below bark epidermis, scattered, forming inconspicuous valsoid groups or conspicuous pseudostromatic pustules on pseudostromata or conidiomata of Diaporthales, surrounded and connected by thick-walled subicular hyphae, the latter sometimes short and subsetose in the ostiolar region. Peridium thicker and whitish inside in the apical region, pseudoparenchymatous, dark brown and thick-walled outside and pale to hyaline and thin-walled inside. Hamathecium consisting of numerous branched and anastomosing paraphyses with free ends in a matrix. Asci cylindrical to oblong, bitunicate, fissitunicate, with an ocular chamber, a short or long undulating stipe and simple or knob-like base, containing 4–8 ascospores in (obliquely) uniseriate arrangement. Ascospores ellipsoid, oblong to fusoid, sometimes subglobose, symmetric to slightly curved, with upper part often wider, initially 2-celled, hyaline and surrounded by a swelling sheath, developing additional transverse and longitudinal septa, turning yellow to golden brown (when fresh), finally dark brown with concolorous rounded ends, ends sometimes paler or apiculate upon germination, usually strongly constricted at the primary septum; in 3 % KOH surface smooth; turning dark olivaceous to blackish brown. Asexual morph: Pycnidia more or less globose, green to black, densely aggregating and fusing. Phialides lageniform, ampulliform, subglobose or subconical, sessile or produced on short simple conidiophores. Conidia cylindrical, oblong to allantoid, less commonly ellipsoid, 1-celled, hyaline, with 2 drops, smooth, produced on phialides and pegs (adapted from Jaklitsch & Voglmayr 2019).
Type species: Synfenestella sorbi (P. Karst.) Jaklitsch & Voglmayr
Notes: Synfenestella is characterised by globose, subglobose or pyriform ascomata, cylindrical to oblong asci, ellipsoid, oblong to fusoid, yellow to golden brown ascospores that turn dark olivaceous to blackish brown. Synfenestella can be differentiated from Parafenestella based on the swelling sheath visible in immature ascospores within the asci. Jaklitsch and Voglmayr (2019) reported that S. sorbi grows on Cytospora (Leucostoma morph) and is characterised by typical long-pedicellate asci with several aborted, distorted or even globose ascospores. Mirza (1968) described the asci of S. sorbi as long-pedicellate under Cucurbitaria sorbi. Jaklitsch and Voglmayr (2019) chose the lectotype of Cucurbitaria sorbi based on material collected on branches of Sorbus aucuparia (Rosaceae) in Finland and an epitype based on a specimen found on twig of Sorbus aucuparia (Rosaceae) in Austria. Synfenestella is a distinct and well-supported genus in Cucurbitariaceae. Molecular markers available for Synfenestella are ITS, SSU, BTUB, RPB2 and TEF-1.