Botryosphaeria Ces. & De Not., Comm. Soc. crittog. Ital. 1(fasc. 4): 211 (1863).
Index Fungorum number: IF 183247; Facesoffungi number: FoF 00141, 111 morphological species (Species Fungorum 2022), 13 species with molecular data.
Mycelium immersed, consisting of branched, septate, smooth, hyaline hyphae. Sexual morph: Ascomata eustromatic, scattered, solitary, aggregated or forming botryose clusters, externally black, uniloculate, with a thick pseudoparenchymatic wall composed of textura angularis or textura globosa with the outer layers blackened and their cells more thickened, ostiolate, embedded in the substrate and partially erumpent at maturity. Pseudoparaphyses thin-walled, hyaline, frequently septate, constricted at the septa, deliquescing from the basal parts when the asci mature. Asci clavate or cylindric-clavate, stipitate, bitunicate, ectotunica thin, endotunica rather thick, 3-layered (sensu Eriksson 1981), with a prominent apical chamber, 8-spored, developing on a broad basal hymenial layer. Ascospores irregularly biseriate in the ascus, hyaline, sometimes becoming pale brown with age, thin-walled, ovoid, fusoid, fusoid-ellipsoid, usually widest in the middle, straight or inequilateral, smooth, one-celled sometimes becoming 1–2 septate with age, contents smooth or granular, may be guttulate. Asexual morph: Conidiomata stromatic, pycnidial, solitary or aggregated, often occurring within the same stroma as the ascomata, walls composed of dark brown, thick-walled textura angularis, becoming thin-walled and hyaline towards the inner layer. Ostioles indistinct to well-defined, round or irregular. Paraphyses hyaline, cylindrical, tapering to rounded ends, septate, arising between the conidiophores and conidiogenous cells. Conidiophores when present hyaline, cylindrical, branched at the base, smooth, 0–1 septate. Conidiogenous cells enteroblastic, integrated, hyaline, smooth, cylindrical, first-formed conidium holoblastic, determinate or proliferating percurrently with 1–2 indistinct annellations, or proliferating at the same level resulting in typical phialides (sensu Sutton 1980) with periclinal thickenings. Conidia hyaline, sometimes becoming olivaceous or darker with age, thin-walled, smooth, aseptate, occasionally forming one or two septa with age or before germination, with shapes varying from elliptical to fusiform or clavate, finely guttulate, apex subobtuse to obtuse, base conspicuously truncate with a minute marginal basal frill (Adapted from Phillips et al. 2013).
Type species: Botryosphaeria dothidea (Moug.) Ces. & De Not.
Notes: Botryosphaeria was introduced by Cesati and De Notaris (1863) with B. dothidea as type species. Botryosphaeria is characterized by septate, smooth, hyaline hyphae, clavate or cylindric-clavate, stipitate asci and ovoid, fusoid, fusoid-ellipsoid, one-celled sometimes becoming 1–2 septate ascospores. Cesati and De Notaris (1863) accepted nine species of Botryosphaeria but did not designate a type species. Saccardo (1877) revised the genus and excluded hypocreaceous species. Von Höhnel (1909) chose B. berengeriana De Not. as the type since Cesati and De Notaris (1863) did not designate a type species but this was not followed by consequent authors. Theissen and Sydow (1915) mentioned B. quercuum as the type species which might be considered as generic lectotypes since it represented Saccardo’s (1877) emendation of Botryosphaeria. Since B. quercuum was not an original species of the genus, it was inappropriate as a type and was not followed by consequent authors. Von Arx and Müller (1954) re-studied 183 species and synonymized them to 11 species mostly under B. dothidea and B. quercuum and provided nine new combinations. von Arx and Müller (1954) did not consider asexual morphs characters in his study and hence his synonymies have not been accepted by other authors (Shoemaker 1964; Sivanesan 1984; Slippers et al. 2004a). von Arx and Müller (1954) broadened the morphological concept of Botryosphaeria and transferred Dothidea visci to Botryosphaeria based on the brown ascospores. Barr (1972) suggested B. dothidea as a lectotype as it was one of the original species described, it fitted with Saccardo’s (1877) emendation and it is a previous synonym of B. berengeriana, the type species designated by von Höhnel (1909) and this proposal was widely used by consequent authors. von Arx and Müller (1975) referred Neodeightonia subglobosa in Botryosphaeria based on the dark-spored ascospores and Neodeightonia was synonymized to Botryosphaeria. Around eighteen asexual genera are related with Botryosphaeria s. lat. (Denman et al. 2000) including Diplodia, Dothiorella, Fusicoccum, and Lasiodiplodia. Slippers et al. (2004) re-examined the type specimen B. dothidea and designated a neotype and epitype based on morphology and phylogenetic analysis of ITS, BTUB and TEF-1. Members of Botryosphaeria are delineated based on the ascomatal morphology, host relationship which resulted in an increase of names in the genus. Crous et al. (2006) reported that Botryosphaeria s. lat. comprises 10 phylogenetic lineages based on phylogenetic analysis of LSU gene. Several authors added new species to Botryosphaeria (Taylor et al. 2003; Alves et al. 2004; Phillips et al. 2005; Zhou et al. 2016). Botryosphaeria is a distinct and type genus of Botryosphaeriaceae. However, several species lack molecular data and might belong to other genera. Molecular markers available for Botryosphaeria include LSU, SSU, ITS, TEF-1 and RPB2.