Botryosphaeria
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: Saccardo (1877) amended Botryosphaeria and excluded hypocreaceous species. B. berengeriana was designated as the type of Botryosphaeria by Höhnel (1909) but the species was missing in the original description of the genus. B. quercuum was proposed as the type species by Theissen and Sydow (1915) based on Saccardo’s (1877) emendation and this was followed by Arx and Müller (1954). Still, B. quercuum was found unsuitable as the type because it was not one of the original species and a lectotype, B. dothidea was proposed by Barr (1972) as it was one of the original species described and it fits in with Saccardo’s (1877) emendation. B. dothidea was a synonym of B. berengeriana, the type designated by Höhnel’s (1909). A revision of B. dothidea was carried out by Slippers et al. (2004a) based on the type specimens and fresh collections and a neotype as well as an epitype was designated. The taxonomy of Botryosphaeria remained controversial for several years as it rested on morphological description of the ascomata and host associations and various names were proposed. Botryosphaeria species are challenging to separate based on sexual morph characters, still 183 taxa were re-examined and reduced to 11 species by Arx and Müller (1954). These synonymies have not always been accepted because asexual morphs characters were not considered and it was difficult to segregate species based on sexual morph characters (Shoemaker 1964, Sivanesan 1984, Slippers et al. 2004). Botryosphaeria is usually characterised by ascospores which are hyaline and aseptate, becoming pale brown and septate when mature (Shoemaker 1964, Sivanesan 1984, Denman et al. 2000, Alves et al. 2004, Phillips et al. 2005). Arx and Müller (1954) included Dothidea visci in Botryosphaeria as B. visci based on the brown ascospores and later, the dark-spored Neodeightonia was also included in Botryosphaeria (Arx & Müller 1975). Based on these facts, Arx and Müller (1954, 1975) widened the concept of Botryosphaeria and included species with brown ascospores. In the phylogenetic analysis of Phillips et al. (2005), two species of Dothiorella clustered in Botryospheria and the sexual morphs of Dothiorella were described as Botryosphaeria with brown, uniseptate ascospores. Consequently, Luque et al. (2005) defined an extra dark-spored B. viticola, with a Dothiorella asexual morph. Several asexual genera were linked with Botryosphaeria sensu lato (Denman et al. 2000) such as Diplodia, Dothiorella, Fusicoccum, and Lasiodiplodia. Crous et al. (2006) demonstrated that Botryosphaeria sensu lato comprised of 10 phylogenetic lineages, each of which relates to diverse asexual genera and restricted the use of Botryosphaeria to B. dothidea and B. corticis. Currently, Botryospheria is a distinct and the type genus of Botryosphaeriaceae. Molecular markers available for Botryosphaeria are ITS, LSU, SSU, Actin, BTUB, Histone, RPB2 and TEF-1.
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