Mycosphaerellales » Mycosphaerellaceae

Scirrhia

Scirrhia Nitschke ex Fuckel, Jb. nassau. Ver. Naturk. 23–24: 220 (1870) [1869–70].

Index Fungorum number: IF 4922; Facesoffungi number: FoF 08654, 24 morphological species (Species Fungorum 2022), 3 species with molecular data.

Associated with leaf spot. Sexual morph: Stromata subepidermal to erumpent, elongated, depressed globose, rounded, unilocular or with locules in many rows, opening by an apical pore. The stromatic wall is composed of vertically-orientated rows of brown to reddish brown cells of textura globosa or angularis and textura prismatica between locules; the outermost layers composed of black to dark brown cells and the cells of the inner layers brown to hyaline. Interthecial tissue compressed between asci and intact over the asci. Asci oblong or clavate, 8-spored, stalked, arising from compressed hyaline tissue at the base of the locule. Ascospores 2-seriate overlapping in the ascus, hyaline or yellowish, elliptic or obovoid, septate near the middle, not or slightly constricted at the septum, straight or often inequilateral, smooth, sometimes guttulate. Asexual morph: Unknown (adapted from Sivanesan 1984 and Videira et al. 2017).

 

Type species: Scirrhia rimosa (Alb. & Schwein.) Fuckel

 

Notes: Scirrhia is characterised by subepidermal to erumpent, elongate stromata, oblong or clavate, 8-spored asci and hyaline or yellowish, elliptic or obovoid ascospores. Müller and Arx (1962) placed Scirrhia in Mycosphaerellaceae based on the ascomata arranged in linear rows in a hypostroma of pseudoparenchymatal cells, bitunicate asci, and hyaline, uniseptate ascospores mentioning Scirrhodothis, Scirrhophragma and Metameris as possible synonyms. Scirrhia resembles the above three genera in having bitunicate asci, hyaline, uniseptate ascospores, pseudoparaphyses, and stromata with immersed, longitudinally arranged ascomata (Crous et al. 2011). Later, Arx and Müller (1975) referred Scirrhia to Dothideaceae. Barr (1972) and Sivanesan (1984) regarded the synonymy of Müller and Arx (1962) as doubtful and did not list them but accepted species that occurred on Gymospermae such as S. acicola and S. pini. Barr (1987) re-instated the generic synonyms and accepted Scirrhia in Dothideaceae. There is not much information available regarding the generic synonyms listed by Müller and Arx (1962) and the species that occurred on Gymospermae now belong to other genera namely Lecanosticta (L. acicola) and Dothistroma (D. pini) (Crous et al. 2009a). In the phylogenetic analysis of Crous et al. (2011d) based on LSU sequence data, S. aspidiorum (CBS 204.66) clustered in Didymellaceae, while S. brasiliensis (CBS 128762) clustered in Mycosphaerellaceae. The culture of S. aspidiorum (CBS 204.66) is Phoma herbarum and not related to S. brasiliensis (Crous et al. 2011). The placement of Scirrhia in Mycosphaerellaceae is doubtful and the taxonomy is obscure. More collections with DNA sequence data are needed to confirm the taxonomic position of the genus. Molecular markers available for Scirrhia are ITS, LSU and SSU.

 

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