Pleosporales » Didymellaceae

Macroventuria

Macroventuria Aa, Persoonia 6: 359. 1971.

Index Fungorum number: IF 2972; Facesoffungi number: FoF 08226, 2 morphological species (Species Fungorum 2021), 2 species with molecular data.

Saprobic on host. Sexual morph: Perithecia piriform, somewhat columnar or more often globose with a conspicuous papilla. Perithecial wall mostly thick on the outer side with 14 layers of thick-walled, textura globulosa or textura prismatica, often flattened cells, passing on the outer side of perithecium, especially at the base, into brownish, strongly interwoven hyphae, septate and often about 37 μm thick; on the inner side, the wall passes into some layers of hyaline, prismatic or flattened, thin-walled cells, variable in diameter, above the asci more or less globose, very thin-walled and partly disappearing at maturity. Setae on perithecia of two types; lower ones on the upper part of the perithecial body and the lower part of the papilla, brownish, often very stiff, with 26, mostly 24 septa, at the base sometimes swollen and up to 10 μm broad, somewhat tapering to the top and mostly rounded, but rarely pointed; second type of setae on the top of the papilla, sub-hyaline or only faintly brownish near the base, with 14 septa; the two types of setae usually separated by a zone without setae, but sometimes with intermediate forms occurring on the side of the papilla; the first type may also occur on the mycelium or on the chlamydospore like initials of the perithecia from the very beginning of their development. Asci restricted in number, arranged parallel or almost parallel to one another, cylindrical or sack-like, the widest part in the middle or just below the middle, almost without a stalk, rounded at their base, broadly rounded at the top, bitunicate, the inner tunica suddenly elongating at maturity, 8spored, the spores in 13 series. Asci surrounded by very slender paraphyses, composed of broad cells, sometimes completely disappearing at maturity.  Ascospores 2celled, the cells equal in size, constricted at the septum, tapering toward the ends or broadly rounded at one end and somewhat tapering toward the other end, the contents very thin, greenish granular. Asexual morph: Unknown (Adapted from van der Aa 1971).

 

Type species: Macroventuria anomochaeta Aa

 

Notes: Macroventuria was introduced by van der Aa (1971) with M. anomochaeta as type species. Macroventuria is characterized by piriform perithecia, perithecial wall comprising cells of textura globulosa or textura prismatica, cylindrical or sack-like asci and 2celled ascospores. Macroventuria was assigned to Venturiaceae (van der Aa 1971) then referred to other families such as Pseudosphaeriaceae (Barr 1982) and Pleosporaceae (Eriksson and Hawksworth 1986; Kodsueb et al. 2006). Macroventuria resemble Venturia by their setose pycnidia, but differ in their ascospore morphology and restricted number of the asci. Aveskamp et al. (2010) placed Macroventuria in Didymellaceae based on multigene phylogenetic analyses.  Macroventuria differs from Didymella in having setae on the pseudothecia whereas ascomata in Didymella are usually glabrous. Currently, Macroventuria is a distinct and well-supported genus in Didymellaceae.

 

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