Mycosphaerellales » Mycosphaerellaceae


Melanodothis R.H. Arnold, Can. J. Bot. 49: 2188 (1972).

Index Fungorum number: IF 3067; Facesoffungi number: FoF 08626, 1 morphological species (Species Fungorum 2022), no molecular data available.

Associated with leaf spot. Sexual morph: Ascostromata arising from a hypostroma formed within the ovary and perigynum, black, subglobose, multilocular, wall composed of a textura angularis with pseudoparenchymatic cells. Locules in a single layer beneath the surface of the stroma, each with an ostiole. Pseudoparaphyses absent. Asci oblong to rarely oblong-pyriform, sessile, 8-spored, arising from a basal cushion of pseudoparenchymatic cells. Ascospores hyaline, one celled, thick-walled, narrowly ellipsoidal, with ends sometimes narrowly and abruptly tapered. Asexual morph: Microconidial locules are formed in the early stages of ascostromata. Microconidia (spermatia) narrowly oblong, hyaline, formed on short projections on the hyaline cells lining the microconidial cavity. Conidiophores indeterminate. Conidiogenous cells holoblastic. Macroconidia ramularia-like, hyaline, smooth, catenate, branched or unbranched, cylindrical, aseptate or uniseptate, with a disc-like hilum at each end. Blastoconidia formed singly at the apex of hyphae in the periphery of the colony or on the long cylindrical conidia as secondary conidia, one celled, hyaline, smooth, ovoid (adapted from Arnold 1971; Videira et al. 2017).

 Type species: Melanodothis caricis R.H. Arnold

Notes: Melanodothis is characterised by black, subglobose, multilocular ascostromata, oblong-pyriform, aparaphysate, sessile asci and hyaline, one-celled, thick-walled, narrowly ellipsoidal ascospores. The asexual morph is characterised by holoblastic conidiogenous cells, ramularia-like, hyaline, smooth macroconidia, and one-celled, hyaline, smooth, ovoid blastoconidia. In the phylogenetic analysis of Videira et al. (2017), an ex-type culture of M. caricis clustered in Cladosporiaceae and the authors suggested that Melanodothis is an older name for Davidiella. The name currently used for Davidiella is the asexual morph, Cladosporium (Bensch et al. 2012; Videira et al. 2017). Arnold (1971) mentioned the occurrence of an ascostroma with pseudothecial locules which has also been reported in Davidiella (Schubert et al. 2007). Melanodothis caricis also seems to be related to Ramularia caricis collected from North America but this relationship must be confirmed with molecular data (Braun 1998). The placement of Melanodothis in Mycosphaerellaceae is doubtful. Fresh collections with DNA sequence data are needed to confirm this generic placement.


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