Dothideomycetes » Dothideomycetes, genera incertae sedis

Dianesea

Citation: Pem D et al. (2019) Mycosphere Notes 275-324: A morphotaxonomic revision and typification of obscure Dothideomycetes genera (incertae sedis). Mycosphere 10(1), 1115–1246

 

Dianesea Inácio & P.F. Cannon, Fungal Diversity 9: 72 (2002)

Saprobic on unidentified palm. Hemi-biotrophic as small leaf spots dispersed, rarely confluent, amphigenous, flat, black, variable in shape, generally elliptical, sometimes circular or irregular, forming dark brown to black leaf spots. Sexual morph: Ascostromata solitary, scattered, superficial to sometimes semi-immersed, conical, with single locule, ostiolate, coriaceous. Ostiole typically widely porate, broadly papillate. Peridium comprising several layers of brown and thick-walled cells of textura angularis. Hamathecium composed of 1–2 µm diam., of relatively thin, densely anastomosing, septate, branching, interascal pseudoparaphyses. Asci 8-spored, bitunicate, clavate to subcylindrical, with a short, narrow pedicel, thickened and rounded at the apex, with an ocular chamber. Ascospores uniseriate to partially overlapping, hyaline to pale olivaceous when immature, dark brown when mature, ellipsoidal or cylindrical to clavate, 1-septate, conspicuously constricted at the septum, smooth and thick-walled, surrounded by hyaline mucous sheath. Asexual morph: Coelomyceteous. Conidiomata variable in shape, pycnothyrial, subglobose to globose or elliptical, solitary, scattered, immersed to semi-immersed. Conidiophores indistinct. Conidiogenous cells holoblastic, enteroblastic, annellidic, cylindrical, and smooth. Conidia hyaline to greenish, cylindrical, straight or slightly curved, obtuse at apex, with small guttules.

 

Type species – Dianesea palmae (F. Stevens) Inácio & P.F. Cannon

 

Notes – The monotypic genus Dianesea was introduced by Inácio & Cannon (2002) for the type species Dianesea palmae which was previously known as Cocconia palmae. The latter was isolated from an unidentified palm in Costa Rica. The genus Dianesea is morphologically characterized by crustose, globose to subglobose ascostromata, clavate to subcylindrical 8-spored asci, ellipsoidal or cylindrical to clavate pale olivaceous 1-septate ascospores surrounded by hyaline mucous sheath. Cultures and sequences are unavailable. In this study, we re-examined the holotype specimen of Dianesea palmae (= Cocconia palmae). We observed both the sexual and asexual morphs. The sexual morph of the genus Dianesea resembles the genus Metameris (Botryosphaeriacae) except in spore morphology, particularly the narrow ascospores with a hyaline mucous sheath (Jayasiri et al. 2016). Species of Coccoidea Henn. resemble species of Dianesea, but the ascomata are formed as multiple distinct locules in peltate stromata, and the anamorph is acervular rather than locular (stromatic). The genus Coccoidea also has ascospores which are septate with septa close to the ends, in contrast to those of Dianesea where they have a ± median septum (Eriksson, 1981, Barr 1987, Sivanesan 1987, Kirk et al. 2001). The genus Rosenscheldiella also resembles Dianesea with its external stromatal shape, however these contain multiple ascomatal locules which produce colourless ascospores, but lack a distinct periphysate ostiole (Barr 1987). We therefore retain the genus Dianesea in Dothideomycetes, genera incertae sedis.

 

 

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