Dothideomycetes » Dothideomycetes, genera incertae sedis

Alascospora

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

 

Alascospora Raja, Violi & Shearer, Mycologia 102(1): 33 (2010)

Saprobic on petiole of Nymphaea odorata. Sexual morph: Ascomata superficial to partly immersed, scattered, globose, subglobose or hemispherical and flattened at the base, membranaceous, ostiolate, light brown, translucent when young, darkening with age. Peridium composed of hyaline to brown pseudoparenchymatic cells, with dark brown amorphous material deposited irregularly on the peridial surface, especially dense around the ostiole. Pseudoparaphyses sparsely branched, hyaline to brown, septate, filamentous, cylindrical, at times irregular, sometimes constricted at the septa. Asci bitunicate, fissitunicate, multiguttulate, thick-walled, globose to subglobose, short, pedicellate, containing eight irregularly arranged ascospores, without an ocular chamber, rounded at the apex. Ascospores ellipsoidal, 1-septate, septum thin, hyaline when immature becoming dark brown when mature, upper cell longer and wider than lower cell, with apical papillae and appressed sheath outlining the ascospores. Asexual morph: Undetermined.

 

Type species – Alascospora evergladensis Raja, Violi & Shearer

 

Notes – The monotypic genus Alascospora was described and introduced by Raja et al. (2010) with type species, Alascospora evergladensis. The latter was found on petiole of Nymphaea odorata submerged in freshwater in Florida and is characterized by light brown, translucent, membranous, ostiolate ascomata, with dark, amorphous material irregularly deposited on the peridium, near the ostiole; globose, fissitunicate, thick-walled asci; septate pseudoparaphyses; and 1-septate ascospores that are hyaline when immature, and surrounded by a hyaline gelatinous sheath that is wing-shaped and bordered on each side of the ascospores. This genus is also unique in its translucent sheath of ascospores which first swells in water and then condenses and darkens around mature ascospores, giving them a dark brown, verruculose look. Alascospora has been compared with Zopfia Rabenh, Pontoporeia (Durieu & Mont.) Kohlm., and Zopfiofoveola D. Hawksw, Caryospora de Not., in the family Zopfiaceae, as well as Testudina Bizz. and Verruculina Kohlm. & Volkm.-Kohlm. in family Testudinaceae. The asexual morph of this genus is unknown. Wijayawardene et al. (2017) placed this genus in Dothideomycetes genera incertae sedis. Cultures and sequences are unavailable. We re-examined the microslide of holotype from ILL herbarium under the code ILL40789. Raja et al. (2010) reported the presence of a translucent gelatinous sheath appearing as lateral wings in the border of immature ascospores. However, we could not observe this character from the type material as the microslide was not in good condition. The genus Alascospora is distinct from all other genera of the class Dothideomycetes. However, Alascospora can be compared to Natipusilla to some extent in having aquatic lifestyle, superficial globose ascomata, absence of pseudoparaphyses and ascospores surrounded by sheath. We retain the genus Alascospora in Dothideomycetes, genera incertae sedis.

 

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