Pleosporales » Lophiotremataceae

Decaisnella

Decaisnella Fabre, Annls Sci. Nat., Bot., sér. 6 9: 112 (1879).

Index Fungorum number: IF 1434; Facesoffungi number: FoF 08274, 10 morphological species (Species Fungorum 2022), 1 species with molecular data.

Saprobic on host. Sexual morph: Ascomata immersed erumpent, separately or two or more beneath slight or well-developed blackened clypeus, globose, apex short papillate, reaching surface of clypeus or substrate, pore rounded. Peridium two layered, externally dark reddish brown with encrusted pigment, cells pseudoparenchymatous, internally lighter brown, cells more compressed. Asci bitunicate, peripheral, broadly cylindric, mostly 4-spored, some 2-spored. Pseudoparaphyses trabeculate in matrix. Ascospores dark reddish brown, end cells pallid at times, oblong, ends rounded; 7–9–13-septate, 1–2–3 longitudinal septa, not constricted at septa; wall broad, foveolate or smooth, at times remnants of gel coating visible over ends; contents globular when young, homogenous at maturity. Asexual morph: Unknown (adapted from Barr 1986).

Type species: Decaisnella spectabilis Fabre

Notes: Decaisnella is characterised by immersed erumpent ascomata, two layered peridium comprising pseudoparenchymatous cells and broadly cylindric, mostly 4-spored, some 2-spored asci and dark reddish brown ascospores. Saccardo (1883) transferred D. spectabilis to Teichospora based on morphology while other authors considered Decaisnella as a synonym of Teichospora. Decaisnella differs from Teichospora in ascospore size and septation, shape of ascomata, structure of peridium and type of pseudoparaphyses. Barr (1979) mentioned that the differences between Decaisnella and Teichospora were enough to justify their placement in different orders. Barr (1979) placed Decaisnella in Massariaceae replacing Titanella based on the shape of ascomata and distoseptate ascospores. The latter is a lichenized taxon, synonymized with Anthracothecium which belongs to the Pyrenulaceae. Barr (1986) re-established Decaisnella to accommodate taxa with dictyosporus ascospores and large ascomata, a wide peridium, a refractive apical ring surrounding an ocular chamber in the ascus, and distoseptation in immature ascospores. Decaisnella taxa are divided into two groups based on ascospore morphology with first one characterised by oblong ascospores with obtuse or rounded ends and the others with fusoid-ellipsoid ascospores with tapered ends (Barr 1990) Decaisnella resembles Aigialus, in having brown dictyosporus ascospores but differs in that Aigialus has ascomata which appears subglobose in anterior view, fusiform in sagittal section, and laterally compressed; and ellipsoidal to broadly fusiform ascospores in frontal view, narrowly fusiform in side view. Hyde et al. (2018) accommodated Decaisnella in a new family Phaeoseptaceae based on phylogenetic analysis of LSU, SSU, RPB2 and TEF1α sequence data. We follow Hyde et al. (2018) and treat Decaisnella in Phaeoseptaceae but more specimens with DNA sequence data are needed to confirm this systematic placement. Molecular markers available for Decaisnella are LSU, SSU, RPB2 and TEF1.

 

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