Dermea
Dermea Fr., Syst. orb. veg. 1: 114 (1825)
= Gelatinosporium Peck, Ann. Rep. Reg. Univ. St. N.Y. 25: 84 (1873) [1872]
= Foveostroma DiCosmo, Can. J. Bot. 56(14): 1682 (1978)
Leotiomycetes, Leotiomycetidae, Medeolariales, Dermateaceae
Saprobic on plant host in terrestrial habitat. Sexual morph: Apothecia dark brown to black, erumpent, seperate or caespitose, circular to undulate, sessile or narrowed below to substipitate, hard, leathery in consistency, softer and more fleshy when moist. Hymenium at first concave, becoming plane or convex, roughened, sometimes cracked, occasionally slightly umbilicate, black, olivaceous to greenish when moist. Asci cylindrical-clavate, mostly 8-spored. Ascospore hyaline to yellow-brown, ellipsoid to ellipsoid-fusiform, 1–7-septate. Paraphyses numerous, filiform, exceeding the asci in length and forming an epithecium (Groves 1946). Asexual morph: Conidiomata yellowish to brown, solitary to gregarious, subperidermal in origin, immersed to partly erumpent at maturity, stromatic, subglobose to depressed globose, multilocular, thick-walled, glabrous. Ostiole short, centrally located. Conidiomata wall composed of thick-walled, hyaline cells of textura intricata to textura epidermodea. Conidiophores hyaline, cylindrical to subcylindrical, septate, broader and branched at base, formed from inner cells of conidiomata. Conidiogenous cells hyaline, enteroblastic, phialidic, cylindrical to subcylindrical, discrete or integrated, indeterminate, with periclinal thickening in the collarette zone, smooth. Conidia hyaline, elongate-fusiform to subfiliform, tapering towards both ends, curved or straight, aseptate or 1-septate, smooth, guttulate.
Type species: Dermea cerasi (Pers.) Fr., Syst. orb. veg. 1: 115 (1825)
Notes: Dermea was proposed by Fries (1825) to accommodate a group of inoperculate Discomycetes, but he did not designate a type species for this genus. Subsequently, Tulasnes (1865) chose D. cerasi (Pers.) Fr. as the type species, because it is one of the most frequently collected and best known Dermea. According to Article 20 of the International Rules of Nomenclature, Seaver and Velasquez (1933) agreed that D. cerasi can be accepted as the type of genus. Based on D. cerasi, 16 species from North American were recognized in Dermea by Groves (1940, 1946).
Groves (1946) linked Dermea cerasi to its asexual morph Micropera drupacearum Lév. which is now synonymized under Foveostroma drupacearum (Lév.) DiCosmo based on a culture study. Therefore, he thought that the asexual morph of Dermea species belonged to Foveostroma DiCosmo, with the exception of D. acerina (Peck) Rehm, whose asexual morph was considered to be in Naemosphaera P. Karst. (Groves 1946, DiCosmo 1978). Since the morphology of conidia (shape) is remarkably constant, Grove (1946) divided the genus into four groups, viz. Cerasi group, Padi group, Prunastri group and the fourth group consists of the single species D. acerina (Peck) Rehm. However, this classification has not been confirmed by molecular study (Abeln et al. 2000). In addition, characters of sexual morph that are thought to be specific for a certain group appeared to be polyphyletic. For example, D. libocedri J.W. Groves and D. viburni J.W. Groves both belong to Cerasi group, but the asci of D. libocedri tend to approach certain species of the Prunastri group in shape, while D. viburni are more like those of the Padi group (Groves 1946).
In this study, phylogenetic tree reconstructed utilizing multi-gene of LSU, ITS and rpb2 sequence data show that two new collections from Italy cluster with D. cerasi with high bootstrap value Fig. (129). Morphologically, these two strains largely resemble Foveostroma drupacearum, type species of the genus, in the form of conidiomata, conidiogenous cells and conidia, but differ in dimensions of conidiomata. However, structure of conidiomata in Foveostroma species are varied and this cannot be used as a criterion in species or generic identification. Combining both phylogeny and morphology outlined above, Foveostroma is confirmed as the asexual morph of Dermea and this agrees with the concept of Groves (1946).
Gelatinosporium is similar to asexual morph of Dermea (= Foveostroma drupacearum) in having pulvinate, unilocular to multilocular conidiomata without preformed ostioles, opening by breakdown of the apical wall, and phialidic conidiogenous cells and fusiform to lunate, 1-septate conidia. The only differences between these two genera are the conidiomatal structure. Gelatinosporium has pale brown to hyaline cells of textura oblita in the basal part, while Dermea has hyaline cells of textura intricata to textura epidermodea in the basal part (Sutton 1980, this study). However, the conidiomatal wall structure as single characters have insufficient value to separate genera in coelomycetes, therefore Gelatinosporium is reduced to a synonym of Dermea.
Distribution: Austria, Belgium, Canada, Hungary, Italy, Sweden, UK, USA, (Groves 1946, Sutton 1980, this study).
References:
Li WJ, McKenZie EHC, Liu JK, Bhat DJ, Dai DQ, Caporesi E, Tian Q, Maharachcikumbura SSN, Luo ZL, Shang QJ, Zhang JF, Tangthirasunun N, Karunarathna SC, Xu JC, Hyde KD (2020) Taxonomy and phylogeny of hyaline-spored coelomycetes. Fungal Diversity 100: pages279–801.
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