Micraspis Darker, Can. J. Bot. 41(10): 1390 (1963)
Index Fungorum: IF3150
Leotiomycetes, Leotiomycetidae, Micraspidales, Micraspidaceae
Parasitc on the host plant. Sexual morph: see Darker (1963), Quijada et al. (2020). Asexual morph: Conidiomata black, pycnidial, amphigenous, scattered to gregarious, immersed, elliptical to irregular in outline, flattened, unilocular, glabrous. Ostiole absent, dehiscence by a longitudinal fissure of the apical wall. Conidiomatal wall composed of thick-walled, dark brown to black cells of textura angularis. Conidiophores arising from the inner wall layer of conidiomata, hyaline, cylindrical, branched at the base, septate, smooth-walled. Conidiogenous cells hyaline, enteroblastic, phialidic, ampulliform to cylindrical, integrated or discrete, determinate, smooth-walled. Conidia hyaline, fusiform to cylindrical or falcate, with obtuse apex and truncate base, straight or slightly curved, 1–3-septate, smooth-walled, guttulate (Darker 1963, Nag Raj and DiCosmo 1980).
Type species: Micraspis acicola Darker, Can. J. Bot. 41(10): 1390 (1963)
Notes: Micraspis is represented by M. acicula, described on Picea mariana (Pinaceae) from northern Ontario (Darker 1963). Another fungus Periperidium Darker, typified by P. acicola Darker, was described on the same host and it was regarded as a possible asexual morph (Darker 1963). Johnston et al. (2014) regarded Micraspis and Periperidium as congeneric, and recommended to use the name of Micraspis for the holomorph. Micraspis was originally placed in Phacidiaceae (Phacidiales) (Darker 1963). Later it was transferred to Tympaneae (DiCosmo et al. (1983) and Tympanidaceae (Phacidiales) Baral 2016). Quijada et al. (2020) revised Micraspis based on multigene phylogenetic analysis and morphological evidence, and introduced a new family Micraspidaceae (Micraspidales) for this genus. They also confirmed the connection between M. acicola and its purported asexual morph (= P. acicola) on symptomatic needles.
Micraspis acicola has hyaline, fusiform to cylindrical or falcate conidia and phialidic conidiogenous cells, which can be confused with Corniculariella and the asexual morph of Cryptosporella and Dermea. These genera are mainly separated by the conidiomatal structure and conidial septation. The conidiomata of Micraspis acicula are immersed, flattened, unilocular, while they are subcylindrical to conical or rostrate, and unilocular in Corniculariella, furfuraceous, discoid to subglobose, and unilocular in Cryptosporella, and furfuraceous or pruinose, pulvinate, and multilocular in Dermea (Nag Raj 1993, this study). In addition, the conidia of Micraspis are 1–3-septate, while they are 1–10-septate in Corniculariella, aseptate in Cryptosporella, and 0–1-septate in Dermea.
Distribution: Canada, Denmark, Ireland, Russia, UK USA (Nag Raj and DiCosmo 1980, Wijayawardene et al. 2017, Quijada et al. 2020).
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.