Fungalpedia – Note 1662, Tetranacrium
Tetranacrium H.J. Huds. & B. Sutton
Index Fungorum, Facesoffungi, MycoBank, GenBank.
Classification: Incertae sedis, Incertae sedis, Incertae sedis, Incertae sedis, Pezizomycotina, Ascomycota, Fungi
Saprobic on the host plant in terrestrial habitat or on decayed wood submerged in freshwater habitats (Hudson and Sutton 1964, Shearer and Crane 1971). Sexual morph: undetermined. Asexual morph: Conidiomata blackish brown to black, stromatic, pycnidial, solitary or gregarious, subcuticular, eventually erumpent, carbonous, subglobose in section view, unilocular, glabrous. Ostiole absent, dehiscence by longitudinal fissure of the apical wall. Conidiomatal wall composed of thick-walled, dark brown cells of textura angularis in the exterior, becoming pale brown to hyaline cells towards hymenium. Conidiophores arising from inner wall layer of conidiomata. Conidiogenous cells hyaline, holoblastic, cylindrical to doliiform, determinate, smooth-walled. Conidia hyaline, tetraradiate, composed of one vertical arm and three or four equidistant horizontal arms, septate, smooth-walled, guttulate; arms originating from a central, spherical basal cell, with a truncate base, tapered towards the apex, constricted near the point of attachment to the basal cell (adapted from Hudson and Sutton 1964, Morgan-Jones 1977, Sutton 1980).
Notes: The hyaline, septate, four or five radiate conidia in Tetranacrium is reminiscent of Crucellisporiopsis, Crucellisporium, Eriosporella, Quadricladium, Tetracrium and Tricornispora (Sutton 1980, Nag Raj 1993, Punithalingam 2003, Seifert et al. 2011). Of these genera, Quadricladium, Tetracrium and Tricornispora are recognized as hyphomycetes (Seifert et al. 2011). Crucellisporiopsis, Crucellisporium, Eriosporella have clavate to subcylindrical main axes and filiform arms, whereas Tetranacrium has a spherical, centrally located basal axis and clavate to subcylindrical arms. The differences among Crucellisporiopsis, Crucellisporium and Eriosporella are discussed under Crucellisporiopsis.
Tetranacrium was re-described and re-illustrated by Morgan-Jones et al. (1972e) and Sutton (1980). Apart from the type species, the other two species listed in Index Fungorum (2019), T. eugeniae Subhedar & V.G. Rao on Eugenia jambolana (Myrtaceae), and T. malpighiacearum J.L. Bezerra & Poroca on Malpighiaceae, have not been re-examined. Due to a lack of molecular sequence data for T. gramineum, the placement of this genus is undetermined.
Type species: Tetranacrium gramineum H.J. Huds. & B. Sutton, Trans. Br. mycol. Soc. 47(2): 202 (1964)
Other accepted species: Species Fungorum – search Tetranacrium.
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.