Acarella Syd., Annls mycol. 25(1/2): 123 (1927)
MycoBank number: MB 7005; Index Fungorum number: IF 7005; Facesoffungi number: FoF 09021
Parasitic or epiphytic on the surface of living leaves. Sexual morph: Undetermined. Asexual morph: Pycnidia hypophyllous, dark brown to black, superficial, in groups with irregular margins, sometimes sparsely scattered or not entirely distributed on surface of leaves. Conidiophores straight or slightly curved, hyaline, mostly reduced to conidiogenous cells. Conidiogenous cells phialidic or enteroblastic-percurrent, cylindrical to elliptical, septate, rough and thick-walled. Conidia ellipsoidal to cylindrical, solitary, hyaline to olivaceous-brown, 1-septate, apparently with 2- guttules.
Type species – Acarella costaricensis Syd.
Notes – The genus Acarella was described and introduced by Sydow (1927) with the type species, A. costaricensis. Acarella costaricensis was found on unidentified leaves in San Pedro de San Ramon, Peru. Morphologically, this genus is characterized by scattered, small and completely superficial pycnidia with a thin peridium. Conidia are ellipsoid to cylindrical. The sexual morph of this genus is unknown. Species of Acarella are distributed in Central America (Wijayawardene et al. 2017). Cultures and sequences are unavailable. Acarella costaricensis and Perizomella inquinans were isolated from Phoebe costaricana in Costa Rica and is morphologically similar in having ovoid to ellipsoidal or rarely subglobose, brown to dark brown conidia, with transverse
hyaline band, formed on phialidic, hyaline conidiogenous cells lining the inner cavity of the upper wall. Therefore, considering the host relationship and morphological characters, the species Acarella costaricensis and Perizomella inquinans are synonymised. We therefore transfer the genus Acarella (=Perizomella) to the family Vizellaceae whereby the asexual species exhibit ovoid to ellipsoidal or rarely subglobose, brown to dark brown, with transverse hyaline band, formed on phialidic, hyaline cells lining the inner cavity of the upper wall (Hyde et al. 2013).