Cookellaceae Höhn.ex Saccardo & Trotter, in Saccardo, Syll. Fung. (Abellini) 22: 585 (1913).

MycoBank number: MB 80637; Index Fungorum number: IF 80637; Facesoffungi number: FoF 07870, 6 species.

Parasitic (or epiphytic) on leaves in terrestrial habitats, some possibly fungicolous. Sexual morph: Ascostromata superficial, subglobose or irregular, pulvinate to effuse, cushion-shaped, surface rough, flat or applanate at the base, scattered, pigmented, containing locules with individual asci, apapillate, opening by breaks in the upper surface; soft textured, cells of ascostromata comprising textura angularis to subglobulosa, with a basal hypostroma, developing in the host tissue, appearing as stromal blocks and swollen cells, of compressed packages of textura angularis to prismatica. Locules scattered throughout ascostromata, small, globose to subglobose, containing single asci, wall not obvious. Hamathecium lacking pseudoparaphyses. Asci 8-spored, bitunicate, fissitunicate, globose to subglobose or saccate, apedicellate, lacking an ocular chamber. Ascospores scattered in 3–5-seriate overlapping rows, muriform, ellip- soid to oblong, hyaline when immature, becoming brown at maturity, straight to slightly curved, ends rounded, with 3-transverse septa and 1-longitudinal septum in each cell, constricted at the septa, smooth-walled. Asexual morph: Coelomycetous, in genus Stigmella.

Type: Cookella Sacc.

Notes: The family includes only two genera Cookella and Pycnoderma (Wijayawardene et al. 2018), while Uleomyces was transferred to Myriangiaceae by Boonmee et al. (2017). Cookellaceae is treated in Dothideomycetes as family incertae sedis (Wijayawardene et al. 2018). The family is parasitic or epiphytic on leaves of dicotyledons and monocotyledons, with cushion-shaped to irregular thyriothecial single to multiloculate, ascostromata or ascomata, absent of pseudoparaphyses, 8-spored, bitunicate asci and muriform, light to dark pigmented ascospores (Hyde et al. 2013). The family lacks molecular data to establish its phylogenetic placement, especially as the type species is yet to be sequenced and there are no additional new taxa in this family.