Racodiaceae Link, Abh. Dt. Akad. Wiss. Berlin: 166 (1826) .
MycoBank number: MB 81239; Index Fungorum number: IF 81239; Facesoffungi number: FoF 06304, 44 species.
On inclined to vertical siliceous rocks in recesses. Hyphae vertically arranged, lacking interlocking corrugations, lacking lateral spines, thick-walled, fused to form elongated rectangular cells, vertically orientated cells along the axis of the algal filament, overall smooth, rather than a knobby appearance, completely smooth in SEM.
Type – Racodium Fr.
Notes – Racodiaceae was introduced with a single genus. Members of this family are found on inclined to vertical siliceous rocks in recesses where it is cool with no direct rain, but high humidity, and with a temperate/subboreal distribution (Hawksworth et al. 2011, Nimis et al. 2018). Phylogenetic analyses based on the type species Racodium rupestre showed that it forms a distinct clade as genus incertae sedis in Capnodiales (Muggia et al. 2008), and the same result was shown by Crous et al. (2009c) and Ruibal et al. (2009). Racodiaceae was mentioned again to accommodate Racodium in Lücking et al. (2017) and Wijayawardene et al. (2017a). This family is poorly studied. We provide a drawing to show its morphology (Fig. 22).
Figure 22 – Racodium rupestre (redrawn from Hawksworth et al. 2011). a Filament. b SEM micrographs of filaments. Scale bars: a = 10 μm, b = 2 μm.