Flora of New Zealand Series

Description : Thallus dark-brown to black, filamentous, forming small, felt-like mats. Hyphae 4–7 per photobiont filament, c. 1 μm thick, straight, parallel, unbranched, closely investing photobiont filaments. Photobiont Trentepohlia, forming long chains.

S: Westland (Paringa River), Otago (Routeburn Track, Horse Ra.). On vertical or overhanging rock faces, and on damp rocks in riverbeds, often with species of Placopsis. First collected in New Zealand by Prof. Volkmar Wirth (Wirth 1997: 12). Still very poorly known in New Zealand and probably overlooked in cool, damp environments. In the Northern Hemisphere Racodium rupestre frequently associates with Cystocoleus ebeneus and species of Lepraria. Known also from Great Britain, Europe, Scandinavia, North America and Tasmania (Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Goward 1999; Brodo et al. 2001; Coppins 2002b; Kantvilas 2002b; McCarthy 2003c, 2006; Nimis & Martellos 2003; Santesson et al. 2004).

Bipolar

Illustrations : Dobson (1992: 291; 2000: 334; 2005: 380); Purvis et al. (1992: 229, fig. 13B); Wirth (1995a: 288, pl. 37B); Goward (1999: 206); Brodo et al. (2001: 620); Kantvilas (2002b: 67, fig. 1B); Sérusiaux et al. (2004: 75).

Racodium rupestre is characterised by: the straight, longitudinally arranged hyphae that closely invest the single, central filament of Trentepohlia (use compound microscope). It is closely similar to Cystocoleus ebeneus (q.v.), but is distinguished from it by the straight fungal hyphae; in Cystocoleus they are contorted.