Flora of New Zealand Series

≡Arthonia spadicea C. Knight, Trans. N. Z. Inst. 15: 353 (1883) non Leight [Ann. Mag. nat. Hist., ser. 2, 13: 442 (1854)].

Holotype: New Zealand. Sine loco [probably Wellington], 11.xi.77, Charles Knight – WELT – Herb Knight Vol. 63A, p.1. This material has drawings of asci, ascospores and a section of the apothecium made by Knight, and used for the engravings illustrating the type description. Knight material from the BM was earlier chosen as lectotype [fide Galloway (1985a: 20)], but this must now properly be regarded as isotype.

Description : Flora (1985: 19–20 – as Arthothelium spadiceum).

N: Known only from the type collection.

Endemic

Illustration : Knight (1883: pl. XXXV, fig. 3 – as Arthonia spadicea).

Arthothelium spadiceum is characterised by: the corticolous habit; a glaucous to grey-white, roughened to arachnoid thallus, delimited by a thin, black prothalline line; innate rounded to oblong, pale red-brown to yellow-brown apothecia (disc granular K+ purple); epithecium brown to 40 μm thick; hymenium pale brownish yellow to hyaline, 65–120 μm tall; a colourless hypothecium; ascipyriform, bitunicate, pedicellate, 65–95 × 50–60 μm; and brownish, ovate to oblong ascospores; with 4–10 transverse septa and 1–5 vertical septa, 33–46 × 13–25 μm, without an enlarged terminal cell.