Flora of New Zealand Series

≡Arthonia suffusa C.Knight, Trans. N. Z. Inst. 15: 353 (1883).

Holotype: New Zealand. Sine loco [probably Wellington], 23.xi.77, Charles Knight – WELT, Herb. Knight Vol. 63A, p. 3. 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 lectoptype [fide Galloway (1985a: 20)], but this must now properly be regarded as isotype.

Description : Flora (1985: 20).

N: Known only from the type collection, but probably more widely distributed on rimu bark.

Endemic

Illustration : Knight (1883: pl. XXXV, fig. 4 – as Arthonia suffusa).

Arthothelium suffusum is characterised by: the corticolous habit; a grey-white, minutely pruinose, areolate thallus delimited by an irregular marginal, black prothalline line; minutely warted-wrinkled areolae; minute, black apothecia, 0.1–0.3(–0.5) mm diam., that are often white-pruinose; epithecium brown-black, 13–30 μm thick; pale-yellow to hyaline hymenium, 90–100 μm tall; hypothecium pale-yellow; and colourless, ovoid to oblong ascospores with 3–9 transverse septa and 1–3 vertical septa, 20–30(–33) × 13–16.5 μm, without an enlarged terminal cell.