Flora of New Zealand Series

≡Arthonia cinerascens var. crustosa Stirt., Proc. phil. Soc. Glasgow 10: 306 (1877).

Lectotype: New Zealand. Near Wellington, J. Buchanan – GLAM NHB-1927-8-1725 [fide Galloway (1985a: 20)].

Description : Flora (1985: 20).

N: Wellington, on bark of Dacrydium cupressinum.

Endemic

Arthothelium stirtianum is characterised by: the corticolous habit; the pale glaucous-grey to off-white, areolate, smoothly ivory-like to minutely scurfy thallus delimited by a thin, black prothalline line; black, subglobose to innate apothecia, 0.1–0.6 mm diam.; 2-spored asci; and colourless to brown, ellipsoidal to oblong muriform ascospores, 30–40 × 12–20 μm, without an enlarged terminal cell. Stirton has noted on the type. "The epithecium forms an almost continuous black covering which is liable to crack as in the Verrucariae".