Flora of New Zealand Series

≡Arthonia interveniens Nyl., Acta Soc. Sci. fenn. 7: 482 (1863).

=Arthonia infuscata Kremp., Verhandl. Zool.-bot. Ges. Wien 26: 450 (1876).

≡Arthothelium infuscatum (Kremp.) Müll.Arg., Bull. Herb. Boissier 2, App. 1: 84 (1894).

=Arthonia lecideoides C.Knight, Trans. N. Z. Inst. 15: 352 (1883) non Th.Fr. [Gen. Heterolich. eur. recog.: 97 (1861)].

≡Arthonia knightii Zahlbr., Cat. lich. univ. 2 (1): 58 (1922).

Arthonia infuscata. Holotype: New Zealand. ?Auckland, 1858, Charles Knight 276 – BM.

Arthonia lecideoides : Type: New Zealand. Sine loco [probably Wellington], Charles Knight – ? WELT.

Description : Thallus superficial, thin, smooth to slightly roughened, green-grey to ashy grey. Apothecia 0.4–0.8 mm diam., subimmersed to adnate, oblong to subirregular, scattered to 2–3-together in small groups; disc plane brown-black to black. Hymenium K+ olive. Asci ovoid-pyriform. Ascospores colourless, oblong-ovoid to oblong-fusiform, 5–7 transverse septa, 1-septate longitudinally, 20–32 × 7–10 μm, without an enlarged terminal cell.

N: Auckland. On smooth bark. Known also from North America (Nylander 1863; Tuckerman 1872; Esslinger & Egan 1995), Australia and Tasmania (Kantvilas 1990c; McCarthy 2003c).

?Pantropical

Illustration : Kantvilas (1990c: 21, fig. 1A).

Arthothelium interveniens is characterised by: the corticolous habit; a K+ olive hymenium; and by elongate-clavate ascospores, 22–35(–40) × 7–12(–14) μm, with (4–)5–7(–9) transverse septa and 0–1(–4) longitudinal septa.