Flora of New Zealand Series

O. prominula Knight et Mitten, Trans. Linn. Soc. Lond. 23: 102 (1860) non Chev. O. subdifficilis Nyl., Lich. N.Z.: 115 (1888).

O. prominuloides Zahlbr., Cat. lich. univ. 2: 231 (1924).

O. subdifficilis var. avicenniae Zahlbr., Denkschr. Akad. Wiss. Wien math.- naturwiss. Kl. 104: 260 (1941).

Lectotype (fide Hayward, 1977): New Zealand, sine loco. Charles Knight, 65A:1, WELT.

Thallus smooth, continuous, cream-white, thin, sometimes disappearing, corticolous. Lirellae slender, flexuous, crowded closely together, 0.5-4.0 × 0.2 mm, thalline margin absent, proper exciple black, nearly closed, base heavily carbonised, closed. Ascospores 4-6-locular, 3-6 × 12-20 µm. Chemistry: Nil.

N: Northland (Whangaroa Harbour, Poor Knights Is, Opua, Kawerua), Auckland (Rangitoto I.), Bay of Plenty (Great Mercury I.), Wellington (Orua River near Feilding). Coastal and lowland on both native (Avicennia), and introduced (Salix) trees.

Endemic