Flora of New Zealand Series

=Verrucaria retrospiciens Stirt., Proc. phil. Soc. Glasgow 10: 302 (1877).

≡Porina retrospiciens (Stirt.) Müll.Arg., Bull. Herb. Boissier 2, App. 1: 91 (1894).

≡Segestria retrospiciens (Stirt.) Hellb., Bih. K. Sv. Vret.-Akad. Handl. 21 (3/13): 132 (1896).

=Ascidium fusiforme C.Knight, Trans. N. Z. Inst. 15: 354 (1883).

Ascidium fusiforme. Holotype. New Zealand. Sine loco [probably Wellington], Charles Knight – WELT.

Description : Thallus corticolous, continuous to extensively cracked, pale grey-brown, pale yellow-brown or pale greyish green, matt to slightly glossy, smooth to verruculose, corticate or with simple to branched isidioid outgrowths. Perithecia hemispherical to subglobose, 0.36–0.76 mm diam., apex concolorous with thallus to medium-brown, ostiole inconspicuous or in a shallow depression. Involucrellum apical to dimidiate or extending to exciple base level, yellow-brown to orange-brown. Exciple pale yellow-brown, 15–25 μm thick. Asci elongate-cylindrical, 140–200 × 20–30 μm. Ascospores fusiform to broadly fusiform, (6–)7(–9)-septate, 35–65 (–90) × 10–18(–20) μm, halonate.

N: Wellington. On tree bark, collected by John Buchanan (Stirton 1877: 302). A widely distributed tropical species. A detailed geographical distribution of this species (plus map) is given in McCarthy (2003d: 73–74; 74, fig. 7).

Pantropical

Illustrations : Knight (1883: pl. XXXVII, fig. 20 – as Ascidium fusiforme); McCarthy (1994a : 401, fig. 4A) ; Lücking & Vězda (1998: 195, fig. 3F; 202, fig. 7C).

Verrucaria retrospiciens. Type: New Zealand. Near Wellington, John Buchanan – not seen [no authentic material located in GLAM, BM or WELT]. Stirton (1877: 302) remarks of this species: "The species of this section of Verrucaria appear to be prevalent near Wellington, and assume a more luxurious habit than elsewhere. The present is intermediate between V. nucula and mastoidea. The pale epithecium allies it to the former, while the larger spores and broad halo would lead one to refer it to the latter. Three, viz., V. mastoidea, V. nucula, and V. desquamescens, found in New Zealand, do not preserve any fixed or definite characters, but assume those of one another almost indiscriminately. The present is separated meanwhile, until a wider range of examples shall have definitely settled the question of specific distinction."

Porina nucula is characterised by: the corticolous habit; the rather large, hemispherical to subglobose perithecia that are concolorous with the thallus; and the large, 7-septate, halonate ascospores, 35–65(–90) × 10–18(–20) μm.