Flora of New Zealand Series

P. hookeri (Church. Bab.) D. Galloway et P. James, Lichenologist 12: 299 (1980).

Sticta hookeri Church. Bab., Fl. N.Z. 2: 282, pl. CXXV B, (1855).

Lectotype [fide Galloway and James loc. cit., p. 299 (1980)]: New Zealand. Bay of Islands, J.D. Hooker, BM!

Thallus ± orbicular, 5-10(-15) cm diam., ± loosely attached, margins ± free. Lobes broadly laciniate or ± rounded, 10-20 diam., margins entire or variously notched or incised. Upper surface slate-blue to brownish-black, conspicuously white-maculate (×10 lens) when wet, conspicuously and often densely reticulate-faveolate, ridges pale (free of algae), smooth or sharp, faveolations deep, matt or glossy, smooth or wrinkled, often suffused brownish centrally, without isidia, soredia or pseudocyphellae. Medulla white. Photobiont blue- green. Lower surface pale buff or whitish with a ± uniform, short, stiff, brownish tomentum, tomentum in short, discrete bundles, wrinkled-bullate, glabrous at margins. Pseudocyphellae white, frequent, raised, verruciform, with a naked, white, waxy margin, 0.05-0.2 mm wide, exposed hyphae in small, punctiform depression. Apothecia ± frequent, sessile to subpedicellate, 1-8 mm diam., concave to plane at first becoming irregularly convex with age, disc black, matt, epruinose, minutely granular, ± shining, margins pale, thin, inflexed, crenulate, thalline exciple concolorous with thallus, smooth or minutely verrucose. Ascospores oblong-ellipsoid, polaribilocular, brown, (20-)23-25(-30) × 8-11 µm. Chemistry: Cortex C+ red. Hopane-6α,7β,22-triol, tenuiorin, methyl evernate, methyl lecanorate, methyl gyrophorate, gyrophoric, stictic, norstictic and constictic acids.

N: North Auckland to Wellington. Throughout, primarily lowland in standing forest, forest remnants and on successional vegetation in humid habitats. S: Nelson (Lake Rotoroa).

Endemic

P. hookeri is a faveolate species with a blue-green photobiont. The upper cortex gives a C+ red reaction. It is related to P. montagnei and P. durietzii. It is distinguished from P. durietzii by the blue-green photobiont and the brown tomentum of the lower surface, however the two species are very closely related chemically and morphologically. Photosymbiodemes between P. hookeri and P. durietzii were discovered by Drs T.G.A. Green and A.L. Wilkins (Waikato University). P. montagnei differs in the closely appressed habit (P. hookeri is usually only attached centrally and is free and ± subascendent at margins) the pale buff, sparsely tomentose lower surface with pale yellowish, insignificant, sparse pseudocyphellae and also marginal and laminal phyllidia and phyllidiate apothecial margins.

P. hookeri is mainly a northern species and is only rarely collected in Nelson. It is characteristic of shaded, humid habitats and is often densely developed on regenerating Dacrycarpus dacrydioides twigs.

Discussing the species, Babington ( loc. cit., p. 282) states "... the plant is, after all, far more nearly allied to S. anthraspis Ach., which we refer to S. faveolata but the lobes are not, as it seems, corniculate, and the apothecia are much larger and more free. The apothecia are in their very infancy closed, but very soon become remarkably open and free, almost stipitate; the thalline excipulum (which is often corrugated outside) is polished towards the edge, and this is so extremely fine that the disc appears to have no distinct margin. The thallus also shows some slight symptoms of becoming isidiophorous, with sooty processes; but these do not assume a distinct coralline form, as in S. sylvatica. The upper and under lobes have a strong tendency to adhere to each other, so as to become absolutely united at certain points, and not to be separated without rupturing the thallus..." The plant is well illustrated by Walter Fitch (Babington loc. cit., pl. CXXV B).