Menegazzia dielsii (Hillmann) R.Sant.
* Account prepared by P.W. James (BM).
Parmelia dielsii Hillmann, Feddes Repert.: 38 (1940).
Type: New Zealand. Canterbury, Broken River. On Nothofagus solandri var. cliffortioides. L. Diels, ?B (destroyed) - not seen.
Thallus closely attached forming irregular, complete or partial rosettes, or irregularly encircling twigs and small branches, to 15 cm diam., seldom exceeding 10 cm diam., sometimes coalescing to form extensive, spreading colonies, texture rather soft and pliable to ± rigid, corticolous. Lobes numerous, shortly radiating at outer edges, medium, rather uniform, 2.0-2.8 mm wide, ± distinct from margins to centre, or obliterated by numerous, overlapping secondary lobes, terminal lobes irregularly or subdichotomously branched, sometimes palmate, contiguous throughout or occasionally ± discrete towards edges of thallus, becoming laterally compressed, compacted and contorted especially at centre, margins entire, sinuous-contorted, almost zig-zag interlocked, with few, short, interstitial laterals throughout, or more rarely, developing numerous laterals, not or sparingly blackened, apices concolorous, not suffused brownish, hollow, lower side of internal cavity white or grey. Upper surface uneven but mainly convex, pale grey, emaculate, smooth, even or commonly rugose-uneven, rarely transversely ridged, ± shining, without isidia or soredia. Perforations few to frequent, median, mainly on main lobes, 0.5-1(-1.5) mm diam., rounded or elliptical, rather variable, either gaping with a depressed margin (pertransita -type), or ± elevated not conical. Apothecia common, scattered or 2-3-contiguous, or sometimes clustered, sessile to shortly pedicellate, cupuliform to ± plane, margins regular to angular, thin, even, or thick, subcrenate, smooth or striate-lacerate, ± shining, naked or matt and ± white-pruinose, disc concave, brown or red-brown, ± densely white-pruinose, rarely ± glabrous. Epithecium dull brown, ± red-brown or colourless, densely granular, granules minute, forming an encrusting layer but not penetrating deeply into hymenium below. Hymenium 130-160 µm tall. Asci 8-spored, ovoid to turbinate, sometimes ± abruptly truncate towards apex, 85-95 × 38-41 µm. Ascospores ellipsoid or oval, 30-39(-42) × 20-23(-26) µm, wall 2 µm thick. Chemistry: Atranorin (cortex), psoromic, conpsoromic and echinocarpic ± acids, medulla K+ yellow, C-, KC-, Pd+ orange.
N: S of lat. 38°S (Lake Waikaremoana). S: Nelson to Fiordland (east and west of Main Divide), coastal Otago. St: (Mt Anglem, Glory Cove). On beech bark in beech forest and on subalpine scrub.
Endemic
M. dielsii is the only species of the genus in New Zealand with pruinose apothecial discs. Occasionally the pruina is poorly developed but is usually present on the discs of young apothecia. It is also the only species of the genus in New Zealand to contain psoromic acid. Echinocarpic acid is additionally present only in a small number of specimens. The epithecium is densely granular as in M. lucens; the UV- medulla and 8-spored asci separate it from this species.
