Flora of New Zealand Series

Holotype: New Zealand. South I., Westland: Fantail Falls Track, by Haast River, on smooth, water-worn rocks, 480 m, 1.vii.1999, A. Knight s.n. – OTA 057850. Isotype – CHR 533988.

Description : Thallus very closely attached to substratum, orbicular to irregularly spreading, 2–5(–7) cm diam., prominently delimited by a generally persistent, marginal, fringe-like prothallus, dark chestnut-brown, fibrous when moist, pale-brownish, shining, varnish-like when dry, 3–6 mm wide. Upper surface minutely areolate, of very small round to subirregular, convex, densely congested papillae, 0.1–0.4(–1) mm diam., areolae commonly widely separated on underlying prothallus near margins, crowded centrally, lettuce-green to olive-green when moist, most noticeably in a marginal zone 5–10 mm wide, becoming darker olive to fawnish centrally, dirty brownish when dry, the tops of papillae markedly pale, often white-pruinose (×10 lens), and frequently with a central pycnidium, the pore releasing a blob of pinkish gel when moist (×10 lens), without maculae or pseudocyphellae. Medulla white. Photobiont green, chlorococcoid, cells globose, 8–10 μm diam. Cephalodia round to irregular, 0.1–1(–2 rarely to 6) mm diam., [large, over-mature cephalodia secondarily colonised by thalline papillae] commonly best developed in a zone free of apothecia towards margins, initially level with, or projecting only slightly above, surface of papillae, at length ±superficial, spreading over tops of papillae and readily detached, translucent, pale-brownish to dark purplish brown to black when moist, pale-greyish to brownish and opaque when dry, the surface irregularly furrowed to verrucose, epruinose; cyanobiont Scytonema, in chains, cells compressed, cylindrical to fabiform, 10–12.5 μm diam. Apothecia central, scattered to crowded, round, 0.5–1(1.5) mm diam., solitary or in groups of 2 or 3, sessile, constricted at base, disc convex, pale to dark carmine-red, matt, epruinose, translucent when moist, darkening to red-brown or brown-black when dry, occasionally fissured in mature fruits. Thalline exciple thin (0.01 mm wide or less), entire, smooth or very minutely crenulate (×10 lens), concolorous with thallus to pale-whitish, persistent or becoming occluded at maturity. Proper margin very thin, visible as a slightly elevated rim to disc, concolorous with or slightly paler than disc. Epithecium granular yellow-brown to olivaceous, 25–35 μm thick, unchanged in K. Hymenium colourless to very pale pinkish, not inspersed with oil droplets, 160–180 μm tall. Paraphyses very slender, unbranched, to 1.5 μm wide, not noticeably swollen at apices. Hypothecium yellow-brown in upper parts, darkening to red-brown below (unchanged in K), densely interwoven, 150–170 μm thick. Asci 8-spored, narrowly clavate, tapering at foot, 150–170 × 10–13.5 μm. Ascospores uniseriate or partly biseriate in ascus, simple, colourless, contents not granular or guttulate, narrowly ellipsoidal, apices pointed, (25–)27–32(–33.5) × 5–6 μm, smooth walled. Pycnidia frequent, 1 per areole; ostiole central, pale red-brown, minute, projecting slightly from surface. Conidia filiform, slightly curved, 15–20 × 0.5 μm.

Chemistry : Thallus K−, C+ red, KC+ red, Pd−; containing gyrophoric acid (major), 5- O -methylhiascic acid (major), lecanoric acid (minor), and 5-methoxylecanoric acid (minor).

S: Nelson (Springs Junction), Westland (Fox Glacier, Haast River), Canterbury (Bealey River, Hawdon River, Havelock River), Otago (Hunter Valley, Kinloch–Routeburn Road, Scott Creek).

Endemic

Illustrations : Galloway (2004a: 149, fig. 1); Johnson (2005: 30, fig. 1).

Placopsis hertelii is characterised by: a closely attached, orbicular thallus delimited at the margins by a prominent, fibrous, brown to brown-black prothallus, best developed in specimens attached to rocks and pebbles and extending to 6 mm beyond the lichenised thallus margin; a minutely areolate upper surface, the areolae of densely congested minute papillae, often widely scattered on the prothallus near the margins, becoming crowded centrally; scattered, sessile cephalodia; small, sessile apothecia constricted at base, to 1.5 mm diam., with a carmine-red, epruinose disc when moist, brown-black when dry, with whitish entire to crenulate margins; a yellow-brown to red-brown hypothecium; very narrowly clavate asci; and narrowly ellipsoidal to acicular ascospores with pointed apices, (25–)27–32(–33.5) × 5–6 μm.