Flora of New Zealand Series

≡Thelotrema macrocarpum C.W.Dodge, Nova Hedwigia 19: 457 (1971) ["1970"].

=Chroodiscus australis Kantvilas & Vězda, Lichenologist 32 (4): 331 (2000).

Thelotrema macrocarpum. Holotype: New Zealand. Auckland Is, Ewing I. on rata bark, 17.i.1966, B.A. Fineran 1434b – CANU.

Description : Thallus spreading to 7 cm diam., thin, effuse, patchy to lacking, 75–120 μm thick, pale greyish to olive-buff, somewhat gelatinous and translucent when moist, reflecting surface texture of substratum; prothallus and cortex not developed. Photobiont green, ? Trentepohlia. Apothecia sessile, constricted at base, scattered to somewhat crowded, at first enclosed in subglobose, cracked and sculptured thalline warts, 0.5–1.5(–2) mm diam., appearing perithecioid at first, disc orange-brown to olive-brown, concave to plane, smooth, glossy, epruinose, typically mostly obscured by inrolled exciple; thalline margin and proper margin whitish to pale-brown, Geaster- like, at first incurved and entirely obscuring disc, becoming radially fissured (generally with 3–4 deep cracks), dentate then tangentially lamellate, exfoliating, abraded and somewhat white-pruinose, but nearly always partly obscuring disc. Hymenium hyaline, to 220 μm tall. Hypothecium pale yellowish, K+ orange, 120–220 μm thick. Paraphyses simple, straight, 1.5–2 μm thick. Asci cylindrical, monosporous, 150–180 × 30–40 μm. Ascospores broadly ellipsoidal, hyaline, straight, thin-walled, non-halonate, I−, 165–175 × 25–33 μm, very densely muriform.

Chemistry : Thallus K+ brownish red, C−, KC+ red, Pd + yellow; containing stictic acid (major), constictic, cryptostictic (tr.) and connorstictic (tr.) acids.

St: (Port Pegasus). A: (Ewing I.). C: Amongst bryophytes on bark, and overgrowing peat and decaying vegetation on roots of southern rata (Metrosideros umbellata), rarely on old tree-fern trunks. Known also from Staten Island (Argentina) and the Falkland Is where it occurs on peaty soil and over bryophytes (Kantvilas & Vězda 2000). Tasmanian material with smaller ascospores, and 2–4 or rarely 6-spored or 8-spored asci, is referred to ssp. tasmanicus (Kantvilas & Vězda 2000: 334–336).

Austral

Illustration : Kantvilas & Vězda (2000: 333, fig. 3).

Chroodiscus macrocarpus is characterised by: the corticolous/muscicolous, terricolous habit; the characteristic Geaster -like apothecia; monosporous asci; very large, muriform ascospores, 70–150 × 26–45 μm; and with stictic and cryptostictic (tr.) acids in the medulla.