Acarospora malouina Øvstedal & Knudsen
in Øvstedal et al.,Phytotaxa 340 (1): 88–89. 2018.
Thallus of contiguous squamules, 0.3–3 cm in diameter, 300–560 μm thick, indeterminate; squamules up to 2 mm wide, rugulose, fissured, continuously dividing. often forming large clusters of small squamules with 1 or 2 apothecia; upper surface glossy yellow, lower surface pale brown with a central stipe; epicortex thin, less than 10 μm thick or almost absent, of gelatinized thin hyphae, cortex red-brown throughout, 20–60 μm thick, cells usually 2–4 μm wide, angular to round; algal layer uneven, interrupted by hyphal bundles 10–60 μm wide, forming algal palisades, 150–200 μm thick, algal cells 8–12 μm wide; medulla obscure, white to brownish, 200–300 μm thick of conglutinated anticlinal hyphae mostly 1–2 μm wide, continuous with stipe.
Apothecia 1–10 per squamule, disc reddish-brown, epruinose, 0.1– 0.4 mm wide, with or without a distinct parathecial ring, same color as the thallus or reddish brown, darker than disc; parathecium 10–100 μm wide at surface of disc, intergrading with cortex. Layer between parathecium and hymenium I+ blue, up to two thirds of distance to disc (referred to as an abscission layer in Castello & Nimis 1994); epihymenium ca. 20–25 μm, yellowish-brown, with thin hyaline gelatinous upper layer; hymenium 200–250 μm tall, hyaline I+ blue turning red, paraphyses thin, 1–1.5(–2.0) μm wide, apices not expanded, some branching; asci 100–150 × 15–30 μm, hundreds of ascospores, ellipsoid, 2.5–3.0 × 1.5–2.0 μm; subhymenium 20–30 μm tall, I+ blue; hypothecium 20–30 μm tall, I–.
Pycnidia not observed, but apothecial initials abundant.
Chemistry: rhizocarpic acid by tlc.
Distribution and Habitat:
The new species is known only from the upper surface of low siliceous rocks (quartz sandstone), close to penguin rookeries on the north shore of Saunders Island, north of West Falkland.