Distinguished from all other species in the Hymenelia/Ionaspis complex by its minute apothecia (<0.1 mm diam.). Further characterized by the combination of a trebouxioid photobiont and apothecia with a granular ephymenium and lack of internal pigmentation or reaction with K or N.
Type: Falkland Islands, East Falkland: Estancia, SE side of inlet 6 km west of house, 51.657400°S, 58.262245°W, sea level, rocks at back of shore, 1 November 2015, Fryday 11254 (MSC—holotype).
Description
Thallus effuse, areolate, rarely rimose, pale cream to orange-pink; areoles contiguous or dispersed, orbicular when dispersed, 0.15–0.3 mm diam., irregular and larger when contiguous, 0.3–0.5 mm across; medulla I–. Photobiont trebouxioid; cells 6–12 µm diam.
Apothecia frequent, arising singly from the centre of each areole, pale pink (rarely hyaline), 0.06–0.1 mm diam.; concave to flat; margin not apparent. In section:proper exciple poorly developed, hyaline. Hymenium 85–100 µm high; paraphyses simple, thin c. 1 µm wide, not swollen at the apices; epihymenium not pigmented but with numerous small brownish granules not dissolving in K or N. Hypothecium hyaline, 12–15 µm high, composed of randomly orientated hyphae. Asci cylindrical, c. 50 × 15 µm, “Hymenelia”-type (outer coat I+ blue but inner walls and apical dome K/I–); ascospores simple, hyaline, (11–)12.50±0.80(–14) × (6–)6.67±0.78(–8) µm, l/b ratio (1.625–)1.89±0.19(–2.17) (n = 12).
Conidiomata not observed.
Chemistry. no lichen substances detected.
Etymology. The name refers to the minute size of the apothecia.
Distribution and Ecology: Known only from the Falkland Islands. Apparently quite frequent, but easily overlooked because of the small size of the immersed apothecia. Known from four localities on East Falkland, all close to the sea. Associated species: Buellia sp., Lecidea sp., Porina austroatlantica P. M. McCarthy & Fryday, Porpidia cf. crustulata (Ach.) Hertel & Knoph, P. sp., Rhizocarpon malvinae, R. infernulum (Nyl.) Lynge, Rinodina cf. peloleuca (Nyl.) Müll. Arg., Verrucaria s. lat. sp.