Galapagos Species Database

Thallus crustose, superficial, felty, pale greyish or rarely creamy or bluish white, ecorticate, thin, up to 0.3 mm thick; hyphae irregularly branched, hyaline, mainly 1.5–2 m diam., forming numerous convex to subglobose sporodochia 0.4–1 mm diam. which are white, cream or sometimes with a pinkish or orange tinge, usually fading to white in the herbarium. Sporodochial conidia hyaline, smooth to slightly roughened, 0–1-septate, with rounded or truncate apices, simple conidia ellipsoid to oblong, rarely spherical, (4–)4.5–6.5(–8) × (3–)3–4(–5), l/b ratio 1.3–1.9 (n = 60), 1–septate conidia often distinctly constricted at the septum, (6–)7– 11.5(–15) × (3–)3.5–4.5(–5) µm, l/b ratio 1.9–2.9 (n = 70) (for a detailed description of the conidiogenesis see Hawksworth et al. 1979). Prothallus brown, byssoid, 1–4(–5) mm wide. Photobiont Trentepohlia. Ascomata very rare, sessile, short cylindrical to conical, 0.5–1 mm diam., 0.4–0.6 mm high (excluding the mass of ascospores), 1–1.5(–2) times as wide as high. Thalline margin well-developed, c. 50–60 µm wide, approx. half the height of the ascomata, densely inspersed with minute colourless crystals dissolving in K (observed in polarized light), of hyaline hyphae 1.5–2 mdiam. Excipulum 10–25 µm laterally, sometimes thinner or absent below, of dark brown, sparingly branched and interwoven hyphae, 1.5–2 µm in diam. Mazaedium well-developed, black, sometimes only slightly projecting over the thalline margin but often extending further. Paraphyses branched, anastomosing, 1.5 µm wide. Asci dissolving at early stages, cylindrical, with eight uniseriate ascospores, 35–45 × 4–5 µm. Ascospores 1-septate, dark brown, with a heavily pigmented band around the central part, ellipsoid, sometimes constricted at the septum, occasionally with slightly pointed ends, wall thick, (9–)10.5–13.5(–17) × (5.5–)6.5–8.0(–9) µm, l/b ratio 1.4–1.8 (n = 110). Pycnidia rare (only observed in Smith T904), present at the margin of the thallus, immersed, visible as brownish spots of c. 0.15–0.3 mm, surrounded by a white thalline margin of c. 50–80 m thick; pycnidial wall very reduced; pycnoconidia filiform, straight or slightly curved, hyaline, 9–14 × 1 µm. Chemistry. Thallus (incl. margin of ascomata) C+ weakly red, K−, KC+ red, P−, UV− or UV+ orange. Sporodochia C+ red, K+ yellow, KC+ red, P−, UV− or UV+ orange. TLC: lecanoric acid in all specimens examined; in addition, lichexanthone is present in Ertz 11546, 14915 and 14898, the last two having an obvious UV+ orange thallus; trace of a fatty acid in Diederich 16335.

Hawksworth et al. (1979) suggested that Tylophoron hibernicum starts as a lichenicolous species overgrowing other lichens, taking over their algae, and eventually developing an independent thallus. All specimens collected by us have large thalli, and therefore we could not confirm that they started growth as a lichenicolous fungus. Tylophoron hibernicum differs from other known Tylophoron species by wider ascospores and, when ascomata are lacking, by a thin, bright to pale greyish or bluish white thallus with a felty surface.