Gyalideopsis lambinonii

Gyalideopsis lambinonii forms a thin, continuous bark-inhabiting thallus that is grey-whitish, smooth and somewhat glossy. It lacks a distinct prothallus and has a cartilaginous, hyaline (translucent) cortex. The photobiont layer is 25–35 μm thick, composed of roughly spherical to broadly ellipsoid algal cells about 8–10 μm in diameter. The thallus margin is lobulate to crenulate, and numerous hyphophores occur across the surface.^[2]

The hyphophores are distinctive: each consists of a short, relatively thick central stalk that supports a black, round, shield-like head 0.8–1 mm wide. In dry material, the shield margin is slightly incurved towards the thallus, while the centre is conspicuously depressed. From the transition zone between stalk and shield arise many hyaline hyphae, 5–6 μm thick, that branch into short stalks, each bearing a spherical hyphal tuft 50–70 μm across. These tufts comprise the diaspores; their hyphae, when rehydrated, separate into 30 μm-long, multicelled, strongly constricted elements, giving a beaded or "string-of-pearls" appearance.^[2]

Apothecia are infrequent. They are broadly adnate, 0.8–1 mm wide and 0.15–0.2 mm tall, remaining flat throughout development. Young apothecia may show a slightly raised, blue-white or very dark margin, but the margin soon becomes indistinct. The disc is dark brown to almost black, smooth, and in moist conditions becomes faintly translucent. The lateral excipulum (20–30 μm thick) is hyaline, shading to brown near the surface; the basal excipulum forms a hyaline ring 30–50 μm tall. The hypothecium is 10–15 μm thick and colourless. The hymenium reaches 80–90 μm in height, with an olivaceous epithecial zone; below this the tissue is hyaline. Paraphyses are dense, richly branched and anastomosing, with internal cavities (lumina) 0.5–0.8 μm wide. Asci are clavate, narrowing into a long stalk, and contain a single spore.^[2]

The ascospores are ellipsoid, straight, and conspicuously muriform, measuring 40–60 × 20–30 μm. They possess numerous transverse septa and additional longitudinal septa, and are strongly constricted at the septa.^[2]

Gyalideopsis lambinonii was originally described from high-elevation tropical forests in central Africa. It was collected on the bark of an Agauria tree at 2,640 m elevation on Kahuzi, in Kivu Province of Zaire, with a second collection from the same mountain at 2,990 m on a bamboo culm.^[2]

Additional material has been recorded from the Forêt de Rugege in Rwanda, where the species was found at 2,350 m on the trunk of Hagenia abyssinica along the road between Butare and Cyangugu. All reported African collections are corticolous or lignicolous on woody hosts or bamboo in montane forest between about 2,350 and 2,990 m.^[2] Other collections of the lichen have been reported from Bolivia,^[5] Brazil,^[6] Venezuela,^[7] Costa Rica,^[4] Taiwan,^[8] Thailand,^[9] Vietnam,^[10] and Florida.^[11]