Tapellaria granulosa

The thallus (lichen body) is corticolous (growing on bark) and forms a continuous crust 2–5  cm across and about 30–50 micrometers (μm) thick. Its surface is pale green and densely granulose, giving it an isidia-like ("isidiate") appearance. The granules are described as clusters of photobiont cells wrapped in fungal hyphee; the photobiont is chlorococcoid (a green alga). The apothecia are sessile (sitting directly on the thallus), rounded to irregular, and 0.5–1 mm in diameter (180–270 μm high). The disk is initially flat but becomes convex with age; it is black to brownish black, with a thin, persistent black margin. Under the microscope, the paraphyses are branched and anastomosing (net-like). The asci (spore sacs) measure about 90–120 × 18–28 μm and contain 4–8 ellipsoid, muriform ascospores. The spores measure about 20–25 × 10–15 μm and have 3–5 transverse septa and 1–2 longitudinal septa per segment. Campylidia (asexual spore-producing structures) are also present (0.4–0.6 mm broad and 0.7–1 mm long). They produce filiform (thread-like), curved conidia (asexual spores) that are 5–7-septate and about 40–50 × 2 μm. No lichen substances were detected by thin-layer chromatography.^[1]

The species was originally known from two collections from Fakahatchee Strand Preserve State Park, where it grows on the bark of Taxodium. It was treated as closely related to Tapellaria malmei from the same locality, sharing similarly small muriform ascospores (4–8 per ascus) but differing in its distinctive granular thallus. The granules were interpreted as unlikely to function as true isidia and may instead increase thallus surface area. Similar between-species variation in thallus texture has been compared with patterns reported in the related genus Lasioloma.^[1] Tapellaria granulosa has also been documented from Santa Cruz Island in the Galápagos.^[2]