Coccocarpia melloniorum

The thallus of Coccocarpia melloniorum is epiphyllous (growing on leaves) and microfoliose, with a rounded to irregular outline and diameter ranging from 5–15 mm. Its lobes are thin, flat, linear to flabellate, and 0.3–0.6 mm wide, widening to 0.5–1.0 mm at the tips. The upper surface of the lobes is blue-grey but may show brown discolouration in some specimens, with indistinct pale grooves visible under high magnification, particularly at the tips of the lobe. The lower surface is pale to dark brown, with numerous black, branched rhizines measuring 0.3–0.5 mm long.^[2]

Coccocarpia melloniorum is distinguished from similar species by its numerous squamiform isidia, which are mostly laminal, rounded, and sometimes irregular or elongate. These isidia are 0.05–0.20 mm in diameter and up to 0.3–0.5 mm long when elongated. No apothecia have been observed, and no substances were detected by thin-layer chromatography.^[2]

Coccocarpia melloniorum shares similarities with the neotropical Coccocarpia neglecta, but the former has wider thallus lobes and squamiform isidia. Coccocarpia melloniorum also resembles Coccocarpia dissecta, which has isidiate lobes and black rhizines. However, C. dissecta has cylindrical isidia and a more robust appearance with closely adjacent lobes. The lobe morphology of C. melloniorum is intermediate between that of C. neglecta and C. epiphylla, with the latter lacking isidia and having broader, contiguous thallus lobes and a pale underside with pale rhizines.^[2]

Coccocarpia melloniorum is found in the Philippines, specifically in Tayabas, Luzon, on Mt. Binuang. It grows on the leaves of unidentified dicotyledon plants.^[2]