Flavoplaca arcisproxima

The thallus of Flavoplaca arcisproxima is coloured yellow to yellow-orange, comprising solitary or rarely aggregated, somewhat umbilicate squamules. These squamules are flat, smooth, and have margins divided into minute lobes. They are typically 80 to 240 μm thick and 0.44 to 1.18 mm wide. The marginal soralia are of the confusa or flavocitrina type, with soredia or blastidia measuring between 25 and 86 μm in diameter. The species lacks a distinct cortex, but has an alveolate (honeycombed) cortex with a thickness ranging from 8 to 46 μm.^[2]

Apothecia were absent in the initial specimens of Flavoplaca arcisproxima investigated.^[2] They were found in some specimens collected in Ukraine.^[4] Conidia are quite small, with measurements ranging from 2.5 to 4.0 μm in length and 0.5 to 1.5 μm in width.^[2]

Flavoplaca arcisproxima is known from maritime sites, usually in the supralittoral zone. It prefers base-rich, hard siliceous rocks, such as diabase, and can also be found on lime-rich claystone. The species is found accompanying several other lichen species, including Caloplaca cf. aegea, Calogaya biatorina, Caloplaca aff. furax, Kuettlingeria teicholyta, Candelariella plumbea, C. vitellina, Catillaria chalybeia, Diplotomma alboatrum, Polyozosia albescens, Polyozosia dispersa, Phaeophyscia orbicularis, Verrucaria macrostoma f. furfuracea, and Xanthoria cf. calcicola. The species is known from the Black Sea region of the Crimean Peninsula and Crete in the eastern Mediterranean.^[2]