Polycoccum anatolicum is a minute fungus that parasitises lichens without killing the host tissue outright. Its own vegetative filaments (hyphae) are colourless and extremely thin, and the only obvious sign of infection is a gradual bleaching of the colonised patches of thallus. The spore-bearing structures are tiny, flask-shaped perithecia that develop one at a time. When young they lie buried in the host, with just the pore (ostiole) peeping out; at maturity they rise slightly above the surface and measure 75–90 micrometres (μm) across. Each perithecial wall is 10–15 μm thick, built from several layers of tightly packed reddish-brown cells arranged like bricks (a textura angularis), and it darkens towards the top.[2]
Inside, a mesh of slender, septate filaments (pseudoparaphyses) threads the cavity. The asci arise from the base of the perithecium; they are double-walled (bitunicate), narrowly cylindrical to club-shaped, and bear eight ascospores. Mature asci are typically 83–91 × 14–18 μm, with a thickened tip and a dextrinoid (reddish-brown) inner contents when stained in iodine. The spores line up in a single row, each one shaped rather like the sole of a shoe, with rounded ends and a single, barely constricted cross-wall. They are pale brown at first, then darken and become finely warty; older spores often contain several oil droplets. Typical dimensions are 26–30 × 9–11 μm. No asexual reproductive bodies (conidiomata) have been observed, and chemical spot tests show no amyloid reaction in the hymenial gel.[2]
Polycoccum dzieduszyckii is morphologically similar, but can be distinguished from P. anatolicum by its eight-spored asci and its growth on Verrucaria.[2]
