Calvitimela austrochilenis is a crustose lichen with a creamy-white to yellow thallus that spreads widely and has a distinct margin. The thallus is relatively thick, measuring 0.5–1.5 mm, and features a thin bluish-grey prothallus at its edges. Its surface is cracked into small, flat areoles that are smooth and measure 0.3–0.5 mm across. Unlike some lichens, it lacks a protective outer cortex but contains pale brown pigmentation in its surface cells. The medulla, or inner fungal layer, contains large, insoluble crystals measuring 15–35 μm in diameter. The lichen's photosynthetic partner is a chlorococcoid green alga, with individual cells measuring 12–15 μm in diameter.[2]
The apothecia (fruiting bodies) are embedded within the thallus and appear as small, blue-black discs that are typically round but may have slight irregularities. They range from 0.2 to 0.4 mm in diameter and have a concave surface. A narrow crack usually separates the apothecium from the surrounding thallus, though in some cases, remnants of the thallus adhere to it, forming a pseudothalline margin. The proper margin of the apothecium is usually indistinct, but when visible, it appears as a thin, slightly raised edge. The blue-black pigment within the apothecia sometimes extends patchily into the surrounding thallus.[2]
Microscopically, the hymenium, the layer where spores develop, is 80–90 μm tall and contains scattered granules. The paraphyses—thin, thread-like structures that support the developing spores—are septate, occasionally branching and reconnecting, with a gelatinous sheath around 3 μm thick. Their tips are swollen to 5–8 μm in diameter. The epihymenium, the uppermost layer of the hymenium, is blue-black and reacts with chemical tests (H+ blue, N+ red) to produce a cinereorufa-green colouration. The hypothecium, the tissue beneath the hymenium, is thick (approximately 300 μm), and though it is inherently colourless, it appears pale brown due to the presence of minute crystals that dissolve in potassium hydroxide solution (K).[2]
The lichen produces cylindrical, Lecanora-type asci measuring 60–70 by 15–17 μm, each containing simple, colourless ascospores. These spores typically lack internal divisions but occasionally develop a thin septum and measure 10–13 by 5–7 μm. The exciple, a rim of protective tissue surrounding the apothecium, is sometimes visible as a band of golden-brown cells, but the thalline exciple is absent. No asexual reproductive structures (conidiomata) have been observed in this species.[2]
Chemical analysis of C. austrochilenis reveals the presence of atranorin and additional unidentified substances, as detected by thin-layer chromatography.[2]
