Hypothallus endosubstratal, IKI−. Thallus squamulose, covering several centimeters, squamules distinctly variable in shape and color, up to 2 mm wide, up to 0.4 mm thick, with stipe up to 0.2 mm tall, or lichenicolous, scattered among the thalli of A. novomexicana, morphing out of the host (field observation). Upper surface light to dark brown with some black patches, epruinose to densely prui nose, young squamules smooth without fissures, older squamules densely cross-hatched with fissures, replicating by division. Lower surface corticate, 10–20 μm thick, white. Epicortex thin, 10 μm or less. Cortex variable from 20 μm at edges of large squamules up to 40–50 μm thick in center, cells 2–5 μm wide of disarticulated hyphae, round to irregular, or vertical hyphae 2 μm wide, top layer of cells 10 μm thick and dark brown to black, lower layer hyaline. Algal layer thick and even to uneven, 100–120 μm thick, interrupted by scattered hyphal bundles mostly 15 μm wide but may look uninterrupted depending on section mounted, extending down sides of the deep subhymenium. Medulla of vertical hyphae 2–3 μm wide, continuous with stipe, 150–250 μm thick. Apothecia infrequent, sometimes hard to observe unless wetted, 1 or 2 per squamule, immersed, slightly darker reddish brown than thallus, round to elongate and slit-like, 0.2–1.0 mm in width or length depending on shape, sometimes dividing. Parathecium expanding up to 50 μm around apothecium, intergrading into cortex, hyphae ca. 1 μm wide. Hymenium 80–100 μm high, epihymenium dark brown, 10 μm high, covered with IKI− polysaccharide layer, paraphyses 1.0–2.0(–2.5) μm wide, apices slightly expanded in gel caps up to 4 μm wide, hymenial gel IKI+ blue turning red in squash preparation, hemiamyloid. Asci mostly cylindrical 60–80 × 10–12 μm, or clavate, 60–80 × 15–20 μm, ascospores ellipsoid mostly 5 × 1.5–2.0 μm, variable. Subhymenium V-shaped up to 120 μm high, IKI+ dark blue. Hypothecium 20 μm thick, encasing subhymenium. Pycnidia not observed.
Secondary metabolites: none with TLC. Ecology and substrate: Chihuahuan Desert in New Mexico, known from Organ Mountains and Tularosa basin, on rhyolite and sandstone, facultative parasite on Acarospora novomexicana.
Notes: It is a distinctive species. Some collections be sterile. It is like A. applanata developing thalli cross-hatched with abscission fissures.