Thallus endolithic IKI−, 1 cm wide, containing scattered algal cells in a gelatinized hyphal and substrate crystal matrix, visible as white round concave spots where apothecia have broken off. In the small pits, 1 or 2 new initials of apothecia form. Apothecia lecideine, lacking algae in the margin, stipitate, 0.3–0.7 mm wide, up to 0.4 mm thick, round to irregular, and eventually breaking loose from substrate probably after many years, not replicating by division. Margin melanized black, rugulose, sometimes tuberculate or incised and segmented, sometimes with long fissures parallel to edge of the margin, elevated above the immersed black rugulose disc, dark red when wetted. Parathecium formed from radiating hyphae, 1 μm wide, expanding to 100–120 μm around apothecia, outer layer melanized 20–100 μm wide, thickest at lower sides and bottom of apothecium, inner layer hyaline, 20–80 μm wide. Hymenium 60–100 μm high, epihymenium reddish brown, ca. 10 μm high, paraphyses 2–3 μm wide, apices expanded to 3–4 μm, with black pigment mark, hymenial gel IKI+ very dark reddish reaction, hemiamyloid. Center of apothecium divided by sterile column of hyphae extending through the hymenium, widening at top to form black double peaks above the epihymenium, IKI−. Algal layer below hymenium, 60–70 μm thick, divided by the sterile column of hyphae, algal cells 10–14 μm. Asci narrow to clavate, ca. 50–60 × 10–20 μm, ascospores globose, mostly 2 μm wide, some subglobose ascospores observed 3 × 2 μm. Subhymenium 30–50 μm high, IKI+ blue, euamyloid. Hypothecium continuous with parathecium and stipe, 200–300 μm thick, not dark or black. Pycnidia not observed.
Secondary metabolites: norstictic acid in parathecium, detected with TLC. Spot tests weak.
Ecology and substrate: on sandstone in full sun. World distribution: Tularosa Basin, Carrizozo Malpais, Chihuahuan Desert, New Mexico.
Notes: The apothecia eventually break off at the base of the stipe, leaving a white pit in the endolithic thallus. A feature unknown in other species of Acarosporaceae is the column of sterile hyphae continuous from the stipe through the hypothecium, dividing the algal layer and center of apothecium, finally widening at the top forming a double peak above the epihymenium (see picture in Knudsen et al. 2023).