Ascomata: solitary, 0.14-0.26 mm high, stalk: medium to pale brown, short, 0.04-0.06 mm wide, 0.08-0.28 mm high, composed of thin-walled, cylindrical intertwined cells 2.5-3 µm long capitulum: black, shining, pyriform, 0.07-0.26 mm in diam. exciple: in outer part pale gray to white, in inner part brown, 10-12 µm thick, forming 4-6 layers of periclinally arranged, 1-2 µm wide hyphae; epithecium: thin, pale; hypothecium hyaline, formed of irregularly branched and intertwined hyphae, 1.5-2.5 µm in diam. asci: when mature with strongly and uniformly thickened apices without canal, 52-69 x 3.5-5 µm ascospores: 1-septate, septum distinct and of similar contrast as the outer wall, brown, ellipsoid with pointed ends, with a minute ornamentaion of smoothly rounded, irregular verrucae, 9-11 x 4-5.5 µm, with a thin hyaline or pale brown coat in both semi-mature and mature spores Spot tests: all parts of ascomata K-, N+ brownish red, I- Secondary metabolites: none identified. Substrate and ecology: parasitic or parasymbiotic on the thallus and ascomata of Lecanora in tropical and subtropical areas World distribution: Réunion, Australia, Brazil, and Mexico Sonoran distribution: Baja California Sur. Notes: Chaenothecopsis kalbii is characterized by its 1-septate, large spores, and the short-stalked, pyriform apothecia with a black capitulum and pale stalk.