Vegetative hyphae: hyaline, BCr+ intense bluish violet Pseudothecia: black, globose, immersed to semi-immersed, 50-70 µm high and 45-70 µm wide wall: reddish brown, upper part darker than lower part, mostly 5-10 µm thick hamathecium: with periphyses and pseudoparaphyses of type a, 1.5-2.5 µm in diam., 8-17 µm long asci: clavate, sessile to shortly stipitate, 27-34 x 10-11.5 µm, 8-spored, endoascus BCr+ violet ascospores: hyaline to pale brown when mature, 1-septate, not constricted at the septa, cells of +equal size, oblong, ellipsoid to +subclavate, (9-)10-12.5(-13) x 3-4 µm, obtuse-ended; walls: smooth, thin, without a halo; epispore: BCr+ pale violet; inner perispore: BCr+ intense blue Pycnidia: immersed, 15-20 µm in diam. conidiogenous cells: 3.5-5.5 x 2-5 µm conidia: 2-3 x 0.5-1 µm. Hosts: apothecial discs of Caloplaca cerina var. chloroleuca, C. luteominia, World distribution: Europe, North America (U.S.A., Mexico) Sonoran distribution: southern California and Baja California. Notes: The description of Stigmidium cerinae above is based on material with Caloplaca cerina occurring outside of the Sonoran Desert region. Cole and Hawksworth (2001) report this species as new to North America giving Caloplaca luteominia and C. rosei as new host lichens. Unfortunately, they did not mention whether the specimens are growing on the host apothecia. As there exist at least two further possibilities of still undescribed species of Stigmidium occurring on thalli and apothecia of Caloplaca, that might be found also in the Sonoran Desert region, the identification of Stigmidium on Caloplaca at the species level is often regarded as uncertain, although all the hosts listed above do occur in the region.