Apothecia: black, adpressed to sessile, +round, 0.3-0.8 mm in diam., with thin prominent margin exciple: reddish brown in section, 25-50 µm thick, marginally cells arranged in indistinct radial rows, composed of subglobose to ellipsoid cells up to 10 µm in diam. hymenium: hyaline, 50-65 µm tall paraphyses: septate, c. 2 µm wide, only in the upper part sometimes with some branches, with tips enlarged up to 5 µm, provided with dark red-brown pigment caps hypothecium: reddish brown or pale with pigmented patches, composed of short-celled interwoven hyphae, 30-60 µm thick asci: broadly cylindrical to sub-clavate, 40-55 x 8-12 µm, 8-spored ascospores: brown, when mature mostly 3-septate, but some 1- or 2-septate always present, often slightly constricted at the septa, 9-15 x 3.5-5 µm Conidiomata: not observed. Hosts: Pertusaria species; hosts known outside the Sonoran region: Pertusaria hymenea, P. communis, P. albescens, Ochrolechia spp.; on the thallus and if present apothecia; commensalic, the infested host thalli not significantly damaged World distribution: widely distributed in Europe, also known from Asia, northern Africa, North America (Canada, U.S.A.), and New Zealand Sonoran distribution: so far reported only from a single locality in southern California. Notes: The only record in the Sonoran region is that by Weber et al. (1987: 23, as "Leciographa cf. parasitica Massal."). As the authors mention an unidentified corticolous Pertusaria as host, the fungus they had found was certainly not that species, which is now known as Opegrapha parasitica (A. Massal.) Vězda and which is restricted to calcareous crustose lichens, such as Aspicilia calcarea. It is more likely that they collected a specimen of D. parasitica. Dactylospora parasitica has already been reported by Tuckerman (1866: 26) from the Pacific coast (leg. Bo-lander) without further data but probably in the San Diego area. Also Fink (1935) lists California among other states, from which D. parasitica is known. Only a reinvestigation of Weber's or Bolander's specimen would show if D. parasitica is definitely present in the Sonoran region.