Pycnidia: black, subglobose, mostly immersed, 50-160 µm in diam. wall: brown or pale blue (and then N+ red), 3-7 µm thick conidiophores: pale brownish or olivaceous, short conidiogenous cells: olivaceous conidia: pale to medium brown or olivaceous, simple, catenate, smooth to verruculose, 6-9 x 3-3.5(-4) µm. Hosts: Lecanora species, mainly of the L. chlarotera group; typically infecting the edges of the apothecial disc and the thalline margin, also on the thallus World distribution: Europe, northern Africa, North America, possibly cosmopolitan Sonoran distribution: southern California, and Baja California Sur, probably common. Notes: The conidia of this species were said to be smooth-walled by Hawksworth (1981b), compared to the distinctly verruculose conidia of the similar Vouauxiella verrucosa (Vouaux) Petrak & H. Sydow This is misleading, as the conidial wall of V. lichenicola is frequently uneven, appearing verruculose (see Etayo and Breuss ). The genuine V. verrucosa, also confined to Lecanora species, is a rare taxon, distinguished by more strongly verrucose conidia, that are distinctly broader (3.5-5 µm). Vouauxiella verrucosa has recently been reported from the U.S.A. (Virginia) on Lecanora cf. pallida (Diederich 2003) and might well exist in the Sonoran region. Vouauxiella lichenicola might also be confused with Lichenodiplis lecanoricola (with simple conidia) and L. lecanorae (with 1-septate conidia), that also grows on Lecanora; however, the conidia in those two species are not catenate, and the conidiogenesis is different.