Thallus: fruticose, shrubby erect to decumbent, up to c. 2 cm high lobes: narrow, ±isodiametric, up to c. 1 mm across, with fusiform apices outer surface: pale grayish brown to dark olive-brown, paler in central parts, frequently ridged and knobby, in parts covered with a whitish pruina cortex: strongly white, prosoplectenchymatous isidia: absent; soralia: absent; pseudocyphellae: occasional, immeresed; lobulae: side lobes present, cilia-like medulla: white, loosely packed; photobiont: a Trebouxia Apothecia: very frequent, terminal subterminal or lateral, convex, pedicellate; margin: prominent, with thalloid rim; disc: imperforate, olivaceous brown; exciple: hyaline; epithecium: brown or brownish yellow; hypothecium hyaline asci: clavate, lecanoral, 8-spored ascospores: hyaline, simple, ellpsoid to broadly ellipsoid, 7-8.5 x 3-4 µm; walls: thin, hyaline, not amyloid Pycnidia: laminal, immersed or emergent and sessile conidia: bifusiform, 5-7 x 1(-1.5) µm Spot tests: all negative Secondary metabolites: cortex with an unknown pigment, medulla with lichesterinic and protolichesterinic acids and 2-3 other low-Rf fatty acids. Substrate and ecology: on wood rather than bark World distribution: hypermaritime along the North American Pacific coast from California to southern Alaska Sonoran distribution: southern California (San Luis Obispo Co. and possibly San Diego Co.). Notes: Kaernefeltia californica has occasionally been confused with narrow-lobed specimens of K. merrillii. However, the former species usually differs by having a paler, often pruinose thallus, a pronounced knobby surface. Furthermore, K. californica is always richly fertile and the apothecia are usually terminally positioned. The distribution of the two species overlaps along the Pacific Coast, but K. merrillii also occurs in more inland localities, especially to the north where it is found in intermountain areas. The fruticose habit explains the former position in Cornicularia for K. californica. A recent DNA-investigation reveals a close relationship between the two Kaernefeltia species (Thell et al. 2007). Although Hasse (1895, 1898a, 1905, 1908b and 1913b) repeatedly cites K. californica as occurring in southern California, at least three of his specimens [nos. 192 & 210 from the Santa Monica Range and Krypt. Exs. Vind 1047 from the San Jacinto Mountains] have been annotated to K. merrillii (Kärnefelt 1980; Thell and Goward 1996). The most probable record from the Sonoran region is the Bolander specimen (Reliquae Tuck. 26), which may have been collected at Point Loma (San Diego Co.) during his west coast voyage. However, the label information is imprecise, as it only specifies California, and it may have been collected when he was in San Francisco as well.