Thallus: fruticose, creeping and attaching at several points along the lobes, sometimes also forming areoles when growing on more solid substrates lobes: discrete, elongate, and stringy, up to 30 mm long, 0.2-1.2 mm wide, terete, tips typically single and unbranched but sometimes forked prothallus: sometimes formed at the lobe tips or edge of areoles, black surface: white to gray or gray-green, sometimes in parts green or brown, dull and irregularly white mottled, remaining white in parts even when moist, without pseudocyphellae upper cortex: (15-)20-40 µm thick, uppermost part brown, 5-15 µm thick with cells (4-)5-8(-10) µm in diam.; cortex covered with an epinecral layer 5-14(-20) µm thick photobiont: chlorococcoid, cells ±round, 5-16 µm Apothecia: aspicilioid, rare, (0.1-)0.2-0.8(-1) mm in diam., round disc: black to brown-black, concave to flat, occasionally pruinose thalline margin: ±elevated, concolorous with thallus exciple: I-, 40-60(-80) µm wide; uppermost cells brown, ±globose, (3.5-)4-7(-8) µm in diam. epihymenium: brown to red-brown, without or with a few crystals, N+ green, K+ unchanged or intensifying brown to red-brown hymenium: hyaline, rarely slightly brown, I+ persistently blue or partly turning red-brown to yellow, (50-)60-110(-120) µm tall paraphyses: moniliform, with (2-)4-6(-8) upper cells ±globose to subglobose, uppermost cell 3-4.5(-5) µm wide, in lower part 2-2.5(-3) µm wide, slightly branched and anastomosing subhymenium and hypothecium: pale, I- or partly I+ blue, together 20-50(-60) µm thick asci: clavate, 60-80(-90) x 16-25 µm, (6-)8-spored ascospores: hyline, simple, ellipsoid, 12-18(-24) x 7-11 in the present material Pycnidia: rare to rather common, immersed, sometimes aggregated, 100-250 µm in diam., with a black, punctiform, often ±elevated ostiole, (70-)100-150(-200) µm in diam conidia: filiform, (10-)12-21(-23) x (0.6-)0.8-1 µm Spot tests: cortex and medulla I-, K+ red, P+ orange, C-, KC- Secondary metabolites: norstictic acid, sometimes also with trace of connorstictic acid. Substrate and ecology: on organic duller, rock, moss and litter, in chaparral habitats World distribution: California, predominantly at lower elevations Sonoran distribution: southern California. Notes: Aspicilia californica is characterized by its fruticose, white to gray or gray-green thallus, filiform lobes with usually simple tips, and the presence of norstictic acid (K+ red). Aspicilia filiformis is another fruticose species, occurring north and east of the Sonoran area (mainly in Oregon Idaho, Utah, Washington and Montana States and has one locality also in California). A. filiformis has an olive to brown thallus with forked lobe tips and it reacts K- (or weakly yellow). In the original description of A. californica (Rosentreter, 1998) the spores are described as subglobose and small (5.5 x 4 µm when 8 per ascus; 10 x 7 µm when 6 per ascus). In the specimens examined in the present study, the spores are usually ellipsoid and distinctly larger, 12-18(-24) x 7-11 µm, indicating a large variation in spore size.