Observed, photo'd and collected with Jackie Rogers.
See earlier discussion on this shrubby stand at https://www.inaturalist.org/observations/40233628, where the shrub was proposed originally as Comarostaphylis diversifolia, but then questioned to be Xylococcus bicolor by @ajwright - way to go Alex! When we went to check on the stand this year, 4.5 years after the Woolsey Fire, it was obviously Xylbic instead of Comdiv.
This location is ~65 km (40 mi) further west than any known record for the species on the mainland, and considerably north and ~40 km (25 mi) west of the Catalina Island records. This is the first known occurrence of the species in the Santa Monica Mountains. The voucher collected in 1967 by D. Wilken (https://www.cch2.org/portal/collections/individual/index.php?occid=2217112&clid=0) appears to have been mis-mapped in the Santa Monica Mountains, not by Wilken, but by a recent processor of the record using a Google Earth georef batch tool on 2021-03-02, placing the locality next to the Stone Canyon Reservoir in the eastern Santa Monica Mountains. However, Wilken's herbarium sheet label reads “Stone Canyon in the Verdugo Hills”. I just communicated with Wilken and he wrote on 29-March-2023, “I think that your assessment of the label locality text may be correct. I can't recall ever visiting a "Stone Canyon Reservoir" drainage or that particular part of the Santa Monica Mtns. However, I do recall visiting ‘Stough’ Canyon. The transcription error (Stough to Stone) on the label from field notes can't be verified but may derive from poor handwriting. I no longer have those field notes. And I wish that my dear college, botany buddy, the late Gary Wallace, was still alive to verify my recollection that it was he who told me about the locality in Stough Canyon and its confluence with Wildwood Canyon. I see from CCH2 that he collected it from there in 2000. I vaguely remember going back to the same locality with the field botany class I taught at Occidental College in 1971-1973. I also recall finding Diplacus (then Mimulus) puniceus in the vicinity.” Stough Canyon in the Verdugo Hills lies at approximately 34.214187°,-118.306890°. This places Wilken's record with several other known records of this species in the Verdugo Hills, and isolates our location on its own in the Santa Monica Mountains, and in the western quarter of the range no less.
Our collections will be distributed likely between the herbaria of the SMMNRA (herbarium code: SMMSH) and UCLA.