Gila Monsters (Heloderma suspectum) are rarely seen in California with only 27 credible sightings reported in over 150 years. A previously unreported specimen was observed 30 April, 1974 near Black Mountain in the southern Chocolate Mountains of Imperial County. The area fits many of the criteria of Gila Monster habitat elsewhere in California and is relatively close to several other credible and possible records in the state.
Lovich, Jeff and Haxel, Gordon
"A previously unreported locality record for the Gila monster,"
Bulletin of the Southern California Academy of Sciences:
Available at: https://scholar.oxy.edu/scas/vol110/iss2/1