We're grateful to Jeffrey Ferguson, who alerted us to this previously overlooked early Flora cover.
Based on the catalog number (M-555) and some internet research, this cover dates from 1944, which would make it the earliest known illustrated Jim Flora cover. Though unsigned, the tiger-striped typography and horseback rider point to Flora as the artistic culprit. In 1944 he was art director of Columbia, which was issuing back catalog in 78 folio format owing to a recording ban (a musicians union stoppage) and a shellac shortage (due to the war effort). These Crosby recordings dated from the early 1930s.