Cephonodes xanthus Rothschild & Jordan, 1903, Novit. zool. 9 (suppl.): 463 (key), 465. Type locality: [Japan:] Loo Choo Islands [Nansei Shoto, Ryukyu Archipelago], Okinawa.
Resembles Cephonodes janus janus and Cephonodes trochilus in the unicolorous buff-green upperside of the abdomen, and the latter especially in the somewhat deeper tint posteriorly. Distinguishable from both by the broader forewing apical patch and the black abdominal tuft. Forewing upperside with marginal band more than 3mm broad at Rs4. Underside of head, thorax and abdomen orange. Easily separable from Cephonodes armatus armatus by the absence of a foretibial claw. With a prominent black side line in front of and a white line around the eye.
Japan: 13.v-5.vi (Kyushu); 26.vii (Yakushima).
Larval hostplants. Unknown.
Japan: Shikoku; Kyushu (Cape Sata; Nichinan); Tanegashima; Tokara Island; Ryukyu Archipelago (Amamioshima; Okinawa; Yakushima).
Endemic to Japan.