Theretra gala
Male: Forewing upperside very similar to Theretra indistincta manuselensis but ground colour darker and deeper; the darker cloud that crosses the wing from costa to tornus just distal to the discal spot absent; discal spot larger; fourth postmedial line thicker and stronger; basal area darker and more clearly delineated. Occasional specimens of Theretra indistincta manuselensis approach Theretra gala in one or other of these characters, but not in all of them simultaneously. Forewing underside basal area same pale colour as rest of wing, except for a small blackish area along the inner margin, exceptionally reaching the discal cell (in Theretra indistincta manuselensis, the basal area dark and extends into and sometimes above the discal cell towards the costa and distally beyond the cell); black discal spot usually present (this spot is replaced by a white dot, or a white lining of the discal cell veins, in Theretra indistincta indistincta, Theretra indistincta manuselensis and Theretra indistincta papuensis, but is absent in Theretra indistincta bismarcki).
Female: Larger and broader winged than male, but otherwise identical in colour and pattern.
Male genitalia: Vesica similar to Theretra indistincta manuselensis in having a long and a very short diverticulum arising at the same distance from the apex of the phallus and positioned at an angle of about 120° to one another, but the long diverticulum arises from right side of the vesica, when vesica is viewed laterally from the left (in Theretra indistincta manuselensis, it arises from the left side). All other features of the male genitalia are more variable among individuals of Theretra gala and Theretra indistincta than between the two taxa.