Similar to Macroglossum heliophila, but body and forewing uppersides paler, clayish. Abdomen upperside with dorsal basal dots vestigial; 7th segment pale, with a very conspicuous black mesial patch; side tufts all prominently white-tipped. Underside of palp, middle of thorax, and mesial patches on the proximal abdominal sternites dirty grey, much less white than in Macroglossum divergens. Forewing upperside antemedial band very prominent, sharply dilated basad posteriorly; 1st and 2nd discal lines curved as in Macroglossum divergens, but the 2nd not dilated distad posteriorly to vein M1. Both wings undersides more greyish distally than in Macroglossum divergens, the lines of the hindwing prominent. Hindwing upperside yellow band deeper yellow than in Macroglossum divergens, the edge of the black border less convex.
Male genitalia: Uncus prism-shaped, rounded dorsally, furrowed ventrally, apex truncate. Gnathos rounded apically. Valve with stridulatory scales. Harpe almost straight, sharply pointed. Phallus with 2 processes: one broad, hook-shaped, dentate on the concave edge; the other very long and slender, horizontal; long cornutus broad, terminating in a long point.
The specimen recorded as Macroglossum sitiene by Pan & Han (2018) (STI 21827) is purportedly from Beijing. It is the same specimen listed by Zhu & Wang (1983) (STI 20653) and Zhu & Wang (1997) (STI 20654) as Macroglossum saga. The genitalia match those of Macroglossum sitiene although the moth is small and there are some habitus differences from typical Macroglossum sitiene. It is treated her as a small Macroglossum sitiene but not mapped as Beijing is well outside the known range of Macroglossum sitiene and requires confirmation.