A tiny, nearly tailless quail-like bird with a heavy bill, an orange-rufous chest patch, a pale whitish undertail, and dark, heavily streaked, cryptically patterned upperparts. Small groups inhabit native grasslands and scrub in lowlands and on low ridges. Confined to Sumba. Differs from Red-backed Buttonquail in lacking red facial areas, lacking bold spotting along its flanks, showing a whitish undertail, and possessing a stouter gray bill without yellow coloration. In flight, it also shows heavier streaking above than Red-backed Buttonquail. Calls of Sumba Buttonquail are currently unknown.