Herbaceous geophyte, 30-250 mm tall, with erect, rigid stem; tubers broadly ovoid to spherical, 13 x 10 mm. Leaves 7-14, cauline, ± rigid, 50-120 mm long, basal leaves longest, with hyaline sheath, linear, becoming lanceolate-attenuate higher up and grading into shorter broader bracts, canaliculate, acute, mostly green but shading into maroon along upper margins and at tips. Inflorescence conical becoming ellipsoid to cylindrical, 40-130 x 30-35 mm, densely 6-150-flowered; bracts narrowly ovate to ovate, 13 x 4 mm, acuminate, naviculate, as long as or shorter than flowers. Flowers resupinated, facing outwards (patent) with mouth clearly visible, mildly scented; dorsal sepal suberect, galeate, 7-9 x 4-5 mm, externally shallowly slightly pouched longitudinally, mouth of galea ovate to elliptic, 6-8 x 3.5-5.0 mm, acute, often in same line as ovary, magenta with anterior lateral portions paler and brighter than midzone, pouches verrucose otherwise glabrous and shiny, deeply and narrowly grooved for 2/3-3/4 its length with groove continuing into spur, markedly ridged internally, ridge 1.5-2.0 mm deep, sometimes purple maculate, mostly smooth inside towards base with entrance to spur minutely papillate with white globose bodies extending just into spur, entrance to spur with two lateral greenish ridges running down into spur; spur 1.0-1.5 x 1.5-2.0 mm, semitriangular in lateral outline with upper edge longer, ± parallel sided, emarginate, deeply grooved above and forming 2 cylinders, groove apically with short narrow median ridge sometimes protruding slightly from apex and forming a small knob in emarginate apex, point of attachment to galea below slightly indented and concave, magenta or with basal greenish ring, sometimes totally dull green; lateral sepals narrowly ovate to elliptic, sometimes oblique, 5.5-8.0 x 2.5-4.0 mm, straight but sometimes slightly curved upwards, spreading outward at an angle of 60-80° between lip and sepal, pure white adaxially but sometimes variably magenta on upper margin, abaxially white to greenish with 2 mm long dark magenta bar towards upper edge; petals 4 x 2 mm, attached to rostellum by narrow erect lateral flange, white, bifid, anterior lobe exserted up to 1 mm beyond galea mouth or reaching mouth of galea but posterior to stigma, mostly square with acute, sometimes greenish apex, posterior lobe narrowing posteriorly, white with yellowish upper margin, rarely purplish spotted, apex curved inwards and forwards, sometimes downwards, green, often clasping galea ridge; lip mostly ligulate, 4.5-7.0 mm long, acute, sometimes narrowed medially, white, sometimes tinged green at apex, rarely with slight purple margins. Rostellum 2-lobed, lobes 1 mm long, narrow, canaliculate, erect to slightly forward pointing, parallel in a U-shaped arrangement, variously purple-spotted, with white lateral auriculate appendage projecting 1.0-1.2 mm on either side to under anther sacs, subpendant, tuberculate-verrucose. Anther sacs ovoid, 1.5 mm long, subpendant to pendant at 45°. Stigma shortly columnar, 1 x 1 mm, erect to 45° forward, placed outside galea, with purple anterior ridge. Ovary cylindric-ellipsoid, 8-9 mm long.
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Like D. obtusa but flowers white and magenta, spur not longer than broad, and stigma well in front of galea.