Female macropterous. Body and legs brown; antennal segment III yellowish in basal half or two-thirds but brown distally, IV–IX brown; forewing brown at base including base of clavus, with long median brown area and two clear transverse bands; distal transverse band almost paralel-sided with pale costal vein.
Head with postocular region as long as eye length; mouth cone long, distal maxillary palp segment subdivided. Antennae 9-segmented, III–IV with sensorium almost encircling apex, strongly undulating and extending to basal third of segment, without internal markings. Mesonotum with 2 or 3 pairs of accessory setae medially. Metanotal reticles with internal dot-like or linear markings. Abdominal tergite I medially almost without sculpture; trichobothria on X no larger than base of major setae on X. Sternites with 3 or 4 pairs of marginal setae, discal setae varying from 0 to 2 laterally but none medially.
Male similar to female but smaller. Abdominal tergite I with two longitudinal ridges. Sternites with 0 to 2 pairs of discal setae laterally, IX without discal setae.
The genus Desmothrips is known only from Australia, with 18 described species (Pereyra & Mound, 2010). The sensoria on antennal segments III and IV in D. steeleae are long and strongly undulating, in contrast to the other species in the genus.
Known only from Australia
Widespread in eastern Australia, between Kangaroo Island and southeastern Queensland, but also recorded from Perth in Western Australia.
Apparently specific to the flowers of various species of Pultanaea (Fabaceae), including both low-growing and shrubby species.
Flower breeding, but probably predatory on other thrips in flowers.