Female macropterous. Body and legs brown; antennal segments brown but III paler in basal half; forewing including clavus extensively pale with shaded veins and 2 weakly shaded transverse bands, apex mainly pale with ring vein dark.
Head with postocular region longer than eye length; distal maxillary palp segment subdivided. Antennae 9-segmented, III with sensorium straight and extending to basal third of segment, without internal markings, sensorium on IV curving around segment apex. Mesonotum with 3 pairs of accessory setae medially. Metanotal reticles equiangular medially, with dot-like internal markings. Abdominal tergite I without sculpture; trichobothria on X scarcely twice as wide as base of major setae on X. Median sternites with 4 pairs of marginal setae but no discal setae although lateral marginals are displaced forwards; VII with 4 pairs of marginal setae, 3 pairs of discal setae laterally.
Male similar to female but smaller. Abdominal tergite I with two longitudinal ridges. Median sternites apparently without discal setae, VII–VIII with at least 20 long fine setae arranged irregularly, IX with more than 30 long fine discal setae.
The genus Desmothrips is known only from Australia, with 18 described species (Pereyra & Mound, 2010). The forewing of D. marilynae is unusual within this genus, in that the apical part of the wing membrane is almost colourless although with the ring vein dark. Also, the male has a large number of long fine setae on the posterior sternites.
Known only from Australia
Known only from Western Australia, in the general area near Geraldton.
Collected from the flowers of various species of Myrtaceae in the genera Beaufortia, Melaleuca and Verticordia.
Adults of both sexes have been found in low numbers in various flowers, where they presumably act as facultative predators on the larvae of other thrips species.