Female bicoloured; body largely brownish yellow; tarsi, apices of tibiae and apices of femora paler, abdominal segments I & II also paler; antennal segments I & II yellowish brown, III & IV yellow with dark brown ring at extreme apex, V–IX dark brown; fore wing banded, brown with transverse clear area sub-basally and sub-apically; often slightly paler medially. Head longer than wide; eyes prolonged ventrally; without long setae; maxillary and labial palps with distal segment subdivided. Antennae 9-segmented; III & IV with linear sensorium that curves around distal apex and extends toward base of segment, with internal markings. Pronotum smooth, with no long setae. Mesonotum transversely striate, two pairs of setae medially. Metanotum with sculpture transverse on anterior half, weakly reticulate on posterior; median setae on posterior half of sclerite. Fore wing wider distally than near base; with two rows of setae; costa with setae but no cilia. Abdominal tergite I constricted at base, tergites without sculpture medially, discal setae small; tergite X with pair of small trichobothria. Sternites III–VII with 3 pairs of posteromarginal setae, discal setae forming a transverse row.
Male smaller and slender; antennal segment IV brown not yellow; abdominal tergite I longer than wide and with two longitudinal ridges on posterior half; X with trichobothria very small.
Intraspecific variation
Short-winged and apterous females have been studied from South Brazil.
Genus and similar species information
Stomatothrips is a New World genus that comprises eight species, half of them described from Central and South America. They are all ant-mimic thrips associated with grasses, and are remarkable in having maxillary and labial palps with the distal segment subdivided into small units. S.angustipennis resembles another Brazilian species, S. rotundus but females can be distinguished by the colour of antennal segment IV and the metanotal sculpture.
