Body light brown, tarsi and apices of tibiae yellow; fore wings light brown. Antennae 7-segmented, segment III much shorter than IV, both with forked sense cones; segment VI longer than IV. Head about as long as wide, slightly projecting in front of eyes; ocellar setae pair I absent, pair III just inside ocellar triangle; postocular setae in transverse row. Pronotum with two pairs of long posteroangular setae; metanotum with median setae posterior to anterior margin. Abdominal tergites without ctenidia, tergite VIII with no marginal comb, X with a median longitudinal split. Sternites without discal setae.
Male sternites III and IV each with two small pore plates placed laterally.
Intraspecific variation
Not recorded.
Genus and similar species information
There are 17 species listed in Plesiothrips, mostly light brown to yellowish brown with grey fore wings. All of them live on grasses, and the genus represents a radiation that is unique to the American continent. They all have the ovipositor weak with serrations almost absent, which suggests that they possibly deposit their eggs within grass flowers, rather than into plant tissues. Possibly related to the genus Thrips due to having a similar position of the rudimentary ctenidia on tergites VI & VII, and absence of ocellar setae pair I. Plesiothrips frequens is similar in colour and form to several other members of the genus, including the widespread species P. perplexus, but has the median pair of postocular setae arising in a slightly more anterior position, and antennal segment VI more elongate. A key to Plesiothrips species is given by Mound et al. (2016).
Moulton D (1938) Thysanoptera from Minas Geraes, Brazil.Revista de Entomologia9: 374–382.
Mound L, Lima E, O’Donnell C, Cavalleri A (2016) New World grass thrips of the genus Plesiothrips (Thysanoptera: Thripidae). Austral Entomology 55: 340–346.
Published in: 30/12/2016 Posted by: Mariana Lindner
