Body bicoloured, head and thorax brown but abdomen paler; final abdominal segments darker; tibiae and tarsi yellow, as well antennal segment III–IV; fore wings light brown but basal quarter paler. Head with two pairs of ocellar setae, pair III just in front of hind ocelli. Antennae 7-segmented, III unusually small; III & IV with forked sense cones. Pronotum with two pairs of long posteroangular setae; one pair of long setae close to anterior margin. Mesothoracic spinula present; metathoracic spinula absent. Metanotum with weak or no reticulation medially; paired campaniform sensilla absent; two pairs of setae, median pair short and arising behind anterior margin. Tarsi 2-segmented. Fore wing with first row of setae incomplete and second almost complete, with about 10 setae. Abdominal tergites without sculpture medially; ctenidia usually absent, but rudimentary ctenidia sometimes present on VI & VII; tergite VIII posterior margin with a few small microtrichia laterally. Sternites without discal setae and with three pairs of long posteromarginal setae; ovipositor unusually small. Both sexes fully winged.
Male with antennal segment III greatly reduced but IV–VI enlarged; abdominal sternites III–IV with two small circular pore plates placed laterally;posterior margin of abdominal tergite IX with two stout thorn-like setae arising from prominent tubercles.
Intraspecific variation
Not recorded.
Genus and similar species information
Plesiothrips is a Neotropical genus which comprises about 20 species, all of them showing weak ovipositor and antennal segment III reduced, mainly in males (Mound et al. 2016). Despite the differences observed in antennae, this genus might be related to Thrips, by exhibiting similar position of the rudimentary ctenidia on tergites VI & VII and also lacking ocellar setae pair I. A key to Plesiothrips species is given by Mound et al. (2016).
World distribution
Widespread in all continents, particularly common in Tropical countries.
Breeding on grass florets, particularly common on sugar cane.
Economic importance
Not recorded.
References suggested
Mound LA & Marullo R (1996) The Thrips of Central and South America: An Introduction. Memoirs on Entomology, International 6: 1–488.
Mound LA, Lima EFB, 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
