Body brown, legs light brown with apices of tibiae paler and tarsi yellow. Antennae 8-segmented, segment I with pair of setae dorsally at apex; segment III shorter than IV, both with forked sense cones; IV with prolonged apical neck. Head about as long as wide, slightly projecting in front of eyes; ocellar setae pair I absent, pair III just inside ocellar triangle; postocular setal row with median pair displaced to posterior. Pronotum with weak sculpture, two pairs of long posteroangular setae; metanotum with median setae posterior to anterior margin. Abdominal tergites without ctenidia, tergite X without a median split. Sternites without discal setae.
Male not known.
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 amblycauda is one of three species in the genus with 8-segmented antennae, but unlike P.longicollis there is not a pair of setae in front of the first ocellus, and unlike P. octarthrus sternite III does not have a pair of pore plates. A key to Plesiothrips species is given by Mound et al. (2016).
Hood JD (1925) New neotropical Thysanoptera collected by C.B. Williams. Psyche 32: 48–69.
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
