Body yellow with light brown markings; head and metanotum brown, ocellar triangle darker; pronotal blotch light brown; tergites II–VI with antecostal ridge dark, and brown markings anterolaterally; tergites VII–X yellow; fore wing brownish yellow; antennal segments I–III pale, IV brown; hind tibiae yellow, femora light brown at apex. Head with occipital apodeme confluent with posterior margin of eyes; mouth cone extending beyond fore coxae. Antennae 8-segmented, III & IV with forked sense cones. Pronotum transversely striate-reticulate on anterior area, blotch striate, posteroangular setae about twice as long as median length of blotch; mesonotal setae almost in transverse row; metanotum with poorly defined striations; metasternal plate with deeply U-shaped emargination. Tarsi 2-segmented. Fore wing first setal row complete, second row with no setae. Abdominal tergites I–VIII covered with microtrichia in closely spaced rows; II–VIII with a pair of long and close together median setae; VII-VIII posterior margin with complete comb of microtrichia; tergite IX with 3 pairs of mid-dorsal setae. Sternites covered with microtrichia, including medially; three pairs of long posteromarginal setae. Both sexes fully winged.
Male with sternites V–VII each with one circular pore plate.
Intraspecific variation
Not recorded.
Genus and similar species information
About 40 species are included in Hydatothrips, most of them bicoloured and with banded fore wings. This group is closely related to Neohydatothrips and can be distinguished by the presence of a deeply V-shaped apodeme on metasternum. Hydatothrips williamsi is characterised by having the four mesonotal setae almost in a transverse row, antennal segments slender and tergite IX bearing three pairs of mid-dorsal setae.
World distribution
Described from Caribbean Islands, and recorded from Brazil and Ecuador (Galápagos Is.).
