Distinguishing features

Female macroptera. Body yellow, antecostal ridges on tergites and sternites dark; fore wings shaded near base but pale distally; antennal segment I pale, II – VIII darker. Head with vertex closely striate, ocellar region with several transverse lines; ocellar setae pair III about twice as long as diameter of one posterior ocellus, close together between midpoints of posterior ocelli; two pairs of post-ocular setae. Pronotum with transverse striae not closely spaced, distance between lines about equal to diameter of a discal setal pore; posteromarginal setae S2 50-65 microns long, more than twice diameter of antennal segment II. Metanotal reticulation arcuate anteriorly but almost equiangular on posterior half; median setae close to anterior margin. Fore wing clavus with 4 marginal setae; first vein setae with about 10 setae; second vein 2-3 setae; all posteromarginal fringe cilia straight. Tergite I without long discal setae, III-V median setae longer than distance between bases; tergal microtrichial fields with 4–6 discal setae; VIII with discal microtrichia anteromedially, posteromarginal comb complete; IX without discal microtrichia. Sternites III-VI with microtrichial fields extending just mesad of setae S2.
Male not recorded in Australia.

Related species

The genus Scirtothrips comprises over 100 described species worldwide, with 21 species known from Australia most of which are endemics to this continent. These species all have the lateral thirds of the abdominal tergites covered in closely spaced rows of fine microtrichia, and in many species the sternites also bear similar microtrichia. The antennae are 8-segmented, except in S. casuarinae and S. solus, both fore wing veins have an irregular and incomplete setal row, and a median spinula is present on both the meso and metafurca. S. inermis is similar to S. dobroskyi in having unusually long posteromarginal setae S2 on the pronotum, but the ocellar setae pair III are longer than in any endemic Australian species. S. inermis usually has at least one more discal seta on the tergal microtrichial fields than in other members of the genus. The male is described as lacking drepanae on the ninth tergite, but no male has been seen from Australia.

Biological data

Feeding and breeding on young leaves, and taken in considerable numbers from peach and citrus trees on Norfolk Island (Mound & Wells, 2015), but adults also taken from Viburnum sp [Caprifoliaceae] and Gerbera sp. [Asteraceae].

Distribution data

Described from Canary Islands, and recorded from California, New Zealand and Australia (Victoria, South Austrlia, Norfolk Island).

Family name

THRIPIDAE - THRIPINAE

Species name

Scirtothrips inermis Priesner

Original name and synonyms

Scirtothrips inermis Priesner, 1933: 186.

References

Hoddle MS & Mound LA (2003) The genus Scirtothrips in Australia (Insecta, Thysanoptera, Thripidae). Zootaxa 268: 1–40. http://www.mapress.com/zootaxa/2003f/zt00268.pdf

Mound LA & Wells A (2015) Endemics and adventives: Thysanoptera (Insecta) Biodiversity of Norfolk, a tiny Pacific Island. Zootaxa 3964 (2): 183–210. http://www.mapress.com/zootaxa/2015/f/zt03964p210.pdf