Scirtothrips aurantii Faure

Hoddle, Mark S. & Mound, Laurence A., 2003, The genus Scirtothrips in Australia (Insecta, Thysanoptera, Thripidae), Zootaxa 268, pp. 1-40 : 13-14

Scirtothrips aurantii Faure

[ Figs 3 , 22, 28 , 37 , 54 , 58 ]

Scirtothrips aurantii Faure, 1929: 3 ­8.

This species, the South African citrus thrips, was introduced to south eastern Queensland presumably around the year 2000, and by February 2003 had become established and widespread to the east of Brisbane. However, at the time of writing these populations remain associated only with members of the Crassulaceae , particularly the Bryophyllum species that are invasive weeds in pastures and along roadsides. This situation contrasts with that in South Africa, where S. aurantii is found not only on the leaves of native Acacia trees, but also on a very wide range of introduced plants including Citrus [ Rutaceae ] and Bryophyllum species, and the Australian tree Grevillea robusta [ Proteaceae ]. In Australia, only two species of Scirtothrips are known with microtrichial fields extending fully across the sternites. In S. aurantii , the microtrichia almost cover the entire surface of the sternites, whereas in S. dorsalis they are restricted to the posterior half of each sternite. The second instar larvae of these two species are similar in having reticulate sculpture on the pronotum ( Figs 58, 59 ), and very similar sculptured larvae have been found in association with adults both of S. albomaculatus and S. inermis . Adults of S. aurantii and S. dorsalis are readily distinguished from each other because the forewing posteromarginal cilia are wavy in S. aurantii but straight in S. dorsalis . Moreover, within this genus of 100 species, S. aurantii is unique in having a comb of stout dark setae on the posterior margin of the hind femora of the males.

Female macroptera. Colour: Body yellow with brown markings medially on tergites and sternites, and antecostal ridges on tergites and sternites dark brown; forewings weakly shaded, paler toward apex; antennal segment I pale, II dark, III – IV pale with apex shaded, V – VIII dark.

Structure: Head about twice as wide as long, postocular and ocellar region closely striate; ocellar setae pair III arise with ocellar triangle on or close to tangent between anterior margins of posterior ocelli, distance between their bases less than diameter of first ocellus; compound eyes with no ommatidia strongly pigmented; two pairs of post­ocellar setae longer than ocellar setae pair III. Pronotum closely striate, with 2 pairs of anterior marginal setae, 10­12 discal setae; 4 pairs of posteromarginal setae, S2 clearly longer than S1. Metanotal sculpture variable, transverse anteriorly, longitudinally reticulate posteriorly; median pair of setae at anterior margin. Forewing scale with 3­4 marginal setae; second vein with 2 – 5 setae; posteromarginal fringe cilia all weakly undulating. Tergites III­V with bases of median setae usually closer together than length of these setae; tergal microtrichial fields with 3 discal setae; VIII with discal microtrichia present anteromedially, posteromarginal comb complete; tergite IX with discal microtrichia absent. Sternites almost covered with microtrichia except anteromedially on VII; median setae on sternite VII arising slightly in front of posterior margin.

Male macroptera. Similar to female in colour and sculpture, but smaller; hind femur with row of 5 – 7 stout dark setae on distal posterior margin; aedeagus apparently with no armature.

Figures

FIGURES 1 ­ 10. Scirtothrips heads and pronota. 1, akakia; 2, albomaculatus; 3, aurantii; 4, australiae; 5, casuarinae; 6, dorsalis; 7, dorsalis; 8, drepanofortis; 9, eremicus; 10, dobroskyi.

FIGURES 21 ­ 31. Scirtothrips pro­ meso­ and metanota. 21, astibos; 22, aurantii; 23, aurantii; 24, eremicus; 25, australiae; 26, dorsalis; 27, dorsalis; 28, aurantii; 29, quadriseta; 30, moneres; 31, dobroskyi.

FIGURES 32 ­ 37. Scirtothrips pro­ meso­ and metanota. 32, pilbara; 33, akakia; 34, solus; 35, helenae; 36, drepanofortis; 37, aurantii male hind leg.

FIGURES 51 ­ 56. Scirtothrips abdominal sternites. 51, australiae V­VII; 52, dorsalis IV­VII; 53, frondis V­VII; 54, aurantii sternites V­VII; 55, albomaculatus sternites IV­VI; 56, quadriseta IV­ VII; 57, drepanofortis male tergites VIII­IX.

FIGURES 58 ­ 63. Scirtothrips second instar larvae, head and pronotum. 58, aurantii; 59, dorsalis; 60, frondis; 61, helenae; 62, tenor; 63, dobroskyi.