Thrips australis (Bagnall)

Mound, Laurence A. & Masumoto, Masami, 2005, The genus Thrips (Thysanoptera, Thripidae) in Australia, New Caledonia and New Zealand, Zootaxa 1020 (1), pp. 1-64 : 18

Thrips australis (Bagnall)

Isoneurothrips australis Bagnall, 1915: 592

Thrips lacteicorpus Girault, 1926a: 17

Thrips mediolineus Girault, 1926a: 18

Anomalothrips amygdali Morgan, 1929: 5

Diagnosis: Body yellow to brown, female typically yellow with brown postoccipital ridge on head, brown markings medially on each tergite, and tergites VIII–X brown; forewing pale but shaded along veins, major setae often dark. Antennae 7­segmented, VI large and bullet­shaped; head with ocellar setae III arising inside ocellar triangle. Pronotal posteromarginal apodeme usually stout, postero­angular setae short ( Fig. 5). Metanotum reticulate, but reticles without internal markings ( Fig. 8), median setae arise behind anterior margin, campaniform sensilla present. Forewing with first vein setal row almost uninterrupted, clavus with 6 marginal setae ( Fig. 9). Abdominal tergite II with 4 lateral setae, VIII with marginal comb not developed medially ( Fig. 6); sternites with 15–40 discal setae, pleurotergites with 6–10 discal setae ( Fig. 7).

Breeding: Adults of this common species, the gum tree thrips, fly freely and may be found on many different plants, but females breed primarily in the white flowers of various Eucalyptus species , and less commonly in several other white­flowered Myrtaceae , particularly some white­flowered Melaleuca species. When populations are high in the flowers of Eucalyptus trees and these flowers begin to die, adults of T. australis may be found in large numbers on many surrounding plants.

Distribution: Found widely across Australia, also in many other parts of the world to which Eucalyptus species have been introduced. Kirk (1987) and Sakimura (1967) have both questioned whether T. australis is native to Australia, on the basis that this species has been found in so many countries around the world. However, neither of these authors considered the many field observations that so closely associate this thrips with white Eucalyptus flowers, both in Australia and in other countries. In countries as different as southern Brazil, Costa Rica, Chile and Kenya, T. australis is not commonly collected, but in each of these countries it has been taken in large numbers whenever suitably flowering Eucalyptus trees have been examined.

Relationships: Two character states are distinctive for this species: the “bullet­shape” of antennal segment VI and the presence of 6 (rather than 5) setae on the margin of the forewing clavus. Apart from these, T. australis is a typical member of Thrips genus ( Mound, 2002), and it shares many character states with T. imaginis . Segregating it to a monotypic genus Isoneurothrips (see zur Strassen, 2003) fails to represent such relationships satisfactorily.