McEvey: Drosophila setifemur species group 
37 
-- Abdomen largely pale, stramineous (straw yellow), fringe of 
heavy setation in about 0.5-0.7 of third costal section (tropical 
northeastern Australia, north of 20°S latitude), front with 
distinctive pruinescence in males only . 7 
7 Male fronto-orbits only, with distinct silvery pruinescence, visible 
especially at acute angles. 
-Male frons entirely covered with distinct silvery pruinescence, 
visible especially at acute angles . 
8 Female fore-femur with short closely spaced setae on more than 
the apical half of posteroventral surface, the longest one, at apex, 
not longer than the femoral diameter (Figs. 1, 4); C-index about 
2.4 (third costal section not less than a third the length of the 
second section); facial carina narrow; thorax brown, abdomen 
blackish-brown, subshining . Drosophila setifemur and D. prodispar 
-Female fore-femur with four or five widely spaced bristles 
on the entire length of posteroventral surface, the longest 
one, at or near middle, as long as or longer than the femoral 
diameter (Figs. 6, 9); C-index 3.7-4.7, facial carina very broad 
. Drosophila immigrans, D. rubida, D. sulfurigaster, D. niveifrons 
Drosophila sulfurigaster 
.... Drosophila niveifrons 
Biogeography and habitat preference 
A comprehensive morphological and genetic study of 
Drosophila setifemur and D. prodispar , especially where 
their ranges meet (or almost meet) near Melbourne, 
Victoria, could lead to a convenient new model for studying 
environmental adaptation, speciation and interspecific 
hybridization (note that setifemur x prodispar hybridization 
is currently unknown). Drosophila prodispar appears to 
occur only in the Otway Natural Region (Barlow, 1985) 
west of Melbourne while D. setifemur occurs in eastern 
Australia from just east of Melbourne to Queensland {Howe, 
Nepean, McPherson to Cape York Natural Regions ). 
Extensive fruit-baiting in Tasmania and the islands of Bass 
Strait might result in the discovery of additional isolated 
populations or even other species, although there is no 
evidence that any drosophilid speciation has resulted from 
sea-level rise in Bass Strait (Parsons & Bock, 1977). 
Atkinson (1985) has recorded D. setifemur (as D. 
dispar) on Black Apple Planchonella australis at Bruxner 
Park (30.2°S 153.1°E) near Coffs Harbour but numerous 
other fruits, flowers and fungi appear to be suitable for 
breeding. Moxon et al. (1982) report it as common at fruit 
and mushroom baits “from north Queensland-Victoria 
especially in floristically depauperate forests.” My 
collection records also indicate that it is common in fern and 
bracken ( Pteridium ) habitats, and is attracted to composted 
and rotting vegetables, flowers of Syzygium, rotting fruits 
of, for example, Citrus, Feijoa, and Opuntia, rotting 
mushrooms and other fungus, and it is taken in Malaise 
and pitfall traps. Parsons & Bock (1977) also note that D. 
setifemur (as “D. dispar”) is attracted to both mushroom 
and fermented fruit baits throughout its range, particularly 
in tree fern, Eucalyptus-Acacia and sedge habitats, but 
interestingly, to the west of Melbourne, they collected flies 
(which, by inference, must have been D. prodispar) only by 
sweeping and not at all by fruit- or mushroom-baiting. This 
suggests that it may be difficult to establish D. prodispar 
in culture. 
Collection records for drosophilid flies collected at fruit 
bait in the Nepean Natural Region (which includes Sydney, 
Barlow, 1985), indicate that Drosophila setifemur is the 
most common species when using this method in natural 
or semi-natural habitats (Table 1). 
Table 1 . The most frequently collected species of Drosophilidae using fruit baits in semi-natural habitats 
in the Sydney region with approximate abundance ratio indicated as a percentage (pooled data, variation 
between traps can be large). 
Drosophila setifemur Malloch, 1924 29% 
Drosophila immigrans Sturtevant, 1921 19% 
Drosophila simulans Sturtevant, 1919 17% 
Scaptodrosophila lativittata (Malloch, 1923) 11% 
Drosophila pseudotakahashii Mather, 1957 9% 
Drosophila serrata Malloch, 1927 6% 
Drosophila melanogaster Meigen, 1830 3% 
Scaptodrosophila Sydneyensis (Malloch, 1927) 3% 
Scaptodrosophila claytoni van Klinken, 1997 2% 
Scaptomyza australis Malloch, 1923 1% 
