52 
Records of the Australian Museum (2012) Vol. 64 
orange-brown coloration, and the conspicuously hirsute males. 
The locality data for C. vittatus suggest an association with 
fur seals ( Arctocephalus spp.), but this is not yet confirmed. 
Adult helosciomyzids may be collected by sweeping 
vegetation, but are generally sparse under held conditions 
and long series of specimens are rarely obtained. They are 
sometimes attracted to carrion (author’s experience and label 
data from S.B.P. and J.K.-P.). 
Steyskal and Knutson (1979) described the egg of “ Helo- 
sciomyza ferruginecT , but this involved a specific misidenti- 
hcation, the dissected female being referable to H. bickeli. 
The few rearing records for helosciomyzids suggest a wide 
range of larval habits, but do not include molluscivory, which 
is typical of true sciomyzids. A series of Eurotocus australis 
was reared from larvae in agaric fungi in South Australia 
(Steyskal and Knutson, 1979). Barnes (1980a) recorded 
larvae of Helo sciomyza subalpina Tonnoir & Malloch in 
New Zealand as predators of ant larvae and found that they 
fed on other freshly killed insects in the laboratory. Barnes 
(1980b) recorded larvae of Polytocus costatus Harrison from 
a seabird carcass in the Snares Islands. 
section of the costa (the thick vein on the anterior edge of 
the wing) near its base. It is particularly characteristic of 
the Cyclorrhapha, but is distinguishable in numerous other 
taxa. The term has been confused with basicosta, but I think 
that the latter term should be restricted to the part of the 
costal region between the tegula and the costagium. The 
basicosta is without setulae, though often with fine, pile-like 
microtrichia (Fig. 4; see also Crampton, 1942: fig. 71, bac). 
At its distal end the costagium may gradually narrow into 
the humeral section of the costa, which connects with the 
humeral crossvein; or it may be separated from the latter 
section by a costagial break (J. McAlpine, 1981: fig. 69). 
In the Helosciomyzidae, as in related families, there is no 
costagial break. The costagium bears a large anterodorsal 
bristle and a large anteroventral bristle, the latter bristle 
placed more distally (Fig. 4). This condition contrasts 
with that of the few taxa of Dryomyzidae now available to 
me, which lack the anterodorsal bristle, but is a common 
condition in numerous acalyptrate families. The basicosta 
consists of a short, flat anterodorsal plate and an anteroventral 
microtrichose tubercle. 
Morphology and relevant terminology 
I follow a traditional terminology with minimal use of terms 
implying doubtful, unproved, or, for present purposes, 
irrelevant homologies. Details are given by D. McAlpine 
(1973), with some additional terms given by D. McAlpine 
(1985, 2007). Most terms are also explained by Harrison 
(1959), Crosskey (1973), and Colless and D. McAlpine (1991). 
Terminology for the costal chaetotaxy follows Hackman and 
Vaisanen (1985), but they omitted mention of the costagium. 
I use the term lateral occipital suture for the suture 
separating the mesocranial plate or median sclerite from the 
lateral plate of the upper occipital region. With regard to the 
hind tibia, I distinguish the subapical anterior bristle from 
the preapical dorsal bristle (see Figs 1, 2), in accord with D. 
McAlpine (1991a: 32). 
The costagium is a partly dilated or thickened setulose 
Sexual dimorphism 
It is important to have some understanding of sexual 
dimorphism, in addition to that of postabdominal parts, 
in order to evaluate the taxonomic significance of certain 
characters, and to distinguish taxonomic differences from 
sexual differences (see D. McAlpine, 1992 in connection 
with Cobergius). Also, the nature of sexual dimorphism may 
indicate significant points in the biology of the insects, and 
may relate to mutual recognition by conspecific individuals 
(D. McAlpine, 1988). 
In flies of several schizophoran fa mili es the macrotrichia of 
some parts of the body are more numerous, longer, and finer 
in males than in females, and in the former they may have a 
tendency to be represented by mollisetae. Mollisetae are long 
macrotrichia (socket-based hair-like structures), which are 
strongly developed for part of the length, but are relatively 
thin and soft at their apices (D. McAlpine, 1991a). Mollisetae 
are present to a conspicuous extent in the males 
of certain species of Coelopidae, Helcomyzidae, 
Heteromyzidae, Piophilidae, and Scathophagidae. 
In some species of Helosciomyzidae larger 
numbers of mollisetae on the sternopleuron 
and fore femur of the males tend to replace 
the major bristles, which, however, 
remain well differentiated in con- 
specific females. Specimens of 
Helosciomyza spp. can be sexed 
solely by reference to the setulae 
on the ventral surface of the fore 
and hind femora, which are more 
numerous, finer, and more erect in males than 
in females. 
The legs of male helosciomyzids are frequently 
stouter than in conspecific females. This is particularly 
noticeable in the femora. Also some or all of the tarsal 
segments are often shorter and broader in males than in 
females (Figs 6, 7). 
Figures 1-3. Left hind tibia, anterior view of apical part. (1) Neosciomyza peckorum. (2) 
Helosciomyza bickeli. (3) Cobergius vittatus. as, apical ventral spurs; pd, preapical dorsal 
bristle; sa, subapical anterior bristle. 
