TACHINIDAE OF AUSTRALIA 17 
subdivided by the transverse suture, but the terms prescutum and scutum 
remain useful in taxonomy. 
mesopleuron. The upper anterior part of the wall of the thorax between the 
anterior spiracle and the wing base (anepisternite) (Text-fig. 7). 
Of little use taxonomically. Presence or absence of a dense pollinose spot 
on the centre of the mesopleuron is occasionally useful at specific level (e.g. 
in Rutiliini). A small anterodorsal mesopleural seta may be developed but is 
little used taxonomically. 
notopleuron. A small subtriangular area differentiated laterodorsally on the 
thorax between the humeral callus and the wing base and external to the 
prescutum (Text-figs 4 & 7). 
Of very little use in taxonomy except as a minor aid in distinguishing between 
a few Proseninae. In Doleschallini the notopleura are not noticeably 
differentiated from the prescutum, and in a few Rutiliini (e.g. subgenus 
Neorutilia) the posterior part of the notopleuron is unusually swollen and 
knob-like. 
notopleural setae. The setae standing on the notopleuron (Text-fig. 4). 
In very nearly all Tachinidae these number two, one anterior and one posterior. 
Rarely additional setae are developed, e.g. in the Philippines species of Rutilia 
(Chrysorutilia) in which the posterior knob-like swelling of the notopleuron 
bears two strong setae (in place of the usual single posterior notopleural). 
occiput. The posterior surface of the head excluding the postorbits (Hinterkopf 
of Mesnil) (Text-fig. 1). 
occipital setulae. Recumbent black setulae or strong hairs on the upper occiput 
behind the postocular row (schwarzen Mikrochdten hinter den Postokularbértschen 
of Mesnil). 
Presence or absence of these setulae is often a useful taxonomic character at 
various levels. 
ocellar setae. The pair of setae standing very near the ocelli on the ocellar triangle 
or tubercle (Text-fig. 3). 
Presence or absence, orientation, and occasionally the precise position of 
the insertions relative to the ocelli are of taxonomic value and provide useful 
key characters. When present the setae are most often curved forwards and 
downwards (proclinate ocellars), but occasionally backwards (reclinate ocellars) 
(e.g. in Gonia, Elpe, Leucostoma); in a few forms they curve directly outwards 
towards the eyes (divaricate ocellars) (e.g. in Paragonia). 
ocellar triangle. The subtriangular area of the vertex on which the ocelli are 
placed (ocellar plate, vertical triangle, ocellarium) (Text-fig. 2). 
| Typically the ocellar triangle is slightly raised in relation to the rest of the 
_ vertex, and in forms with holoptic or subholoptic heads the ocelli are on a very 
| 
| 

prominent ocellar tubercle (e.g. most male Palpostoma). Ocelli are almost 
universally present in Tachinidae, but are vestigial or absent in some Ormiini 
(e.g. Therobia). 
_ outer vertical setae. A pair of outwardly curved setae standing laterally on the 
vertex close to the eyes (Text-fig. 3). 
B 

