Family OXYGASTRIDAE
Compiler and date details
W.W.K. Houston, Australian Biological Resources Study, Canberra, ACT, Australia J.A.L. Watson, CSIRO Entomology, Canberra, ACT, Australia Updated (1999) by A.A. Calder, CSIRO Entomology, Canberra, ACT, Australia
Introduction
The Oxygastridae contains three genera and 10 species worldwide (Bridges 1994). It is represented in Australia by the endemic monotypic genus Hesperocordulia that is confined to the south-west of Western Australia. The genus Hesperocordulia was previously regarded as belonging to the corduliid subfamily Gomphomacromiinae by Theischinger & Watson (1978, 1984) and Watson et al. (1991). However, Bechly (1996) regards it as belonging to a separate family. The adult is described and illustrated in Theischinger & Watson (1978) and the larva is described in Theischinger & Watson (1984).
Diagnosis
Adult: medium-sized, orange-red and black dragonflies with very long legs; head large; primary antenodals Ax1 and Ax2 of forewing strongly differentiated, more widely separated than secondaries; pterostigma elongate, 3-4 times as long as wide; arculus between Ax1 and Ax2 distinctly closer to Ax1 in both wings, slightly proximal to triangle in hindwing; sectors of arculus arising from a common point or slightly separated at base in both wings; hypertriangle and triangle of both wings and subtriangle of forewing free; both wings with a single cu-a; costal side of hindwing triangle up to 1.7 times the length of the proximal side; discoidal field of hindwing divergent, beginning with two rows of cells; anal loop elongate, generally in 2 rows; all tibiae with keels; anterior lamina of male secondary genitalia large, deeply emarginate in midline; hamule armed at apex; female valves reduced, posterior margin of sternite 8 excavated; anal appendages of male long, superiors about twice as long as inferior, more than 3 times length of segment 10; anal appendages of female about twice length of segment 10.
Larva: head hairy, short, very wide; eyes strongyl protruding laterally; prementum long narrow at base, very wide distally; ligula slightly convex to bilobed with two groups of premental setae; labial palp with 8 rounded teeth, set with bristles; end hook strong and straight; 6 large palpal setae; antennae 7-segmented; prothorax hairy, with rounded notal lobe and rounded processes; legs very long; wing sheaths reaching to about the middle of abdominal segment 5; abdomen very flat, wider than head; tergites 7-9 with small, sharp and slightly inwardly curved lateral spines; posterior margin of tergite 9 strongly concave; segment 10 directed dorsad.
General References
Bechly, G. 1996. Morphologische Untersuchungen am Flügelgeäder der rezenten Libellen und deren Stammgruppenvertreter (Insecta; Pterygota; Odonata) unter besonderer Berücksichtigung der Phylogenetischen Systematik und des Grundplanes der Odonata. Petalura, Special volume 2: 1-402
Bridges, C.A. 1994. Catalogue of the family-group, genus-group and species-group names of the Odonata of the world. Urbana, Illinois : C.A. Bridges xiv 951 pp.
Theischinger, G. & Watson, J.A.L. 1978. The Australian Gomphomacromiinae (Odonata: Corduliidae). Australian Journal of Zoology 26: 399-431
Theischinger, G. & Watson, J.A.L. 1984. Larvae of Australian Gomphomacromiinae, and their bearing on the status of the Synthemis group of genera (Odonata: Corduliidae). Australian Journal of Zoology 32: 67-95
Watson, J.A.L., Theischinger, G. & Abbey, H.M. 1991. The Australian Dragonflies. A guide to the identification, distributions and habitats of Australian Odonata. Canberra and Melbourne : CSIRO vii 278 pp.