Austrogorytes vs Argogorytes (BEMBICINI)
Workbook
cover image by Kerry Stuart, part of a wonderful series taken in a park near Perth in August 2024 and published on iNaturalist. https://inaturalist.ala.org.au/observations/235308189
Argogorytes is represented in Australia by four described species: Argogorytes rubrosignatus from Western Australia, plus three species from south-eastern Australia. The genus is superficially similar to Austrogorytes, and there are two WA species that can be particularly difficult to distinguish in field photos:
Argogorytes rubrosignatus and Austrogortyes pretiosus.
Thanks to Kerry Stuart and Terry Houston, we can now compare them side-by-side!
Often I must rely upon written descriptions of genera and species, and that can be problematic. It is always preferable to be able to complement text with verified images. Although not type specimens, the provenance of these is about as good as it gets … Bohart for Austrogorytes pretiosus, and Terry Houston for Argogorytes ?rubrosignatus.
In comparing the two species, attention is drawn to the following:
eye shape. This is a key difference between the genera. In Austrogorytes the inner eye margins are essentially convex, and they converge strongly below. In contrast, the inner eye margins of Argogorytes are sinuate and essentially parallel, the frons broad.
base of gaster. The first segment of the gaster is strongly constricted apically in Austrogorytes pretiosus, and the entire segment is much narrower than the second segment. This is not the case for Argogorytes ?rubrosignatus.
male clypeus colour. Both have a covering of silvery setae, but the underlying integument is yellow in Austrogorytes pretiosus, black in Argogorytes ?rubrosignatus.
Austrogorytes pretiosus
At the time of writing the genus review, Bohart (1984) knew of only a single male in collection: the holotype, collected near Yallingup, WA, and held by the British Natural History Museum.
The Western Australian Museum currently has one specimen, also a male. This wasp was found further north in WA, in the Avon Valley north-east of Perth and identified by Bohart in 1999 (Terry Houston pers. comm.). It is the specimen shown in the images above.
extract page 408:
Bohart, R.M. 1984. A revision of the genus Austrogorytes Bohart (Hymenoptera: Sphecidae). Australian Journal of Zoology, 32: 391-412
Argogorytes rubrosignatus
According to Bohart & Menke (1976) and the current information on AFD, Argogorytes rubrosignatus is known only from south-western Western Australia.
The images provided by Terry Houston are referred to Argogorytes, although the species assignment remains a little uncertain (as highlighted by the question mark). The colouration described by Turner is not quite a match for A. rubrosignatus, and I have not uncovered any later revision of this genus.
Austrogorytes vs Argogorytes
Back at the genus level, eye shape works best for distinguishing Austrogorytes from Argogorytes in a field photo.
Eye shape
Austrogorytes: inner margins converging below, often strongly; frons narrowest just below antennal sockets.
Argogorytes: inner margins sinuate, breadth at midocellus less than that just a short distance below; frons broad, just slightly narrowed toward clypeus.
I have also included Clitemnestra here, as this genus might be confused with Austrogorytes.
There are other differences noted in the genus descriptions (Bohart & Menke 1976), but these are either difficult to make out in most field images and/or they may vary between species within a genus.
References
Bohart, R.M. 1967. New genera of Gorytini (Hymenoptera: Sphecidae: Nyssoninae). Pan-Pacific Entomologist 43: 155-161
Bohart, R.M. 1984. A revision of the genus Austrogorytes Bohart (Hymenoptera: Sphecidae). Australian Journal of Zoology, 32: 391-412
Bohart, R.M. & Menke, A.S. 1976. Sphecid Wasps of the World: a Generic Revision. Berkeley: Univ. California Press
Turner, R.E. 1915. Notes on fossorial Hymenoptera. XV. New Australian Crabronidae. Annals and Magazine of Natural History 15:85: 62-96 doi.org/10.1080/00222931508693616
This is a workbook page … a part of our website where we record the observations and references used in making species identifications. The notes will not necessarily be complete. They are a record for our own use, but we are happy to share this information with others.