Cerceris (PHILANTHINAE)
Workbook
Cerceris is a huge genus, with nearly 900 species worldwide (GBIF). There are currently 50 described species in Australia (AFD; Evans, 1982; Evans, 1988). Cerceris construct multi-celled nests in firmly packed soil. Most provision their nests with beetles (Bohart & Menke, 1976) – hence the common names of ‘digger wasps’ and ‘weevil wasps’. Larvae feed upon the deeply paralysed beetles stored in their cell. Adults take only nectar and honeydew.
Most Cerceris species are strictly solitary, but there is convincing evidence of nest sharing occurring in at least ten species (Polidori et al., 2006). Notably, this includes seven Australian species (C. antipodes; C. australis; C. goddardi; C. minuscula; C. unispinosa; C. windorum; C. xanthura).
Recognising the genus
Cerceris are quite readily distinguished from all other Australian crabronids. They are the only members of the subfamily Philanthinae … or what may soon be recognised as Philanthidae, alongside Crabronidae and Bembicidae (Sann et al. 2018).
The suite of characters that, together, are diagnostic for Cerceris include the shape of the gaster, the coarse sculpture of the body, and the shape and spacing of the eyes. These and other features characteristic of Cerceris are illustrated in the gallery below.
Distinguishing between species
Much of what we know of Australian Cerceris is down to the efforts of H.E. Evans, R.W. Matthews, and A.Hook. Evans based his detailed revision of the genus (1982) on material they collected during their various behavioural studies around the 1970s, alongside specimens from all institutions with significant holdings (including ANIC, Queensland Museum, Australian Museum, South Australian Museum, and the British Museum of Natural History).
In my experience, the distinguishing features most useful in field photos are: the head shape, most notably the clypeus in females; the petiole shape, for some species; and the colour pattern, particularly the gaster, legs, and in many cases the propodeum.
Colour varies, of course, and some species are particularly variable … most notably, C. antipodes. Such variation is noted in the summary table (matrix) below. Yet despite this, the overall colour pattern is (in Evans’ own words) “highly diagnostic” (1982, p. 301).
Drawing upon Evans’ 1982 revision plus a few subsequent works, I’ve developed a summary table which I continue to refine. Priority is given to those features that might be seen in field photos.
Click image to open/download latest version of this matrix (pdf, ~ 900kb)
Some of the more readily identifiable species
Despite the large number of species and the intraspecific variation of many, it is possible to confidently identify many of the more common species from field photos. Below are a few examples, just to illustrate the diversity in colour pattern. Cerceris are often strikingly colourful!
Please note. The above images are not intended as a definitive photo guide. The images are all linked to the source iNaturalist observations, and these should be checked for identification corrections and comments over time.
Bits & pieces
Various images and figures relevant to Cerceris identification, including key figures from Evans’ 1982 revision, lithographs from Turner’s various works, and museum specimens.
Images of museum specimens available online.
The following images were kindly provided by Dr Ben Parslow, Collections Manager, South Australian Museum (SAMA). These specimens are part of the SAMA collection, their identities determined by Howard E. Evans.
The images below are from BOLD. They are grouped by BIN (that is, similarity in DNA sequence), so images with the same BIN are probably the same species. Note that on BOLD no species have been identified beyond genus. The species ID suggestions are mine, based on these single, lateral images alone. They are therefore more or less tentative.
Select species, in detail
As opportunities arise, I take a closer look at individual Cerceris species.
**** Cerceris goddardi coming soon!
Life history and related ecological posts
Nesting Cerceris were among the first crabronids to attract my attention here in the forest. Over the years I’ve come to know them quite well, Where they nest and when. Who their neighbours are. Here are some of those tales.
References
[Many of Howard Ensign Evans works are publicly available via Wikispecies]
Bohart, R,M. & Menke, A.S. 1976. Sphecid Wasps of the World: A generic revision. University of Calfornia Press.
Evans, H.E. 1982 (Dec 1981 edition). The genus Cerceris in eastern Australia (Hymenoptera: Sphecidae). Transactions of the American Entomological Society, 107(4): 299-380 available here
Evans, H.E. 1988. Further studies on the systematics and nesting behavior of eastern Australian Cerceris wasps (Hymenoptera: Sphecidae). Transactions of the American Entomological Society, 114(1): 1-13
Evans, H.E. & Hook, A.W. 1982. Communal nesting in the digger wasp Cerceris australis (Hymenoptera: Sphecidae). Australian Journal of Zoology, 30: 557-568
Evans, H.E. & Hook, A.W. 1986. Prey selection by Australian wasps of the genus Cerceris (Hymenoptera, Sphecidae). Journal of Natural History, 20: 1297-1307.
Evans, H.E. & Matthews, R.W. 1970. Notes on the nests and prey of Australian wasps of the genus Cerceris. Journal of Australian Entomological Society, 9: 153-156
Sann, M., Niehuis, O., Peters, R.S., Mayer, C., Kozlov, A., Podsiadlowsk, L., Bank, S., Meusemann, K., Misof, B., Bleidorn, C. & Ohl, M. 2018. Phylogenomic analysis of Apoidea sheds new light on the sister group of bees. BMC Evolutionary Biology. 2018 May 18;18(1):71. doi: 10.1186/s12862-018-1155-8
Turner, R.E. 1908. Notes on the Australian fossorial wasps of the family Sphegidae, with descriptions of new species. Proceedings of the Zoological Society of London 1908: 457-535
Turner, R.E. 1910a. New fossorial Hymenoptera from Australia. Transactions of the Entomological Society of London 1910: 407-429
Turner, R.E. 1910b. Additions to our knowledge of the fossorial wasps of Australia. Proceedings of the Zoological Society of London 1910: 253-356
Turner, R.E. 1912. A revision of the Australian species of the genus Cerceris. (Hymenoptera.). Proceedings of the Linnean Society of New South Wales 36: 644-678
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.