Chimiloides (CRABRONINAE: Crabronini)
Workbook
A recent iNaturalist observation drew my attention to this small endemic genus. I had previously read a little about Chimiloides when compiling summary tables of the subfamily and tribe, but had not located any images. The photos in iNaturalist obs 291696449 – an orange-bodied crabronid from Victoria – are the first images I’ve seen of a wasp that may prove a match for Chimiloides.
After a few days of enthusiastic digging in the literature, I’m now more confident in recognising this genus … and I think it likely that iNaturalist observation 291696449 is indeed Chimiloides. There are just three described species in the genus, and this seems a very good fit for one of them.
Below is a summary of what I’ve learned about Chimiloides, plus links to the relevant references.
Genus-level identification
The genus Chimiloides was erected by Jean Leclercq (1951) to accommodate two species of Australian crabronids. Among the generic characters highlighted by the author at the time were:
overall stocky appearance
gaster sessile
coarse sculpturing, particularly of the head and thorax
strongly concave front of the head, not margined above
pronotal collar with strong lamellar carina
prepectus edged anteriorly
verticaulus strong
The same author added a third species a few years later (Leclercq 1954), and has further revised the genus since then. Leclercq’s most recent revision is particularly relevant, correcting several earlier errors in species descriptions and providing a key to males and females of each species (Leclercq 2007).
Among Australian crabronids, Chimiloides is most similar to Ectemnius, Williamsita and Lestica. To compare the genera, see my updated summary table for the tribe (link below).
Species-level identification
Extract from Australian Faunal Directory (29th June, 2025)
The taxonomic history of this genus is a convoluted one, and the various species descriptions contain numerous errors and subsequent corrections. Even determining the sex of specimens has proven a challenge for taxonomists, in part due to the shape of the gaster and perhaps also the condition of the museum material (refer inventory in Leclercq, 2007).
As a further confounding factor, there appear to be relatively few specimens in collection. Assuming Leclercq gathered all the available material for the 2007 revision, that amounted to just 40 specimens in total, and nearly half of these were collected after 1954. No wonder the early taxonomic works were limited, and even Leclercq’s 2007 study cannot hope to capture the range of intraspecific variation: for Chimiloides doddii they had access to just 11 specimens, and for C. nigromaculatus just two (both male).
click to view/download latest version as a pdf (< 100kb)
Despite searching all my usual sources, I’ve yet to locate any verified images of Chimiloides. Similarly, a search on BOLD yields no results (as at 1st July 2025).
Sex differences
In Chimiloides, the morphological characters used in species-level diagnoses differ significantly between the sexes. For example, antennal shape and colour, and leg shape are useful traits in males but not females (see summary table above). Therefore, the first step in species discrimination is to determine the sex of the specimen.
As noted by Leclercq, distinguishing between the sexes in Chimiloides is a little more difficult than for many crabronids. Most notably, an accurate count of gastral segments is confounded by the shape of the gaster. So in field photos, such as iNaturalist observations, I think this method has to be discounted.
Fortunately, there are two other features that can be employed. As with most other Crabronini, males have 11 flagellar segments while females have just 10. So although the individual flagellomeres in Chimiloides are short, it will be possible to count them in some field photos.
I do always like to have a second point of reference in determining sex. For Chimiloides, the clue is orbital fovea. Females have large, oval and deep pits alongside the eyes, dorsally. No such pits are found in males.
Back to iNat observation 291696449
Despite the similarity with Ectemnius and Williamsita, I favour Chimiloides for iNaturalist obs 291696449 (sample images below) … based in large part on body colouration.
Colour pattern consistent with Chimiloides
The entirely orange gaster does not accord with any of the 13 described Ectemnius and Williamsita species (see my notes page on those genera), yet it is typical of both Chimiloides piliferus and C. doddii (see summary table above). On colour alone, C. nigromaculatus cannot be ruled out either. By my reckoning, iNaturalist obs 291696449 is a female – I can count just 10 segments in the flagellum, and there are obvious orbital fovea. And the female of C. nigromaculatus has not been discovered, so the gaster colour in that species remains unconfirmed (but see my penultimate comments).
Chimiloides doddii … most likely
iNaturalist obs 291696449 is a closer match to Chimiloides doddii than to C. piliferus, as follows:
Ocellar arrangement. The distance between the posterior ocelli (PO) is roughly equal to (perhaps even less than) the distance from the posterior ocelli to the eyes (OO). In C. piliferus, the PO is much greater than the OO.
Sculpturing of scutum. Texture appears consistent throughout, unlike C. piliferus.
Genae & base of mandible. These appear uniformly dark/black, consistent with C. doddii but in contrast C. piliferus which has densely silver lower genae and a yellow base to the mandible.
Colour of femora I. Again, the very dark base of the femora fits with C. doddii, whereas in C. piliferus it is mainly yellow.
However, one feature is a little atypical for C. doddii. All four females that Leclercq examined had yellow markings on the thorax. But there were just four examples. And for some males of C. doddii the thorax is indeed entirely black. So simply variation (?).
C. nigromaculatus remains a possibility
While possible, I think C. nigromaculatus is a less likely candidate than C. doddii. Leclercq (2007) speculates that the unknown female C. nigromaculatus will have tergites II & III more or less black, contrasting with the orange of the other tergites.
“Femelle inconnue de nigromaculatus. Je suppose : flagelle principalement noir ou brun noir; mandibule non ou peu marquée de jaune ; basitarse 1 jaune. Tergites II-III ± noirs, contrastant avec I et IV-VI orangés.” Key step 4. p.65 (Leclercq 2007).
One final caveate
Chimiloides is so morphologically similar to Williamsita and Ectemnius that I cannot be 100 per cent sure that iNat obs 291696449 does not belong to one of these latter genera. I concede that I’m putting rather a lot of weight on colouration. Having access to images of known Chimiloides would really help, so I’ll hope for digital images of museum specimens sometime soon.
References
Leclercq, J. 1951. Notes systématiques sur quelques Crabroniens (Hymenoptera Sphecidae) américains, orientaux et australiens. Bulletin & annales de la Société entomologique de Belgique 87: 31-56 (open access via California Academy of Sciences)
Leclercq, J. 1954. Monographie systématique, phylogénétique et zoogéographique des Hyménoptères Crabroniens. Les Presses de «Lejeunia», Liège. 371 pp. (open access via California Academy of Sciences)
Leclercq, J. 1974. Crabroniens d'Australie (Hymenoptera Sphecidae Crabroninae). Bulletin et Annales de la Société royale Belge d'Entomologie 110: 37–57 (open access via California Academy of Sciences)
Leclercq, J. 2007. Pour Chimiloides Leclercq, 1951, genre d’Hyménoptères Crabroniens d’Australie (Hymenoptera: Crabronidae Crabroninae). Notes Fauniques de Gembloux 60: 63–66 (open access via California Academy of Sciences)
Smith, F. 1868. Descriptions of aculeate Hymenoptera from Australia. Transactions of the Entomological Society of London 1868: 231-258
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. 1910. New fossorial Hymenoptera from Australia. Transactions of the Entomological Society of London 1910: 407-429
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.