Belongs within: Crabronini.
The subgenus Echuca of the genus Podagritus is an Australian group of wasps, distinguished from other members of the genus by a flat prepectus and low metapleuron (Bohart & Menke 1976).
Podagritus in Australia
Published 31 October 2020
The digger wasps of the tribe Crabronini are a widespread group distinguished by a boxy head shape and relatively stout mesosoma. They are not dissimilar to hairless bees and indeed are close relatives of that group. There is a wide diversity of crabronins around the world; among their representatives here in Australia are members of the genus Podagritus.
Podagritus species are medium-sized, elongate crabronins, generally in the region of a centimetre in length (give or take a few millimetres). The gaster is pedunculate (that is, the first segment of the metasoma is drawn into an elongate peduncle). Other, finer features distinguishing them from related genera of crabronins include a palpal formula of 5-3 (referring to the number of segments in the maxillary and labial palps, respectively; 5-3 indicates that both palps are slightly reduced from the ancestral count for crabronins) and often the presence of a sharp subvertical ridge, the omaulus, near the front of the mesopleuron (the median plate on the side of the mesosoma). If the omaulus is not present as such, there is still a distinct curve where it would have been so the planes of the mesopleuron on either side are more or less perpendicular. Females have a well defined triangular, flat pygidial plate and males often have one as well (Bohart & Menke 1976).
Thirty species of Podagritus were recognised from Australia by Leclercq (1998). Other species of the genus are known from New Zealand and South America. Historically, the Australian species have been treated as a distinct subgenus Echuca from Podagritus elsewhere, based on features such as a well defined, flat prepectus and a weakly sculpted metapleuron. Leclercq, however, questioned the value of this distinction, noting the existence of a couple of Australian species sharing notable features in common with species found elsewhere, and suggested abandoning subgenera until the genus could be revised as a whole.
The natural history of Podagritus species in Australia remains poorly known. One species found in the east of the continent, P. leptospermi, has been found nesting in a sloping gravel bank (Bohart & Menke 1976). Burrows were near vertical and close to a foot deep, and contained two or three cells placed at the ends of lateral galleries (one cell per gallery). Entrances were surrounded by flat mounds of sand six to ten centimetres wide and were not closed while the female was out hunting. Cells were stocked with flies (Tachinidae and Therevidae, so presumably reasonably large) that were initially stored at the bottom of the burrow before being placed in the cell head inwards and belly up, in lots of four to six. The egg was attached to a fly between the head and thorax, so when the larva hatched it would find itself already in place on a welcoming bed of food.
Systematics of Podagritus (Echuca)
Characters (from Bohart & Menke 1976): Moderate sized, elongate forms; eyes bare, inner orbits convergent below; scapal basin ecarinate dorsally; antennal sockets close to each other and to orbits; male antenna with 13 articles, scape ecarinate: palpal formula 5-3; mandible with externoventral margin entire; propleura simple; scutum, axillae, scutellum and metanotum simple; prepectus flat, separated from pre-omaular area by an omaulus or by a different in plane; acetabular carina, mesopleuraulus and sternaulus absent; metapleuron plainly depressed below level of mesopleuron and propodeum, not gibbose; hindwing jugal lobe about as long as submedian cell; gaster pedunculate; female pygidial plate well defined, nearly flat, triangular, punctate.
<==Podagritus (Echuca Pate 1944)C85
|--P. (*E.) tricolor (Smith 1856) [=Crabro tricolor; incl. C. (Rhopalum) militaris Turner 1908]C85
|--P. (E.) alevinus Leclercq 1957C85
|--P. (E.) aliciae (Turner 1915) [=Rhopalum aliciae]C85
|--P. (E.) anerus Leclercq 1955C85
|--P. (E.) australiensis Tsuneki 1977C85
|--P. (E.) burnsi Leclercq 1955C85
|--P. (E.) carolus Leclercq 1955C85
|--P. (E.) cornigerum (Tsuneki 1977) [=Rhopalum cornigerum]C85
|--P. (E.) cygnorum (Turner 1915) [=Rhopalum cygnorum]C85
|--P. (E.) doreeni Leclercq 1955C85
|--P. (E.) edgarus Leclercq 1957C85
|--P. (E.) imbelle (Turner 1915) [=Rhopalum tricolor imbelle]C85
|--P. (E.) kiatae Leclercq 1955C85
|--P. (E.) krombeini Leclerq 1955C85
|--P. (E.) leptospermi (Turner 1915) [=Rhopalum leptospermi]C85
|--P. (E.) marcellus Leclercq 1955C85
|--P. (E.) mullewanus Leclercq 1970C85
|--P. (E.) peratus Leclercq 1955C85
|--P. (E.) rieki Leclercq 1957C85
|--P. (E.) rufotaeniatus (Kohl 1905) [=Crabro rufotaeniatus; incl. P. getricus Leclercq 1957]BM76
|--P. (E.) valdiviae Leclercq 1951 [incl. P. almagrus Leclercq 1957]BM76
`--P. (E.) yarrowi Leclercq 1955C85
*Type species of generic name indicated
References
[BM76] Bohart, R. M., & A. S. Menke. 1976. Sphecid Wasps of the World. University of California Press: Berkeley.
[C85] Cardale, J. C. 1985. Vespoidea and Sphecoidea. In: Walton, D. W. (ed.) Zoological Catalogue of Australia vol. 2. Hymenoptera: Formicoidea, Vespoidea and Sphecoidea pp. 150–303. Australian Government Publishing Service: Canberra.
Leclercq, J. 1998. Hyménoptères sphécides crabroniens d’Australie du genre Podagritus Spinola, 1851 (Hymenoptera, Sphecidae). Entomofauna 19 (18): 285–308.