Pompilus

Belongs within: Pompilinae.

Pompilus is one of a number of genera of spider wasps with black integument overlain with grey pubescence (Elliott 2007).

Pompilus: spider wasps of the dunes

Published 17 October 2021

I’ve commented before on the difficulties that can be attendent on identifying spider wasps (Pompilidae), one of those groups that combine a high species diversity with a tendency to be morphologically conservative. As a result, the taxonomic history of this group has been one of shifting generic concepts and ill-defined wastebaskets. Not surprisingly, one of the main victims of this uncertainty has been the type genus Pompilus. Historically used to cover a significant percentage of all spider wasps, the name Pompilus is now restricted to a small cluster of species inhabiting the Old World.

The genus Pompilus and its history were last revised in detail by Day (1981) who recognised seven species associated with more or less open, sandy habitats. The most widespread and best-known of these is Pompilus cinereus, found over wide parts of Eurasia, Africa and Australia, often alongside bodies of water. This species shows a wide range of morphological variation across its range but Day (1981) declared himself unable to sensibly correlate this variation with discrete populations. The possibility remains that further studies may identify P. cinereus as a species complex. The other species in the genus, P. mirandus of India and south-east Asia and five African species, are more restricted in range and little studied. Pompilus mirandus is more tolerant of vegetated habitats than P. cinereus. Conversely, P. niveus of northern Africa is a specialist of the sand dunes of the Sahara Desert. Species of Pompilus all have a black cuticle with a covering of short grey pubescence. The most distinctive feature of the genus is the possession by females of long, weakly curved mandibles with a single inner tooth (other spider wasps have shorter, thicker mandibles with more teeth). These modified mandibles are related to their distinctive manner of handling prey. Whereas other spider wasps will drag their spider victims backwards to their nest, females of Pompilus will lift the spider off the ground and run forward while carrying it.

Nesting behaviour has only been described for P. cinereus. Targeted prey comprises ground-running spiders such as wolf spiders or clubionids. After a spider has been captured, paralysed and carried near the intended nest site, it is temporarily buried in the sand while the female constructs a burrow (Day suggested that this preliminary burial was to prevent the spider being stolen). The simple burrow leads to a single nest cell a few inches deep. The female exhumes the spider, transports it into the burrow and then lays an egg on its abdomen near the front of the side. She then closes the entrance to the burrow with sand, tamping it down securely with the end of her metasoma.

Within the burrow, the spider begins to wake from its paralysis after a few hours. However, it remains in poor shape: its movements are slow and it begins to continuously exude silk from its spinnerets. By wandering about the cell in this distressed state, the spider ends up producing a silken purse that serves as extra protection for the nest’s contents. This, of course, includes the wasp larva that within a couple of days will have begun to feed on the trapped spider.

Though details of breeding behaviour have not been observed for other Pompilus species, they might be expected to resemble P. cinereus. It might be noted, however, that the female of P. cinereus has a patch of flattened scales at the end of the metasoma that is less developed in P. mirandus. Is this an indication that P. mirandus is somehow less conscientious in sealing the nest burrow than P. cinereus? If you keep an eye out in the wastelands of India, you might just learn the answer.

Systematics of Pompilus

Pompilus Fabricius 1798 [incl. Chionopompilus Priesner 1955]E07
    |--P. cinereus (Fabricius 1775) (see below for synonymy)E07
    |--P. aculeatusR13
    |--P. apicalisR13
    |--P. aterrimusMS01
    |--P. audax Westwood 1842E07
    |--P. bifasciatus Meunier 1915EG06
    |--P. caerulescens Dalla Torre 1897 [=P. caeruleus Smith 1879 non Taschenberg 1869]E07
    |--P. campestrisMS01
    |--P. cinctellusR26
    |--P. coccineusR13
    |--P. crassitarsisR13
    |--P. csikianus Kohl in Mocsáry & Szépligeti 1901MS01
    |--P. decemguttatusR26
    |--P. effodiensR13
    |--P. fasciatellusR26
    |--P. flavicornis Smith 1855E07
    |--P. fumipennisMS01
    |--P. fuscusR26
    |--P. gibbusL49
    |--P. guttaR26
    |--P. holomelasR13
    |--P. induratus Heer 1849EG06
    |--P. infandus Smith 1868E07
    |--P. lugubris Smith 1868E07
    |--P. lunulatus (Saussure 1867) (see below for synonymy)E07
    |--P. marginatusR13
    |--P. natalensisR13
    |--P. nigerrimusR13
    |--P. niveus Saunders 1901 [incl. *Chionopompilus rabinovitchi Priesner 1955]E07
    |--P. pectinipesR13
    |--P. pictifrons Smith 1855E07
    |--P. plicatusR13
    |--P. pyrenaeusL49
    |--P. quinquenotatusR13
    |--P. rufipesR13
    |--P. sanguinicolor Dalla Torre 1897 [=P. sanguinolentus Smith 1879 non Fabricius 1793]E07
    |--P. sclerosus Meunier 1917EG06
    |--P. spissusR13
    |--P. taiwanus Tsuneki 1989T89
    |--P. tripunctatusMS01
    |--P. trivialisMS01
    |--P. unguicularisR13
    |--P. vagansR13
    `--P. viaticusMS01

Pompilus cinereus (Fabricius 1775) [=Sphex cinerea; incl. Pompilus ami Tsuneki 1989, Pompilus argyrostoma Stephens 1829 (n. n.), Psammochares bilineatus Arnold 1937, Sericopompilus bivittatus Banks 1934, Pompilus bivittatus, Pompilus bunun Tsuneki 1989, Pompilus chevrieri Tournier 1889, Pompilus plumbeus chevrieri, Aporoideus clarus Banks 1941, Pompilus plumbeus gotlandicus Wolf 1972, Pompilus ithonus Cameron 1908, Psammochares latilabris Arnold 1937, Pompilus leprosus Dalla Torre 1897, Pompilus plumbeus lusitanicus Wolf & Dinz 1970, Pompilus plumbeus lucitanicus (l. c.), Psammochares plumbeus maroccana Nadig & Nadig 1935 (n. n.), Pompilus pulcher placidus Priesner 1968 (nom. inv.), Sphex plumbea Fabricius 1787, Ferreola plumbea, Pepsis plumbea, Pompilius (l. c.) plumbeus, Pompilus plumbea, Pompilus plumbeus, Psammochares plumbeau (l. c.), Ps. plumbeus, Pompilus plumbeicolor Dalla Torre 1897, Pompilus pruinosus Smith 1879 non Smith 1855, *Pompilus pulcher Fabricius 1798, Pompilus plumbeus pulcher, Psammochares plumbeus pulchra, Pompilus sericeibalteatus Cameron 1910, Pompilus tsou Tsuneki 1989]^E07

Pompilus lunulatus (Saussure 1867) [=Pogonius lunulatus, Agenia lunulata, Deuteragenia lunulata, Pseudagenia lunulata; incl. Pompilus spectrum Kohl 1886]^E07

*Type species of generic name indicated

References

Day, M. C. 1981. A revision of Pompilus Fabricius (Hymenoptera: Pompilidae), with further nomenclatural and biological considerations. Bulletin of the British Museum (Natural History): Entomology 42 (1): 1–42.

[E07] Elliott, M. G. 2007. Annotated catalogue of the Pompilidae (Hymenoptera) of Australia. Zootaxa 1428: 1–83.

[EG06] Engel, M. S., & D. A. Grimaldi. 2006. The first Cretaceous spider wasp (Hymenoptera: Pompilidae). Journal of the Kansas Entomological Society 79 (4): 359–368.

[L49] Lucas, H. 1849. Exploration Scientifique de l’Algérie pendant les années 1840, 1841, 1842 publiée par ordre du gouvernement et avec le concours d’une commission académique. Sciences physiques. Zoologie. II. Histoire naturelle des animaux articulés. Troisième partie. Insectes (suite). Imprimerie Nationale: Paris.

[MS01] Mocsáry, A., & V. Szépligeti. 1901. Hymenopterák [Hymenopteren]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 121–169. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.

[R13] Reuter, O. M. 1913. Lebensgewohnheiten und Instinkte der Insekten bis zum Erwachen der sozialen Instinkte. R. Friedländer & Sohn: Berlin.

[R26] Risso, A. 1826. Histoire naturelle des principales productions de l’Europe méridionale et particulièrement de celles des environs de Nice et des Alpes maritimes vol. 5. F.-G. Levrault: Paris.

[T89] Tsuneki, K. 1989. A study on the Pompilidae of Taiwan (Hymenoptera). Special Publications of the Japan Hymenopterists Association 35: 1–180.