Head and mesosoma in lateral view of Aclastus, from Gauld (1984).

Belongs within: Ichneumonidae.
Contains: Paraphylax, Gelis.

The Phygadeuontini are a diverse group of ichneumon wasps, most species of which are small with two bullae in the forewing vein 2m-cu. Some species have only a single bulla, but are also uniformly blackish with wings less than five millimetres in length (Gauld 1984).

Ant-like ichneumons
Published 15 March 2015
Female Gelis, copyright Krister Hall.

The ichneumons are one of the best-known groups of parasitoid wasps. The most familiar ichneumons are relatively large for parasitoid wasps, and sometimes even for wasps in general. This can make them somewhat intimidating in appearance, especially considering the likelihood of the long ovipositor of a female being mistaken for a sting by those not in the know. However, not all ichneumons are giants. The photo above shows a tiny ichneumon of the genus Gelis, females of which are wingless and bear a distinct superficial resemblance to ants. This resemblance is likely to afford them some protection from potential predators, and at least one Gelis species, G. agilis, has been shown to release a chemical when threatened very similar to the alarm pheromones of the black garden ant Lasius niger (Malcicka et al. 2015). On the other hand, one might be tempted to wonder if this mimicry may sometimes serve a more nefarious purpose: another species, G. apterus, has been recorded as a parasitoid of the ant-eating spider Zodarion styliferum (Korenko et al. 2013). However, G. apterus has not been recorded to use its ant appearance to lure its host; instead, the female ichneumon uses its ovipositor to pierce the igloo-like silken retreat that the spider occupies during the day. Other species of Gelis are known to be parasitoids of moth cocoons rather than spiders (Gauld 1984), so Gelis‘ status as an ant-mimic and its choice of host may be simple coincidence.

Phygadeuon exiguus, copyright James K. Lindsey.

Gelis belongs to a world-wide tribe of ichneumons known as the Phygadeuontini (sometimes referred to in older sources as the Gelini), a diverse group including well over 100 genera. Most, but not all, phygadeuontins are also among the smaller ichneumons. The range of hosts attacked by the group is equally diverse, including (among others) moths and lacewing pupae, and spider egg sacs, while some are hyperparasitoids on the pupae of other parasitoid wasps (Gauld 1984). Species of the genus Phygadeuon include parasitoids of wood-burrowing beetles that use the enlarged ends of their antennae to tap at wood in search of hollow burrows within. Some phygadeuontins are external parasitoids, while others are endoparasitoids. The larvae of Gelis apterus can even be regarded as true predators, as they attack not the eggs of their host but its newly-hatched spiderlings (Korenko et al. 2013). A common theme between these diverse hosts, though, is the production by most of them of silken cocoons or other protective structures that the female phygadeuontin is able to pierce with her ovipositor.

Systematics of Phygadeuontini
Phygadeuontini [Gelini]G84
| |--Mastrus carpocapsaeG84, R96
| |--HelcostizusG84
| `--Aclosmation Gauld 1984G84
| `--*A. rufum Gauld 1984G84
| |--Chirotica decorataG84
| |--Asmenophylax Gauld 1984G84
| | `--*A. minutus Gauld 1984G84
| |--Handaoia Seyrig 1952G84
| | `--*H. spinosa Seyrig 1952G84
| |--Lienella Cameron 1903 [incl. Marakelia Seyrig 1952]G84
| | |--*L. nigripes Cameron 1905G84
| | `--*Marakelia’ albatoria Seyrig 1952G84
| `--Astomaspis Foerster 1869 (see below for synonymy)G84
| |--*A. metathoracicaG84
| |--*Syrites’ acanthogaster Tosquinet 1903G84
| |--A. froggattiG84
| |--A. ruficollis (Cameron 1900) [=*Caenopimpla ruficollis]G84
| |--A. ruficornisG84
| |--*Caenoaulax’ striatus Cameron 1905G84
| |--A. striola [incl. *Camptolynx striatus Cameron 1911]G84
| `--*Acanthoprymnus’ violaceipennis Cameron 1905G84
|--Amblyaclastus Gauld 1984G84
| `--*A. melanops Gauld 1984G84
|--Glyphaclastus Gauld 1984G84
| `--*G. uvulus Gauld 1984G84
|--Austriteles Gauld 1984G84
| `--*A. armatorius Gauld 1984G84
|--Aclastus Foerster 1869 [=Microplex Foerster 1869; incl. Daetora Foerster 1869, Opisthostenus Foerster 1869]G84
| |--*A. rufipes [=*Microplex rufipes]G84
| |--‘Hemiteles’ etorofuensis [=*Opisthostenus etorofuensis]G84
| `--‘Hemiteles’ solutus [=*Daetora soluta]G84
|--H. areatorRD77
|--H. crassicornisMS01
|--H. limbatusMS01
|--H. rufipleuris Szépligeti in Mocsáry & Szépligeti 1901MS01
|--H. sibiricus Szépligeti in Mocsáry & Szépligeti 1901MS01
`--H. thyridopterigis [=Allocota thyridopterigis]B37

Phygadeuontini incertae sedis:
Meringops Townes 1970G84
`--*M. minipes Townes 1970G84
Rhadinomastrus Gauld 1984G84
`--*R. elongatus Gauld 1984G84
Xenolytus Foerster 1869 [incl. Sternocryptus Roman 1925]G84
`--X. bitinctus (see below for synonymy)G84
Nipponaetes Uchida 1933 [incl. Potia Seyrig 1952, Thalops Townes 1958]G84
|--*N. haeussleri (Uchida 1933) [=Hemiteles (*Nipponaetes) haeussleri]G84
|--*Thalops’ fessus Townes 1958G84
`--*Potia’ inelegans Seyrig 1952G84
Tryonocryptus Gauld & Holloway 1983G84
|--*T. nigridorsalis Gauld & Holloway 1983G84
|--T. amicusG84
`--T. gigasG84
|--P. annulicornisMS01
|--P. csikii Szépligeti in Mocsáry & Szépligeti 1901MS01
|--P. dumetorumGWB02
`--P. lucidus Szépligeti in Mocsáry & Szépligeti 1901MS01
Dichrogaster Doumerc 1855 (see below for synonymy)G84
|--‘Hemiteles’ aestivalis (see below for synonymy)G84
|--‘Otacustes’ chrysopae [incl. *O. atriceps, *Chrysopoctonus atriceps]G84
|--*Microtorus’ kichijoiG84
`--‘Hemiteles’ longicaudatus [=*Xenobrachys longicaudatus]G84
Isdromas Foerster 1869 [incl. Daictimorpha Viereck 1912, Larsephna Cameron 1903, Phatnacra Foerster 1869]G84
|--‘Hemiteles’ lycaenae [incl. Acrolyta aletiae, *Isdromas aletiae]G84
|--I. granulatus Gauld 1984G84
|--‘Hemiteles’ monterai [=*Phatnacra monterai]G84
|--I. paternicus Gauld 1984G84
|--*Daictimorpha’ peruviana Viereck 1912G84
|--*Larsephna’ varipes Cameron 1903G84
`--I. yuendumui Gauld 1984G84

Astomaspis Foerster 1869 [incl. Acanthoprymnus Cameron 1905, Caenoaulax Cameron 1905, Caenopimpla Cameron 1900, Camptolynx Cameron 1911, Syrites Tosquinet 1903]G84

Dichrogaster Doumerc 1855 [incl. Brachycephalus Foerster 1869 non Fitzinger 1826, Brachycranium Ashmead 1900, Chrysopoctonus Cushman 1919, Microtorus Foerster 1869, Otacustes Foerster 1869, Xenobrachys Foerster 1869]G84

‘Hemiteles’ aestivalis [=*Brachycephalus aestivalis, *Brachycranium aestivale; incl. Microgaster perlae, *Dichrogaster perlae]G84

Xenolytus bitinctus [=Ichneumon bitinctus, Cryptus bitinctus, *Sternocryptus bitinctus; incl. *Xenolytus rufipes]G84

*Type species of generic name indicated


[B37] Balduf, W. V. 1937. Bionomic notes on the common bagworm, Thyridopteryx ephemeraeformis Haw., (Lepid., Psychidae) and its insect enemies (Hym., Lepid.). Proceedings of the Entomological Society of Washington 39 (7): 169–184.

[G84] Gauld, I. D. 1984. An Introduction to the Ichneumonidae of Australia. British Museum (Natural History).

[GWB02] Gauld, I. D., D. B. Wahl & G. R. Broad. 2002. The suprageneric groups of the Pimplinae (Hymenoptera: Ichneumonidae): a cladistic re-evaluation and evolutionary biological study. Zoological Journal of the Linnean Society 136: 421–485.

Korenko, S., S. Schmidt, M. Schwarz, G. A. P. Gibson, & S. Pekár. 2013. Hymenopteran parasitoids of the ant-eating spider Zodarion styliferum (Simon) (Araneae, Zodariidae). Zookeys 262: 1–15.

Malcicka, M., T. M. Bezemer, B. Visser, M. Bloemberg, C. J. P. Snart, I. C. W. Hardy & J. A. Harvey. 2015. Multi-trait mimicry of ants by a parasitoid wasp. Scientific Reports 5: 8043. doi:10.1038/srep08043.

[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.

[RD77] Richards, O. W., & R. G. Davies. 1977. Imms’ General Textbook of Entomology 10th ed. vol. 2. Classification and Biology. Chapman and Hall: London.

[R96] Roff, D. A. 1996. The evolution of threshold traits in animals. Quarterly Review of Biology 71 (1): 3–35.

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