Trigonalidae is a family of parasitic wasps in the suborder

Apocrita Apocrita is a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" ( petiole) formed ...

. They are the only living members of the superfamily Trigonaloidea. Trigonalidae are divided into 2 subfamilies; Orthogonalinae and Trigonalinae. These wasps are extremely rare, but surprisingly diverse, with over 90 species in 16 genera, and are known from all parts of the world.Trigonalidae Website
/ref> It is possibly the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to all

Aculeata Aculeata is an infraorder of Hymenoptera containing ants, bees, and stinging wasps. The name is a reference to the defining feature of the group, which is the modification of the ovipositor into a stinger. However, many members of the group cann ...

Ecology

What little is known about the biology of these insects indicates a remarkably improbable life history: in nearly all known species, females lay thousands of minute eggs, "clamping" them to the edges of, or injecting them inside leaves. The egg must then be consumed by a

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder ...

. Once inside the caterpillar, the trigonalid egg either hatches and attacks any other

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

larvae (including its siblings) in the caterpillar, or it waits until the caterpillar is killed and fed to a vespid larva, which it then attacks. If the caterpillar is neither attacked by another parasitoid nor fed to a vespid, the trigonalid larva fails to develop. Therefore, they are

s or

hyperparasitoid A hyperparasite, also known as a metaparasite, is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two othe ...

s, but in a manner virtually unique among the insects, in that the eggs must be swallowed by a host, and even more unusual in that there may be an

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include ...

. A few species are known exceptions, which directly parasitise

sawflies Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plant ...

Nomenclature

The name of this family has also been spelled "Trigonaloidae" and "Trigonalyidae". These are unjustified emendations of the name and incorrect under Article 29.5 of the

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...

.ICZN Code
29.5. Maintenance of current spellings. If a spelling of a family-group name was not formed in accordance with Article 29.3 but is in prevailing usage, that spelling is to be maintained, whether or not it is the original spelling and whether or not its derivation from the name of the type genus is in accordance with the grammatical procedures in Articles 29.3.1 and 29.3.2. Despite this, some authors have continued to use the latter, "Trigonalyidae" spelling.

Taxonomy

The fossil record of the family is poor, and there are no confirmed members of the family prior to the

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

, with the oldest being from the

Ypresian In the geologic timescale the Ypresian is the oldest age (geology), age or lowest stage (stratigraphy), stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by th ...

Eocene Okanagan Highlands in western North America. A possible specimen is known from the mid-Cretaceous

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...

of Myanmar, but this differs substantially from modern members of the family, and may belong to the

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

. Suggested relatives of Trigonalidae within Trigonaloidea include the extinct family Maimetshidae, known from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period.

Genera

* '' Afrigonalys'' * '' Bakeronymus'' * '' Bareogonalos'' * '' Eotrigonalis'' * '' Ischnogonalos'' * '' Jezonogonalos'' * '' Lycogaster'' * '' Mimelogonalos'' * '' Nomadina'' * '' Orthogonalys'' * ''

Pseudogonalos ''Pseudogonalos'' is a genus of parasitic wasps belonging to the family Trigonalidae. Members of these genus vary from 5.5mm to 13.9mm in length. Species Species include: * ''Pseudogonalos angusta'' Schulz, 1906 * ''Pseudogonalos hahnii'' (Spi ...

'' * '' Pseudonomadina'' * '' Seminota'' * '' Taeniogonalos'' * '' Teranishia'' * '' Trigonalys'' * '' Xanthogonalos''

References

Notes

{{Authority control Parasitica Apocrita families