Megischus is a genus of crown-wasps in the parasitoid family

Stephanidae The Stephanidae, sometimes called crown wasps, are a family (biology), family of parasitoid wasps. They are the only living members of the superfamily Stephanoidea. Stephanidae has at least 345 living species in 11 genera. The family is considere ...

. There are over 90 species globally distributed throughout the

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

Palearctic The Palearctic or Palaearctic is a biogeographic realm of the Earth, the largest of eight. Confined almost entirely to the Eastern Hemisphere, it stretches across Europe and Asia, north of the foothills of the Himalayas, and North Africa. Th ...

Afrotropical The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...

Oriental The Orient is a term referring to the East in relation to Europe, traditionally comprising anything belonging to the Eastern world. It is the antonym of the term ''Occident'', which refers to the Western world. In English, it is largely a meto ...

Australasian Australasia is a subregion of Oceania, comprising Australia, New Zealand (overlapping with Polynesia), and sometimes including New Guinea and surrounding islands (overlapping with Melanesia). The term is used in a number of different contexts, ...

, and

Oceanian Oceania ( , ) is a geographical region including Australasia, Melanesia, Micronesia, and Polynesia. Outside of the English-speaking world, Oceania is generally considered a continent, while Mainland Australia is regarded as its continenta ...

zoogeographical regions. Members of the family Stephanidae are notorious for their distinct “crown” composed of 5 spike-shaped tubercles on the head. The ''Megischus'' genus can be distinguished from other genera in Stephanidae by transversely depressed hind tibia and the absence of setae on the M+Cu1 vein. Adult individuals of this species can reach up to 40 millimeters in length. Females possess an ovipositor that exceeds their body length and is used to lay eggs in species of wood-boring beetle families including

Buprestidae Buprestidae is a family (biology), family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy Iridescence, iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the lar ...

(

Jewel Beetle Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers. The family is among the largest of the beetles, with some ...

s),

Cerambycidae The longhorn beetles (Cerambycidae), also known as long-horned or longicorns (whose larvae are often referred to as roundheaded borers), are a large family of beetles, with over 35,000 species described. Most species are characterized by anten ...

(

Longhorned Beetle The longhorn beetles (Cerambycidae), also known as long-horned or longicorns (whose larvae are often referred to as roundheaded borers), are a large family of beetles, with over 35,000 species described. Most species are characterized by anten ...

s), and

Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. Th ...

(

True Weevil The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae ...

s). Due to their specialized parasitic lifestyle, ''Megischus'' plays a critical role in regulating the wood-boring beetle population, which can be pests for species of hardwood trees and other vegetation worldwide. In addition to beetles, some species in ''Megischus'' are parasitoids of Hymenopteran species that include species of

Siricidae Horntails or wood wasps are any of the 150 non-social species of the hymenopteran family Siricidae, a type of wood-eating sawfly. The common name "horntail" derives from the stout, spine-like structure at the end of the adult's abdomen which is ...

and solitary

Apoidea The superfamily Apoidea is a major group (of over 30 000 species) within the Hymenoptera, which includes two traditionally recognized lineages, the "sphecoid" wasps, and the bees. Molecular phylogeny demonstrates that the bees arose from ...

Taxonomy

''Megischus'' is a genus of crown wasp. It was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

Gaspard Auguste Brullé Gaspard Auguste Brullé (7 April, 1809 – 21 January, 1873) was a French entomologist. Passionate about insects from a young age and through the intervention of Georges Cuvier, he participated in the Morea expedition organised by Jean Baptiste ...

in 1846. The genus has a

cosmopolitan distribution In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...

, and over ninety species are recognized. It is the

type genus In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name. Zoological nomenclature According to the International Code of Zoological Nomenclature, "The name-bearin ...

of the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Megischini, subfamily Stephaninae, family

; the other genera in this tribe are '' Hemistephanus'' and '' Pseudomegischus''.

Description & Etymology

Members of the family

have a distinct “crown” composed of 5 spike-shaped tubercles on the head.Genus Megischus
BugGuide.net The ''Megischus'' genus can be distinguished from other genera in Stephanidae by transversely depressed hind tibia and the absence of setae on the M+Cu1 vein. Adults are typically a black or brown color and can range from approximately 10–30 mm long depending on the species (and excluding the ovipositor), with males slightly larger than females in size. The name “Megischus” is derived from the Greek word suffix ''mega'' meaning large and the word ''ischi'' for hip joint.

Identification Characteristics

Other characteristics to identify ''Megischus'' include: * Sub-spherical head with a crown of tubercles * Filiform antennae, not elbowed, typically with numerous divisions (12-44) * Metasoma petiole very long, inserted in a lower area between the hind coxae * Wide and toothed hind femur on its ventral margin * Long ovipositor, typically slightly longer than the body (only present in females) * Anterior wings without a costal cell, or if present, very narrow * At most with 3 cubital cells where the last one (c3) is open * Tarsi without plantar lobes

Natural History

Life Cycle & Behavior

Specimens of ''Megischus'' are significantly more likely to be found during the summer with peak appearances occurring at the 26th week of the year. ''Megischus'' are ectoparasitoids that play a critical role in regulating the wood-boring beetle population, which can be pests for species of hardwood trees and other vegetation worldwide. Adult females spend hours boring their ovipositors into wood to lay their eggs onto host larvae inside the wood. Members of the genus often target wood-boring beetle families including

(Jewel Beetles),

(Longhorned Beetles), and

(True Weevils). The female has chemosensors and a chordotonal organ to detect vibrations in order to determine a suitable host where she can lay her eggs. After developing, emerging adults chew their way out of the wood. Interestingly, males emerge several days before females. They are diurnal.

Habitat

The distribution of ''Megischus'' largely mimics the distribution of hardwood trees, including oak, pine, mesquite, mangrove, and a variety of other groups that host wood-bearing Coleopteran families.

Historic & Current Distribution

There are over 90 species globally distributed throughout the Neotropical, Paleartic, Afrotropical, Oriental, and Australasian and Oceanian zoogeographical regions. The majority of species of ''Megischus'' can be found in the Neotropical and Oriental regions.

Conservation Status

''Megischus'' is not considered endangered or at risk. However, more research is necessary to assess the conservation status of all species, given the global distribution and large diversity of the genus.

References

{{Taxonbar, from=Q18595266 Stephanoidea Hymenoptera genera