Megalyridae
Encyclopedia
Megalyroidea is a small Hymenoptera
n superfamily that includes a single family, Megalyridae, with 8 genera (plus 3 extinct ones) and at least 45 extant species. Modern megalyrids are found mostly in areas of relict
primary tropical forests, and there are very few New World
representatives. The most abundant and species rich megalyrid fauna is in Australia
. Another peak of diversity appears to be in the relict
forests of Madagascar
, but most of these species are still undescribed.
Historically there has been much confusion about the definition of this family. Species now placed in Megalyridae have in the past been classified into as many as six other families (Braconidae
, Evaniidae
, Ichneumonidae
, Stephanidae
, as well as Dinapsidae and Maimetshidae, the latter two both now considered ranks within the Megalyridae).
The best defining feature, unique to the family, is that the mesothoracic
spiracle
has moved, and is actually located in the upper corner of the pronotum, though this is a fairly obscure feature to see. Perhaps the most useful visible character is that the base of the antenna fits into a wide concave groove below the eye, though a few other wasp families exhibit this trait. Females of Megalyra have ovipositors ranging from 5-8 times the body length, but this is not true of the other genera.
The largest known megalyrid is the female of the Australia
n Megalyra shuckardi, with a body length of 22 mm and ovipositor
length of 82 mm. The smallest known megalyrid is the Brazil
ian Cryptalyra plaumanni, with a body length of 2.9 mm and ovipositor 1 mm long.
Megalyrid wasps are thought to be idiobiont endoparasitoids of concealed insect larvae. One Australian species, Megalyra troglodytes, attacks the larvae of Arpactophilus mimi, a mud-nesting crabronid wasp
. Oviposition habits of Megalyridae are regarded as quite primitive, with field observations suggesting that they simply poke their ovipositor into pre-existing cavities, holes, or cracks, rather than drilling into the substrate as in other Apocrita
.
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
n superfamily that includes a single family, Megalyridae, with 8 genera (plus 3 extinct ones) and at least 45 extant species. Modern megalyrids are found mostly in areas of relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
primary tropical forests, and there are very few New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
representatives. The most abundant and species rich megalyrid fauna is in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. Another peak of diversity appears to be in the relict
Relict
A relict is a surviving remnant of a natural phenomenon.* In biology a relict is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas....
forests of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, but most of these species are still undescribed.
Historically there has been much confusion about the definition of this family. Species now placed in Megalyridae have in the past been classified into as many as six other families (Braconidae
Braconidae
Braconidae is a family of parasitoid wasps and one of the richest families of insects. Between 50,000 and 150,000 species exist worldwide. The species are grouped into about 45 subfamilies and 1,000 genera, some important ones being: Ademon, Aphanta, Asobara, Bracon hebetor, Cenocoelius, Chaenusa,...
, Evaniidae
Evaniidae
Evaniidae, also known as the ensign wasps or hatchet wasps, is a family of parasitic wasps. It numbers around 20 extant genera containing over 400 described species, and is found all over the world except in the polar regions...
, Ichneumonidae
Ichneumonidae
Ichneumonidae is a family within the insect order Hymenoptera. Insects in this family are commonly called ichneumon wasps. Less exact terms are ichneumon flies , or scorpion wasps due to the extreme lengthening and curving of the abdomen...
, Stephanidae
Stephanidae
Stephanoidea is a small Hymenopteran superfamily that includes a single extant family, Stephanidae with 9 genera and almost 300 species, primarily tropical and subtropical in distribution...
, as well as Dinapsidae and Maimetshidae, the latter two both now considered ranks within the Megalyridae).
The best defining feature, unique to the family, is that the mesothoracic
Mesothorax
The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. Its principal sclerites are the mesonotum , the mesosternum , and the mesopleuron on each side...
spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
has moved, and is actually located in the upper corner of the pronotum, though this is a fairly obscure feature to see. Perhaps the most useful visible character is that the base of the antenna fits into a wide concave groove below the eye, though a few other wasp families exhibit this trait. Females of Megalyra have ovipositors ranging from 5-8 times the body length, but this is not true of the other genera.
The largest known megalyrid is the female of the Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n Megalyra shuckardi, with a body length of 22 mm and ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
length of 82 mm. The smallest known megalyrid is the Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
ian Cryptalyra plaumanni, with a body length of 2.9 mm and ovipositor 1 mm long.
Megalyrid wasps are thought to be idiobiont endoparasitoids of concealed insect larvae. One Australian species, Megalyra troglodytes, attacks the larvae of Arpactophilus mimi, a mud-nesting crabronid wasp
Crabronidae
Crabronidae is a large family of wasps, that includes nearly all of the species formerly comprising the now-defunct superfamily Sphecoidea. It collectively includes well over 200 genera, containing well over 9000 species. Crabronids were originally a part of Sphecidae, but the latter name is now...
. Oviposition habits of Megalyridae are regarded as quite primitive, with field observations suggesting that they simply poke their ovipositor into pre-existing cavities, holes, or cracks, rather than drilling into the substrate as in other Apocrita
Apocrita
Apocrita is a suborder of insects in the order Hymenoptera.Apocrita includes wasps, bees and ants, and consists of many families. It includes the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" formed between the first two segments of the actual abdomen; the...
.