Pachynomidae is a family of

true bugs Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising more than 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, Cimex, bed bugs, and shield bugs. They ...

within the suborder

Cimicomorpha The Cimicomorpha are an infraorder of insects in the order Hemiptera, the true bugs. The Rostrum (anatomy), rostrum and other Morphology (biology), morphology of some members apparently is adapted to feeding on animals as their prey or host (biol ...

. 23 species in 5 genera are known.

Morphology

Pachynomidae range in size from 3.5 to 11 millimetres and often bear a certain resemblance to sickle bugs (

Nabidae The insecta, insect family (biology), family Nabidae contains the damsel bugs. There are over 500 species in 20 genera. They are soft-bodied, elongate, winged terrestrial predators. Many damsel bugs catch and hold prey with their forelegs, sim ...

) from the subfamily Prostemmatinae. The upper surface of their bodies varies from very shiny (genus '' Pachynomus'' ) to matte and hairless to heavily hairy. The

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

are large, and the head has no constriction behind the compound eyes.

Ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

can be present or absent. The antennae appear to have five segments, with the second segment (pedicellus) divided into two parts. The distal part of the pedicellus usually bears a single trichobothrium. The labium is thick and strongly curved. The thighs (femora ) of the forelegs are greatly enlarged, and the shins (tibiae) of the forelegs bear ''fossulae spongiosae'' (specialised hairy structures used for holding on). The eighth abdominal segment of the males is reduced and retracted into the seventh segment. Male genitalia are symmetrical, the pygophore is well developed and apically articulated into the abdomen. The

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...

of the females is plate-shaped. A

spermatheca The spermatheca (pronounced : spermathecae ), also called ''receptaculum seminis'' (: ''receptacula seminis''), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, Oligochaeta worms and certain other in ...

is missing, but a pseudospermatheca is present.R. T. Schuh, J. A. Slater: ''True Bugs of the World (Hemiptera: Heteroptera). Classification and Natural History.'' Cornell University Press, Ithaca, New York 1995, p.148.

Biology

The biology of Pachynomidae is poorly known. Museums contain only few samples of Pachynomidae, as they are often confused with Nabidae or

Reduviidae The Reduviidae is a large Cosmopolitan distribution, cosmopolitan family of the suborder Heteroptera of the Order (biology), order Hemiptera (true bugs). Among the Hemiptera and together with the Nabidae almost all species are terrestrial ambush ...

. It is possible that Pachynomidae are noctural ground-dwelling predators, as they are often collected from leaf litter or light traps. Immature forms are not known for most genera, with the exception of ''Aphelonotus''. Few species seem to show

sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

; it has been described in the genera ''Aphelonotus'' and ''Camarochilus''. Some species show wing dimorphism; it is known in ''Aphelonotus simplus'' males and ''Camarochilus americanus'' females, while the species ''Camarochiloides weiweii'' presents both brachypterous and macropterous morphs across sexes.

Taxonomy

The current genus ''Pachynomus'' was considered a subgenus of the genus '' Reduvius'' by its first describer Klug in 1830.

Carl Stål Carl Stål (21 March 1833 – 13 June 1878) was a Swedish people, Swedish entomologist specialising in Hemiptera. He was born at Karlberg Castle, Stockholm on 21 March 1833 and died at Frösundavik near Stockholm on 13 June 1878. He was the son ...

placed it and the genus '' Punctius'' in

, where they remained, confirmed by many subsequent authors (with the exception of Reuter 1908), until Carayon elevated the group to family rank in 1950. He considered the family to be most closely related to the assassin bugs (Reduviidae) due to the characteristics of the reproductive organs. Analysis of the mitochondrial genome recovered them as 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 ...

. The family includes the following subfamilies and genera: Subfamily Aphelonotinae :Genus ''Aphelonotus'' (tropical America, Central Africa) Subfamily Pachynominae :Genus ''Camarochilus'' (tropics of the New World) :Genus ''Camarochiloides'' (Old World) :Genus ''Pachynomus'' (Africa to India) :Genus ''Punctius'' (Africa to India)

References

Heteroptera families Cimicomorpha {{Heteroptera-stub