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'Psocoptera' are an order of insects that are commonly known as booklice or barklice. They first appeared in the Permian era, 295–248 million years ago. They are often regarded as the most primitive of the hemipteroids ^[1]. Their name originates from the Greek word ''psokos'' meaning or and ''ptera'' meaning wings ^[2]. There are more than 5,500 species in 41 families in three suborders. Many of these species have been described in recent years ^[3].
They range in size from 1–10 mm in length.
They receive their common name because members of this order are commonly found amongst old books — they feed upon the paste used in binding. No member of this order is currently endangered.

Contents

Classification

Suborder Trogiomorpha

Suborder Troctomorpha

Suborder Psocomorpha

References

Classification

The Order Psocoptera is divided into three suborders.

Suborder Trogiomorpha

'Trogiomorpha' is the smallest suborder of the Psocoptera ''sensu stricto'' (i.e. excluding Phthiraptera), with about 340 species in 7 families, ranging from the monospecific fossil family Archaeotropidae to the speciose Lepidopsocidae (over 200 species). Trogiomorpha have antennae with many segments (more than 20). They always have three-segmented tarsi ^[4].
Trogiomorpha comprises Infraorder 'Atropetae' (families Archaeotropidae, Empheriidae, Lepidopsocidae and Psoquillidae) and Infraorder 'Psocathropetae' (families Psyllipsocidae and Prionoglarididae).

Suborder Troctomorpha

'Troctomorpha' have antennae with 15 segments and two-segmented tarsi. Troctomorpha are now known to also contain the order Phthiraptera (lice). Troctomorpha like ''Liposcelis'' (which are similar to lice in morphology) are often found in birds' nests, and it is possible that a similar behaviour in the ancestors of lice is at the origin of the parasitism seen today .
Troctomorpha comprises the Infraorder 'Amphientometae' (families Amphientomidae, Compsocidae, Electrentomidae, Musapsocidae, Protroctopsocidae and Troctopsocidae) and Infraorder 'Nanopsocetae' (families Liposcelididae, Pachytroctidae and Sphaeropsocidae).

Suborder Psocomorpha

'Psocomorpha' is the largest suborder of the Psocoptera ''sensu stricto'' (i.e. excluding Phthiraptera), with about 3,600 species in 24 families, ranging from the species-poor Bryopsocidae (2 spp.) to the speciose Psocidae (about 900 spp) .
Psocomorpha are notable for having antennae with 13 segments. They have two- or three-segmented tarsi, this condition being constant (e.g. Psocidae) or variable (e.g. Pseudocaeciliidae) within families. Their wing venation is variable, the most common type being that found in the genus ''Caecilius'' (rounded, free areola postica, thickened, free pterostigma, r+s two-branched, m three-branched). Additional veins are found in some families and genera (''Dicropsocus'' and ''Goja'' in Epipsocidae, many Calopsocidae, etc.)
Psocomorpha comprises Infraorder 'Epipsocetae' (families Cladiopsocidae, Dolabellopsocidae, Epipsocidae, Neurostigmatidae and Ptiloneuridae), Infraorder 'Caeciliusetae' (families Amphipsocidae, Asiopsocidae, Caeciliusidae, Dasydemellidae and Stenopsocidae), Infraorder 'Homilopsocidea' (families Archipsocidae, Bryopsocidae, Calopsocidae, Ectopsocidae, Elipsocidae, Lachesillidae, Mesopsocidae, Peripsocidae, Philotarsidae, Pseudocaeciliidae and Trichopsocidae) and Infraorder 'Psocetae' (families Myopsocidae, Psilopsocidae and Psocidae).

References

1. Firefly Encyclopedia of Insects and Spiders, Christopher O'Toole, , , , 2002, ISBN 1-55297-612-2
2. Psocoptera John R. Meyer
3. New genera of Psocoptera (Insecta), from Mexico, Belize and Ecuador (Psoquillidae, Ptiloneuridae, Lachesillidae), Alfonso N. García Aldrete, , , Zootaxa, 2006
4. Psocoptera (Insecta): World Catalogue and Bibliography, C. Lienhard & C. N. Smithers, , , Instrumenta Biodiversitatis, 2002