AY Honors/Insect/Psocoptera

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Psocoptera are an order of insects that are commonly known as booklice, barklice or barkflies[1]. They first appeared in the Permian era, 295–248 million years ago. They are often regarded as the most primitive of the hemipteroids ^&. Their name originates from the Greek word psokos meaning gnawed or rubbed and ptera meaning wings ^&. There are more than 5,500 species in 41 families in three suborders. Many of these species have only been described in recent years ^&.

They range in size from 1–10 mm in length.

The species known as booklice received their common name because they are commonly found amongst old books — they feed upon the paste used in binding. The barklice are found harmlessly on trees, feeding on algae and lichen. No member of this order is currently endangered; in fact, in 2007, Atlantopsocus adustus, a species native to Madeira and the Canary Islands, was found to have colonised the mild Cornish coast of southwest England.^&

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 ^&.

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), and are therefore paraphyletic, as are Psocoptera as a whole. Some 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 Hemipsocidae, Myopsocidae, Psilopsocidae and Psocidae).