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Family Machilidae

Genus Petrobius

A genus of bristletail comprising two species, both of which are strongly, but not exclusively, linked with rocky coastal habitats in the British Isles.

The genus is fairly easily seperated from the other members of the Machilidae as its members have very distinctive ocelli, which are located underneath each compound eye, and are almost as wide as the compound eye itself. In addition the eyes are larger and rounder than those of the Dilta family, and the antennae (if intact) much longer.

The genus has the following species:-

Latin NameSynonymEnglish Name
Petrobius maritimus,Leach, 1809 petromachilis longicornis, reilly, 1915 Sea Bristletail
Petrobius brevistylus,Carpenter, 1913

Note that the synonymy of petromachilis longicornis is an interesting one, as Delaney 1954 shows a diagram with coxal lobes intermediate between the two petrobius species and states that males of the former can be seperated by having an extra pair of parameres on segment 8. I would be interested in any further information about the rise and fall of petromachilis longicornis as a species.