Family CADDIDAE Banks, 1892

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Introduction

The Caddidae are a small but distinct group of Palpatores with a peculiar bipolar distribution. The Caddinae are restricted to a single genus, Caddo Banks, with two Recent species found in North America and Japan, and an Oligocene species from Baltic Amber. The Acropsopilioninae consist of four genera and are generally found in the southern continents. However, some species occur in Mexico and North America (Shear 1975). The four acropsopilionine genera have varying distributions with Caddella Hirst restricted to South Africa, Hesperopilio Shear found in south-western Australia, Acropsopilio Silvestri in eastern Australia, New Zealand, southern South America, Mexico, U.S.A. and Canada, and Austropsopilio Forster from eastern Australia and Chile.

The Caddidae are the only members of the superfamily Caddoidea, which have been shown by Shultz (1998) to represent the sister-group to the Phalangioidea.

Diagnosis

Caddids can be recognised by the enormous eye tubercle that covers nearly all of the carapace. Other important features include the lack of accessory spiracles on the pedal tibiae, and the comparatively large abdominal spiracles which are bridged over with granules.

General References

Shear, W.A. 1975. The opilionid family Caddidae in North America, with notes on species from other regions (Opiliones, Palpatores, Caddoidea). Journal of Arachnology 2: 65-88

Shultz, J.W. 1998. Phylogeny of Opiliones (Arachnida): an assessment of the "Cyphopalpatores" concept. Journal of Arachnology 26: 257-272

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