Family COLOSSENDEIDAE Hoek, 1881

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Family COLOSSENDEIDAE Hoek, 1881

Introduction

This is the family of giant sea spiders: the genus Colossendeis contains spectacular giant forms (~70 cm in leg span), many of them from deep polar seas.

The family has been shown monophyletic (Arango & Wheeler 2007), although the position of Rhopalorhynchus and other genera attributed to it, is yet to be tested. The family is distributed worldwide, but is particularly diverse in Antarctic waters. Colossendeidae is one of the few families, together with Nymphonidae and Pycnogonidae, in which there is occurrence of polymeric species, i.e. species with one or two extra body segments (5- or 6-, then 10- or 12-legged species). They are classified in the genera Decolopoda, Dodecolopoda and Pentacolossendeis.

The embryology of colossendeids is unknown. Eggs, larvae and protonymphons have never been found. While Colossendeis and the polymeric forms are mostly restricted to deep, cold waters, Hedgpethia and Rhopalorhynchus can be found in shallow, tropical waters. A new species in each of these genera has been described recently in Australia, namely Hedgepthia calva Arango 2009, and Rhopalorhynchus magdalena Staples, 2009).

Diagnosis

Size usually very large, without tubercles; proboscis usually long, cylindrical, carried horizontally; chelifores lacking in adults; palps long, 9- or 10-segmented; ovigers very long, in both sexes, 10-segmented, with strong functional strigilis having several rows of spines and terminal claw; legs usually very long, slender, no species with auxiliary claws. Male cement gland(s) openings unknown, eggs and larval development unknown. Contains 10- and 12-legged forms.