Decolopoda

Decolopoda is a genus of sea spider (class Pycnogonida) belonging to the family Colossendeidae. This genus includes two valid species, D. australis and D. qasimi. As the name of this genus implies, these two species are among the seven species of sea spider with five pairs of legs instead of the usual four leg pairs.

Discovery
The species D. australis is notable as the first polymerous (i.e., extra-legged) sea spider to be discovered and was first described by James Eights based on specimens found off the South Shetland Islands in the Antarctic region in 1834. Naturalists mostly ignored his discovery, dismissing the description by Eights as erroneous or based on a monstrosity, until the discovery of more ten-legged species several decades later. Authorities have since deemed one of these species, D. antarctica, which was described in 1905, to be a junior synonym of D. australis, but another species in this genus, D. qasimi, was described in 1993, based on a male holotype found off the coast of Queen Maud Land in Antarctica, and named for the Indian marine biologist Syed Zahoor Qasim.

Description
The sea spiders in this genus resemble those found in the genus Colossendeis (e.g., C. wilsoni) but are larger and retain chelifores in adults. Sea spiders of the giant species D. australis are bright scarlet, they often weigh more than 10 g, and their legs span more than 20 cm. The holotype for the species D. qasimi is dark maroon (when preserved) and has even longer legs (184.7 mm in length, compared to 100 mm for D. australis). The species D. qasimi also differs from other species by having denticulate spines on its ovigers and hair only on its legs. Phylogenetic studies indicate that the genus Decolopoda is nested within the genus Colossendeis in a phylogenetic tree, so that Colossendeis is paraphyletic with respect to Decolopoda.

Distribution
Both species in this genus are found in the Southern Ocean and are endemic to the Antarctic region.