Decolopoda | |
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Illustration of D. australis, from a specimen found at the South Shetlands by the Scottia Expedition. | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Class: | Pycnogonida |
Order: | Pantopoda |
Family: | Colossendeidae |
Genus: | Decolopoda Eights, 1835 |
Species | |
Decolopoda is a genus of sea spider (class Pycnogonida) belonging to the family Colossendeidae. [1] This genus includes two valid species, D. australis and D. qasimi . [1] 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. [2] The species D. australis is notable as the first polymerous (i.e., extra-legged) sea spider to be discovered. [3] [4]
The species D. australis was first described by the American naturalist James Eights based on specimens found in sea along the South Shetland Islands in the Antarctic region in 1834. [5] [3] [4] 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. [3] [4] The French zoologist Eugène-Louis Bouvier described one of these sea spiders as a new species, D. antarctica, in 1905, but authorities have since deemed D. antarctica to be a junior synonym of D. australis, [1]
Another species in this genus, D. qasimi, was described by V. Jaya Sree, R.A. Sreepada, and A.H. Parulekar of the National Institute of Oceanography in India in 1993. The original description of this species is based on a male holotype found off the coast of Queen Maud Land in Antarctica. This species is named for the Indian marine biologist Syed Zahoor Qasim. [3]
Sea spiders of the giant species D. australis have five pairs of legs and are bright scarlet. [5] These sea spiders often weigh more than 10 g, and their legs span more than 20 cm. [6] The holotype for the species D. qasimi also has ten legs, is dark maroon (when preserved), and has even longer legs (184.7 mm in length, compared to 100 mm for D. australis). [3] The species D. qasimi also differs from D. australis by having denticulate spines on its ovigers and hair only on its legs. [3]
The ten-legged sea spiders in the genus Decolopoda resemble the twelve-legged sea spiders in the genus Dodecolopoda . For example, both genera feature long legs, a long proboscis that curves downward and is distally inflated, and a tarsus that is much longer than the propodus. [7] The species in Decolopoda, however, are smaller, feature a shorter tarsus and longer claw compared to the propodus, and have fewer legs than Dodecolopoda. [8]
The sea spiders in the genus Decolopoda also resemble those found in the genus Colossendeis (e.g., C. wilsoni) but are larger and retain chelifores in adults. [4] [3] Phylogenetic studies based on molecular data indicate that the genus Decolopoda is nested within the genus Colossendeis in a phylogenetic tree. Thus, Colossendeis is paraphyletic with respect to Decolopoda. [9] This paraphyly would normally make Colossendeis a junior synonym of Decolopoda, the older name, and require these genera to merge under the name Decolopoda. To avoid this disruption, authorities keep these genera under different names and retain Colossendeis as a paraphyletic genus. [10]
Both species in this genus are found in the Southern Ocean and are endemic to the Antarctic region. [11]
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Sea spiders are marine arthropods of the order Pantopoda, belonging to the class Pycnogonida, hence they are also called pycnogonids. They are cosmopolitan, found in oceans around the world. The over 1,300 known species have leg spans ranging from 1 mm (0.04 in) to over 70 cm (2.3 ft). Most are toward the smaller end of this range in relatively shallow depths; however, they can grow to be quite large in Antarctic and deep waters.
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Lyssomaninae is a subfamily of jumping spiders. It includes four genera, three from the New World.
Nymphon is a genus of sea spiders in the family Nymphonidae. The species of sea spiders within the genus Nymphon are all benthic organisms and are found in abyssal and bathyal areas of the ocean. This is a fully marine group and can be found at various depths ranging from the littoral zones to the deep sea. They are found in most major oceans across the globe with a strong distribution around polar regions: Arctic and Antarctic waters. Out of the sea spider genus, Nymphon is the most rich, with a majority of the species within the genis being found in the Southern Ocean region. This genus may also contain bioluminescent species.
Pycnogonidae is a family of sea spiders.
Pycnogonum is a genus of sea spiders in the family Pycnogonidae. It is the type genus of the family.
Nymphon gracile is a species of sea spider first described by William Elford Leach in 1863. The species highly resembles other members of the genus Nymphon, and species identification from morphological traits alone is, therefore, a complex task.
Colossendeis is a genus of sea spider belonging to the family Colossendeidae. Phylogenetic analysis based on molecular data indicates that this genus is paraphyletic with respect to the genera Decolopoda and Dodecolopoda, which are found to be nested within the genus Colossendeis in a phylogenetic tree.
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Palaeoisopus is a monotypic genus of fossil pycnogonid, known only by one species, Palaeoisopus problematicus, discovered from the Lower Devonian Hunsrück Slate of Germany. It have several characters unusual for a pycnogonid, such as swimming legs with alternating size, medially-arranged eyes, and most significantly, a long, segmented abdomen, which were highly reduced in modern counterparts.
Colossendeis colossea is a species of sea spider in the family Colossendeidae. The species was first described by Edmund B. Wilson in 1881. It is the largest pycnogonid species known to science, reaching a leg span of 70 cm (28 in). Body length, including proboscis and abdomen, can reach 7 cm (2.8 in).
Colossendeis proboscidea is a species of sea spider in the family Colossendeidae. It is native to the Arctic and northeast Atlantic.
Dodecolopoda is a monotypic genus of sea spider in the family Colossendeidae. The only species in this genus is Dodecolopoda mawsoni. This species is notable as one of only two species of sea spider with six pairs of legs and the first such species to be discovered.
Cambropycnogon klausmuelleri is a presumed pycnogonid larva from the Upper Cambrian Orsten, having been referred to before description as "Larva D".