Monday, 28 October 2013

Two new species of Siphonophore from Monterey Bay, California.

Siphonophores are colonial Hydrozoans (Cnidarians related to Corals and Jellyfish) which live as members of the marine plankton (organisms that drift in ocean currents). Some species superficially resemble Jellyfish, but their internal structure is quite different, with each Jelly being a colony of hundreds or thousands of connected individuals called zooids. These zooids are not typically identical, with specialist feeding and reproductive zooids typically being separate, and some species having other specialist forms. Some species grow extremely large, with the largest, Praya dubia often reaching over 50 m in length; though this is a deepwater form living 700-1000 m bellow the surface, and is seldom seen. More familiar is the Portuguese Man o' War (Physalia physalis) which reaches a little under 50 m in length, but which stays on the surface due to modified zooids which act as floats.

In a paper published in the journal Zootaxa on 27 August 2013, Stefan Siebert of the Department of Ecology and Evolutionary Biology at Brown University, Phil Pugh of the National Oceanography Centre in Southampton, England, Steven Haddock of the Monterey Bay Aquarium Research Institute and Casey Dunn, also of the Department of Ecology and Evolutionary Biology at Brown University describe two new species of Siphonophore from Monterey Bay, California. Both are placed in the genus Apolemia.

The first new species in named Apolemia lanosa, from the Latin 'lana', meaning 'wooly'. Apolemia lanosa is an approximately 2 m colourless Siphonophore with a single siphosome (stem) along which individual zooids are arranged trailing behind a small nectophore (float made from modified zooids). The zooids are densely packed on the siphosome, giving the colony a wooly appearance. Apolemia lanosa was found at depths of between 636 and 1506 m in Monterey Bay, it has also been sighted at Davidson Seamount (130 km southwest of Monterey Bay at depths of between 439 and 1159 m, and may be found of the coast of Japan.

Apolemia lanosa colony, nectophore is bottom right. Siebert et al. (2013).

Apolemia lanosa, nectophore and part of siphonophore with accompanying zooids. Scale bar is 2 mm. Siebert et al. (2013).

The second new species is named Apolemia rubriversa, meaning 'red furrow'; it has red pigmentation in a furrow on its nectophore. Apolemia rubriversa has larger zooids than Apolemia lanosa, resembling short tentacles rather than wooly hair. It has a distinct brownish tinge. Apolemia rubriversa was found at depths between 374 and 901 m in Monterey Bay, the species was also found in the Gulf of California (Mexico) and may be present off Vancouver and near the Bahamas.

Apolemia rubriversa colony, nectophore is bottom center. Siebert et al. (2013).

Apolemia rubriversa, nectophore and part of siphonophore with accompanying zooids. Scale bar is 2.5 mm. Siebert et al. (2013).

See also Five new species of deepwater Corals from the South American continental shelfJellyfish force closure of Swedish nuclear power plantPunctatus emeiensis, not a Cnidarian after all? A new species of Hydrozoans from British Columbia and The mysterious ebb and flow of Jellyfish populations.

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