Brandt, A.

Mühlenhardt-Siegel, U.

Rehm, Peter

Thatje, S.

English

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New records of the Southern Ocean species Cumella emergens(Cumacea: Nannastacidae) that emerged from the deep1 2 2 3Pete r Rehm , Ange l i ka B randt , U te Müh lenhardt -S iege l , and Sven Thatje  (1) Alfred Wegener Institute for Polar and Marine Research (AWI),Marine Animal Ecology,Columbusstrasse, D-27568 Bremerhaven,Germany, E-mail: prehm@awi-bremerhaven.de(2) Zoologisches Institut und Museum,Universität Hamburg, Martin-Luther-King Platz 3, 20146 Hamburg(3)  National Oceanography Centre, University of Southampton, European Way,Southampton, SO14 3ZH, UKA closer relationship of the fauna of the Antarctic and the Magellan an ancient Gondwana fauna or are related to the deep-sea fauna. region might be expected as the Scotia Arc islands could link both Little is known about the cumaceans of the deep sea around areas. Nevertheless, the species overlap of cumaceans from these Antarctica. Further deep-sea sampling is necessary to illuminate the areas is less than 10 percent . Therefore, the Antarctic was probably not origin of Antarctic cumaceans. However, the widespread occurrence only colonized from South America via the Scotia Arc, two other of Cumella emergens Cobera, 2000, in the Antarctic is an example of a scenarios were possible. Antarctic cumaceans possibly originate from biogeographic connection between Antarctic shallow-water IntroductionLivingstoneIsland0.5 mmRoss SeaCarapax of Cumella emergens,after Cobera (2000) 0.5 mmWeddell Sea0.5 mm 0.5 mmDifference in gender*-ratio between length and width < 1.3straight1-2 absent  present> 1.3angle1-4-anterior margin* Differences given in this table wereobserved between all populationsParaeopodsbearing exopods Attributend2  antenna CarapaxDistribution of C. emergensOnly male specimens of Cumella emergens were originally found off Livingstone Island (South Shetland Islands) in a depth of 649 m. During the thcruise ANTXXI-2 with the RV “Polarstern” and the 19  Antarctic expedition of RV “Italica” the species was also found in the Weddel Sea (157-405 m) and in the Ross Sea ( 316-410 m) in austral summer 2004. The species is closely related to the Atlantic deep-water species C. compacta, C. decipiens, and C. meridionalis from depth between 500 and 4566 m. Cumella emergensMorphological differences in populations5      / 6-7Pseudorostrum pointingratio between uropodal peduncle thand 5  abdominal segment12-3 6-7 absent flattenedforward upward upward normal  normal present  present1.2 1.2number of dorsal spines Attribute Livingstone Island Weddell Sea Ross Seadistal spine of carpusndof 2  paraeopodCarapaxConclusionAll discoveries of Cumella emergens were made with gear equipped with small mesh sizes (0.5 mm), which were only employed in recent years. The geographic range of the species covers the western part of the Antarctic. Using proper sampling gear it might be expected to find in eastern Antarctica as well.Some of the differences between Cumella emergens off Livingstone Island and the specimens from the Weddell Sea and the Ross Sea can possibly be ascribed to intraspecific variation. Differences between the animals from the Ross Sea and the Weddell Sea are less distinct. Nevertheless, these variations might be due to sibling species, because of the great distance between the two populations and the different ecological situations of the sample areas. A genetic analysis is p lanned to test  whether these specimens from the three populations of Cumella emergens belong to one, two, or even three different species.0.5 mm

New records of the Southern Ocean species Cumella emergens (Cumacea: Nannastacidae) that emerged from the deep

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