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The classification of Antarctic appendicularians: the Oikopleura gaussica group

Published online by Cambridge University Press:  02 December 2003

F.L. CAPITANIO ,
M.C. DAPONTE  and
G.B. ESNAL
F.L. CAPITANIO
Affiliation:
Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina, CONICET
M.C. DAPONTE
Affiliation:
Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina, CONICET
G.B. ESNAL
Affiliation:
Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EHA Buenos Aires, Argentina, CONICET
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Abstract

The validity of the Antarctic species of the “Oikopleura gaussica group” (O. gaussica, O. valdiviae, O. drygalskii, and O. weddelli) is discussed. The characteristics of new material from South Georgia and the Bellingshausen Sea are compared with the original descriptions. We examined 495 specimens at different stages of maturity and concluded that the characters used to differentiate these species of Oikopleura have not enough weight to justify their separation. The morphological variations found were ascribed either to intraspecific variability and/or to the different degree of maturity of the specimens examined of a single species, Oikopleura gaussica. The main taxonomic characters for the identification of this species are: the particular way in which the flat triangular gonads surround the intestinal ball like a sheath, the equal size of the two lobes of the stomach, the oesophagus entering the postero-dorsal edge of the rounded left lobe of the stomach, the presence of oval and some times lobate oral glands, and the variable number of subchordal cells (4 to 14) arranged in a single row on the right (ventral) side of the chorda.

Keywords

intraspecific variabilitySouthern OceanTunicata
Type
Research Article
Information
Antarctic Science , Volume 15 , Issue 4 , December 2003 , pp. 476 - 482
Copyright
© Antarctic Science Ltd 2003

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