The classification of Antarctic appendicularians: t he Oikopleura gaussica group

CAPITANIO, F.; DAPONTE, M.C; ESNAL G. B.

ANTARCTIC SCIENCE

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2003 vol. 15 p. 476 - 482

0954-1020

The validity of the Antarctic species of the "Oikopleura gaussica group" (0. gaussica,0. valdiviae, 0 . drygalskii, and 0 . 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 justiSl their separation. The morphological variations found were ascribed either to intraspecific variability andíor 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 lefi 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.