The genetics and taxonomy of Southern Ocean Octopidae, with special reference of the genus Pareledone

• Main Author: Allcock, Anne Louise
• Format: Thesis
• Language: English
• Published: 1997
• Subjects: Antarctic; Antarctic Peninsula; Southern Ocean; The Antarctic; The Beak; Weddell; Weddell Sea; Antarc*
• Online Access: https://oceanrep.geomar.de/id/eprint/50789/; https://oceanrep.geomar.de/id/eprint/50789/1/Allcock_1997.pdf

The Octopodidae of the Southern Ocean have been afforded little attention since the early part of this century and their taxonomy is poorly known. During this study, three extensive trawling programmes took place off South Georgia, off the Antarctic Peninsula and in the Weddell Sea. A further collecting programme was arranged in the Falkland Islands, just north of the Antarctic Polar Front. Twenty-six putative species were recorded from the Southern Ocean; there are -just sixteen previously described species from this region. Allozyme electrophoresis was used to validate the specific status of samples. A dendrogram was constructed from genetic identity values. Ten species of Pareledone clustered together suggesting that the genus is valid. It has been noted that members of this genus have only plesiomorphic and no apomorphic characters in common, hence there was previously no evidence that Pareledone species share a unique evolutionary history. Three species of Pareledone clustered separately, but it has already been suggested that these species should be removed from the genus on clear morphological grounds. The dendrogram provided evidence that supported the use of sucker serialisation as a dichotomous character to subdivide the family Octopodidae, but refuted the use of the presence I absence of an ink sac as a subfamilial character. The use of morphological measurements in octopodid taxonomy was tested using multivariate statistical techniques. When a large suite of characters was measured there was satisfactory discrimination between species. Counts of sucker numbers and gill lamellae were particularly useful for discrimination at the specific level, but phenograms constructed from analyses of these and other measurements appeared to be of little phylogenetic use. The shape and size of the beak were found to be more useful at the generic level. A phenogram constructed from analyses of beak morphology bore some resemblance to a dendrogram constructed from genetic identity values. Analysis of more genera is ...