Morphological variability of the rare bush-club squid <I>Batoteuthis </I>(Cephalopoda, Batoteuthidae)?

Abstract

A specimen of Batoteuthidae was caught during the research cruise ATLANTIS 2009 on 21 March 2009 at 45°09.51&#39; S - 45°08.07&#39; S - 59°29.04&#39; W - 59°27.98&#39;W (Patagonian slope), depth 1195-1221 m. This specimen is a juvenile male, 105 mm mantle length. It is the largest Batoteuthis with complete tentacles captured to date. It shares the main diagnostic characters of the family. We compared that specimen with the types of Batoteuthis skolops, the only known species in the family. Our specimen has several differences from the types (lower tail length index, different fin shape, arm length indices 3-4 times longer, tentacles and clubs 4 or 5 times longer than the types, distinct arrangement of suckers in ventral arms, and different number, size and disposition of suckers in tentacular clubs) suggesting that it might be a different species. However, we cannot refute the alternative hypothesis that the differences are ontogenic. Until additional good specimens become available or molecular analyses are undertaken, we recommend a conservative approach of considering our specimen tentatively to be a growth form of Batoteuthis skolops.