CEPHALOPOD BIOLOGY AND EVOLUTION The ink sac clouds octopod evolutionary history Jan M. Strugnell • Mark D. Norman • Michael Vecchione • Michelle Guzik • A. Louise Allcock Received: 13 December 2012 / Accepted: 4 April 2013 Ó Springer Science+Business Media Dordrecht 2013 Abstract Difficulties in elucidating the evolutionary history of the octopods have arisen from problems in identifying informative morphological characters. Recent classifications have divided the largest group, the incirrate octopods, into five groups. These include the pelagic superfamily Argonautoidea and three gelatinous pelagic families (Vitreledonellidae, Bolita- enidae, Amphitretidae). All benthic incirrate octopods have been accommodated in the family Octopodidae, itself divided into four subfamilies, Octopodinae, Eledoninae, Bathypolypodinae and Graneledoninae, which are defined by the presence or absence of an ink sac, and uniserial or biserial sucker arrangements on the arms. We used relaxed clock models in a Bayesian framework and maximum likelihood methods to analyse three nuclear and four mitochondrial genes of representatives from each of the previous subfam- ilies. Strong evidence indicates that the family Octo- podidae is paraphyletic and contains the gelatinous pelagic families. The subfamilies of Octopodidae recognised in earlier works do not reflect evolutionary history. The following clades were supported in all analyses: (1) Eledone/Aphrodoctopus, (2) Callistocto- pus/Grimpella/Macroctopus/Scaeurgus, (3) Abdopus/ Ameloctopus/Amphioctopus/Cistopus/Hapalochlaena/ Octopus, (4) Enteroctopus/Muusoctopus/Vulcanocto- pus, (5) Vitreledonella/Japetella, (6) Southern Ocean endemic and deep-sea taxa with uniserial suckers. Electronic supplementary material The online version of this article (doi:10.1007/s10750-013-1517-6) contains supplementary material, which is available to authorized users. Guest editors: Erica A. G. Vidal, Mike Vecchione & Sigurd von Boletzky / Cephalopod Life History, Ecology and Evolution J. M. Strugnell (&) Department of Genetics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC 3086, Australia e-mail: J.Strugnell@latrobe.edu.au M. D. Norman Sciences, Museum Victoria, GPO Box 666, Melbourne, VIC 3001, Australia M. Vecchione NMFS National Systematics Laboratory, National Museum of Natural History, MRC-153, Smithsonian Institution, P.O. Box 37012, Washington, DC 20013-7012, USA M. Guzik Australian Centre for Evolutionary Biology and Biodiversity, School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA, Australia A. L. Allcock Zoology, School of Natural Sciences and Ryan Institute, National University of Ireland, Galway, University Road, Galway, Ireland 123 Hydrobiologia DOI 10.1007/s10750-013-1517-6