Identification, distribution and relative abundance of paralarval gonatid squids (Cephalopoda: Oegopsida: Gonatidae) from the Gulf of Alaska, 2001–2003

Paralarvae of the family Gonatidae were sampled in the Gulf of Alaska during spring 2001–2003. Taxonomic characters were determined to allow identification of the specimens to species. The dorsal head chromatophore pattern (DHCP) was the most robust character and allowed identification to species for the first time without requiring the removal and examination of the radula. Six different DHCPs were found among the six species in the study area. The 1140 specimens collected consisted of the following six species: Berryteuthis anonychus (759), Berryteuthis magister (71), Gonatopsis borealis (155), Gonatus kamtschaticus (1), Gonatus madokai (4) and Gonatus onyx (143). The specimens had a size range of 3.0–20.63 mm dorsal mantle length with the majority of specimens smaller than 10 mm. All species showed an increasing trend in abundance from the shelf (0–200 m) to the slope (200–1000 m) to the basin (>1000 m) except G. onyx in 2001 and 2002. Wide variation in distribution and abundance was found for the four most abundant species; however, in general, B. anonychus was most abundant and widely distributed, followed by Gonatopis borealis, Gonatus onyx and B. magister

Description and phylogenetic relationships of a new genus of octopus, Sasakiopus (Cephalopoda: Octopodidae), from the Bering Sea, with a redescription of Sasakiopus salebrosus (Sasaki, 1920)

A new genus of octopus, Sasakiopus, is erected for the species S. salebrosus (Sasaki, 1920) n. comb. Sasakiopus salebrosus is redescribed from the holotype and from new material recently collected in the eastern Bering Sea. Molecular phylogenetic analysis of one nuclear and three mitochondrial genes revealed that the new genus is the sister taxon of a clade containing the genera Benthoctopus and Vulcanoctopus. The clade containing Sasakiopus, Benthoctopus and Vulcanoctopus is the sister group of Enteroctopus. The genus Bathypolypus falls outside this clade. Sasakiopus differs from Bathypolypus and Enteroctopus by the shape of its ligula (simple in Sasakiopus and Benthoctopus, laminate in Bathypolypus and elongate in Enteroctopus), from Enteroctopus by the absence of enlarged suckers in mature male animals and from Benthoctopus by its skin sculpture and ability to ink

Trophic ecology of the deep-sea cephalopod assemblage near Bear Seamount in the Northwest Atlantic Ocean

Cephalopods compose a vital component of marine food webs worldwide, yet their trophic roles remain largely unresolved. This study used stable carbon and nitrogen isotopes to describe the trophic structure, ontogeny, and isotopic niche overlap of cephalopod groups from pelagic and near-bottom habitats around Bear Seamount in the Northwest Atlantic Ocean. Beaks from 225 specimens (13 families; 27 species), primarily from juvenile and sub-adult life stages, were collected during a deep-sea biodiversity cruise conducted in 2012. Differences in mean δ15N and δ13C values were detected among some families and across species within the fam - ilies Ommastrephidae, Histioteuthidae, Mastigoteuthidae, and the superfamily Argonautoidea. Trophic positions ranged from 2.7 to 4.5 across assemblage members, with top positions held by Illex illecebrosus, Histioteuthis reversa, Octopoteuthis sicula, Taonius pavo, and Haliphron atlanticus. Cephalopod families exhibiting the broadest and most diverse isotopic niche widths overall included Ommastrephidae, Cranchiidae, and Octopoteuthidae. Families with the narrowest isotopic niches included Onychoteuthidae and the monospecific Joubiniteuthidae, and Vampyroteuthidae. Trophic position increased significantly with body size (mantle length) across all individuals sampled, and ontogenetic shifts in δ15N values were detected in 7 species. The continuous gradient and broad range of isotope values across families, species, and body sizes suggest an unstructured assemblage comprised of generalist and specialist foragers distributed throughout a vertical depth range of pelagic (depleted δ13C values) to near-bottom bathy/benthopelagic (enriched δ13C values) habitats. The results provide some of the first quantitative trophic metrics for many poorly studied species and advance our understanding of the diversity of cephalopod ecological roles in marine ecosystems