Morphological assessment of the Octopus vulgaris species complex evaluated in light of molecular‐based phylogenetic inferences

Abstract

Cryptic species are common in the ocean, particularly among marine invertebrates such as octopuses. Delineating cryptic species is particularly problematic in octopus taxonomy where the plasticity recorded among taxonomic characters often results in low resolution at the species level. This study investigated the morphological relationships among seven phylogenetic clades (identified using cytochrome c oxidase subunit I) of the broadly distributed Octopus vulgaris species complex and close relatives. Morphological analyses in this study were successful in delimiting O. sinensis, Brazilian O. vulgaris and O. vulgaris sensu stricto, which was congruent with the molecular findings of this study. Analyses based on male morphology were successful in distinguishing 14 of 15 total pairwise comparisons and proved to be a more reliable indicator of species‐level relationships in comparison with female morphology. The majority of characters with the greatest discriminatory power were male sexual traits. Significant morphological differences were also recorded among sampling localities of conspecifics, with phenotype showing correlation with local environmental data. The findings of this study support the hypothesis that multiple O. vulgaris‐like species are currently being incorrectly treated under a single species name, O. vulgaris. Octopuses being exported globally under the name O. vulgaris are of extremely high fisheries market value and profile. Our findings have potentially significant implications for the naming and conservation of commercially harvested members of this species complex throughout their ranges.

Genome-wide sequencing uncovers cryptic diversity and mito-nuclear discordance in theOctopus vulgarisspecies complex

“…1). A recent morphology-based investigation of this species complex (and close relatives) supported mtDNA-derived phylogenetic structure 32 . However, no studies of this group have attempted to validate these findings using nuclear data.…”

“…Based on indistinguishable morphology, O. vulgaris was historically considered to have a cosmopolitan distribution, occurring in the Mediterranean Sea and the shallow tropical waters surrounding Australasia, Europe, Africa, Asia and the Americas 23 . However, recent mtDNA-based studies have provided some evidence for the existence of species boundaries among populations of O. vulgaris [24][25][26][27][28][29][30][31][32] . Such mtDNA evidence suggests O. vulgaris comprises a complex of morphologically similar but genetically distinct O. vulgaris-like species (the 'Octopus vulgaris species complex'), which is composed of several hypothesised species 'Types' 33 ( Fig.…”

Effects of co-supply ratios of swimming crab Portunus trituberculatus zoeae and Artemia on survival and growth of East Asian common octopus Octopus sinensis paralarvae under an upwelling culture system

“…The East Asian common octopus, Octopus sinensis , is distributed in shallow temperate waters in the western North Pacific oceans (Amor et al, ; Gleadall, ). In the field of aquaculture research, common octopuses that include Atlantic and Mediterranean species Octopus vulgaris and western North Pacific species O .…”

Phylogenetics and comparative analysis of the mitochondrial genomes of three violet‐ringed octopuses

“…At present, the classification and phylogenetics of this family are mainly based on morphology, molecular studies using a combination of partial mitochondrial and nuclear gene regions, or whole mitochondrial genomes (Allcock, Cooke, & Strugnell, 2011;Allcock, Lindgren, & Strugnell, 2015;Lindgren, Pankey, Hochberg, & Oakley, 2012;Strugnell & Nishiguchi, 2007;Strugnell, Norman, Jackson, Drummond, & Cooper, 2005;Uribe & Zardoya, 2017). Due to a lack of diagnostic morphological characters, elucidation of the species-level taxonomy of octopuses has been hindered (Amor et al, 2017). This phenomenon is very common in Cephalopoda, and examples of successful species delineation are rare (Amor et al, 2017;Bolstad et al, 2018;Braid, Mcbride, & Bolstad, 2014).…”

“…Due to a lack of diagnostic morphological characters, elucidation of the species-level taxonomy of octopuses has been hindered (Amor et al, 2017). This phenomenon is very common in Cephalopoda, and examples of successful species delineation are rare (Amor et al, 2017;Bolstad et al, 2018;Braid, Mcbride, & Bolstad, 2014).…”