New bobtail squid (Sepiolidae: Sepiolinae) from the Ryukyu islands revealed by molecular and morphological analysis

Abstract

Bobtail squid are emerging models for host–microbe interactions, behavior, and development, yet their species diversity and distribution remain poorly characterized. Here, we combine mitochondrial and transcriptome sequences with morphological analysis to describe three species of bobtail squid (Sepiolidae: Sepiolinae) from the Ryukyu archipelago, and compare them with related taxa. One Ryukyuan type was previously unknown, and is described here as Euprymna brenneri sp. nov. Another Ryukyuan type is morphologically indistinguishable from Sepiola parva Sasaki, 1913. Molecular analyses, however, place this taxon within the genus Euprymna Steenstrup, 1887, and additional morphological investigation led to formal rediagnosis of Euprymna and reassignment of this species as Euprymna parva comb. nov. While no adults from the third Ryukyuan type were found, sequences from hatchlings suggest a close relationship with E. pardalota Reid, 2011, known from Australia and East Timor. The broadly sampled transcriptomes reported here provide a foundation for future phylogenetic and comparative studies.

Morphological and Molecular Assessments of Bobtail Squids (Cephalopoda: Sepiolidae) Reveal a Hidden History of Biodiversity

“…All the studied individuals were successfully linked with their taxonomic name and no inconsistencies arose among the newly sequenced material. Nevertheless, wrong identifications of bobtail squids are relatively frequent in GenBank, as previously reported by Groenenberg et al (2009) and Sanchez et al (2019). The work of Groenenberg et al (2009) on DNA barcoding on vouchered individuals has solved some of the previously misidentified sequences.…”

“…leucoptera. That is the case of beak and radulae morphologies, which are rarely used in bobtail squid taxonomy (e.g., Kubodera and Okutani, 2011;Sanchez et al, 2019), and spermatophores. The use of spermatophores in cephalopod taxonomy should be taken with caution, as our study also shows.…”

“…It is also remarkably that Olmos-Pérez et al (2018b) found a species ("Heteroteuthinidae" sp.) in European waters whose sequences cannot be assigned to any sequenced species of bobtail squid, while Sanchez et al (2019) discovered two new species of the genus Euprymna in Pacific waters. All these recent new species discoveries stress the need of new taxonomic studies in both benthic and pelagic bobtail squids on a worldwide basis.…”

“…The sequences AY293710 and AY293715 were described as Lusepiola birostrata (Sasaki, 1918) or Euprymna morsei (Verrill, 1881) and their divergence is compatible with an intraspecific distance. Sanchez et al (2019) assigned those sequences to Sepiola (= Lusepiola) birostrata. Euprymna hyllebergi, E. scolopes, and E. tasmanica showed 2-4 highly divergent clades.…”

“…The family Sepiolidae Leach, 1817, commonly known as bobtail squids, is a very diverse group of benthic and nektonic small to medium size cephalopods. In recent years, the taxonomy and systematics of the family has been dynamic, including a few molecular phylogenetic studies (e.g., Groenenberg et al, 2009;Sanchez et al, 2019), major systematics reviews (Bello, 2019(Bello, , 2020 and the description of a relatively large number of new species (e.g., de Heij and Goud, 2010; Kubodera and Okutani, 2011;Sanchez et al, 2019). In the last decade, new species have been even discovered in the Mediterranean Sea (Bello, 2013;Bello and Salman, 2015), where bobtail squid diversity has been extensively studied for more than a century (Bello, 2015(Bello, , 2019.…”