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

Gustavo Sanchez,Ferdinand Marlétaz,Oleg Simakov,Amanda Reid,Chikatoshi Sugimoto,Jeffrey Jolly,Chika Azama,Daniel S Rokhsar

doi:10.1038/s42003-019-0661-6

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.

Highlights

Bobtail squid are emerging models for host–microbe interactions, behavior, and development, yet their species diversity and distribution remain poorly characterized
To examine relationships among the Ryukyuan types and other species, we used maximum likelihood to estimate a phylogenetic tree with haplotypes from cytochrome oxidase I (COI) sequences (Fig. 2), combining publicly deposited data (Supplementary Table 1) with additional sequences from our Ryukyuan samples and new sequences from 9 previously described bobtail and related squid species (Materials and methods; Supplementary Table 2)
We found that Ryukyuan Type 1 formed a clade with, and is clearly related to, E. pardalota, a species described from northern Australia[39]

Summary

Introduction

Bobtail squid are emerging models for host–microbe interactions, behavior, and development, yet their species diversity and distribution remain poorly characterized. 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. Together with Idiosepiidae they are the sister group of the true squids (Teuthoidea)[1] Due to their small size and ease of culturing in captivity, species of Euprymna and Sepiola are increasingly emerging as model systems for a range of biological studies[2,3,4]. Transcriptome sequences complement DNA barcoding and morphological analysis by providing sequence data from multiple unlinked nuclear coding regions Information from these loci enables more accurate species identification and the reconstruction of their phylogenetic relationships

Objectives

Methods

Results

Conclusion