Population genetic structure and phylogenetic relationships reveal cryptic biodiversity in the Uroteuthis (Photololigo) duvaucelii (Cephalopoda: Loliginidae) species complex

Uroteuthis (Photololigo) duvaucelii is an economically important fishery species in the western Pacific Ocean. However, there is a scarcity of research concerning the population structure and genetic diversity of this species. Therefore, a genetic diversity analysis of 269 samples of U. (P.) duvaucelii that were collected from 10 geographic populations in the western Pacific Ocean and combined with sequences from GenBank, was implemented utilizing mitochondrial cox1 and rrnL gene markers. A total of 57 haplotypes with 106 variable sites were detected in cox1 sequences, while 49 haplotypes with 70 variable sites were obtained in rrnL sequences. Phylogenetic trees and a haplotype network both indicated that U. (P.) duvaucelii had fewer genetic distinctions among Chinese populations, but there were large genetic distinctions compared to the other populations. The AMOVA analysis supported that genetic variation was centered on four clades. Species delimitation classified U. (P.) duvaucelii sequences into four MOTUs and integrated them with genetic distance and genetic differentiation indices, demonstrating that these samples had achieved the level of species divergence. The genetic variations may be caused by geographic barriers among populations as well as differences in sea temperature. This study supplies biogenetic references for future research on species differentiation in cephalopods and the rational employment of germplasm resources of U. (P.) duvaucelii.