A New Subspecies of the Schoolmaster Gonate Squid, Berryteuthis magister (Cephalopoda: Gonatidae), from the Japan Sea

Morphological and genetic variation of the gonatid squid Berryteuthis magister from the North Pacific Ocean is analyzed. Geographical differences were observed between sexually mature squid from different parts of the species range. B. magister from the Japan Sea was clearly distinguished from other conspecific populations by distribution of several morphologic features: dorsal mantle length, nidamental gland length, fin length, and fin width. Genetic divergence D sub(N) between squid from the Japan Sea and from waters off the Kurile Islands was 0.044, as revealed from 26 protein-coding genetic loci. Significant allele frequency differences were observed at seven of 12 polymorphic loci, and gene differentiation F(ST) equalled 0.12. Data from morphology, genetics, geographical distribution, reproduction, and ecology suggest that B. magister from the Japan Sea constitute a separate taxon of subspecific rank. Berryteuthis magister shevtsovi subsp. nov. from the Japan Sea is described. The subspecies is small, with a large fin, a bicuspid lateral tooth on radula, and weak differentiation between the central and marginal suckers on the tentacular club. It breeds in spring, and produces a small number of large eggs. It leads a bathypelagic life in the Japan Sea at very low temperatures.