Taxonomic Status of the Okhotsk Lumpsucker Eumicrotremus ochotonensis (Cyclopteridae, Cottoidei) with Redescription of E. derjugini

Abstract

The species status is justified for the Okhotsk lumpsucker Eumicrotremus ochotonensis based on the morphological characters. The differences from the closely related species E. derjugini inhabiting the Arctic Ocean are given. Two species were redescribed basing on type series, their diagnoses were clarified, and the lectotypes were designated. Intraspecific variability is discussed using new materials from the Barents, Kara, Laptev, and Okhotsk seas. The two species differ markedly in a complex of morphological features (shape of the submerged dorsal fin, proportions of the body, number and location of bony plaques) and characteristics of biology (spawning season). The modern disjunction of the ranges of E. ochotonensis and E. derjugini covers the Bering, East Siberian, and Chukchi seas. Sequence analysis of the cytochrome oxidase (COI) gene fragment of mtDNA revealed differences in the haplotypic diversity of the two species. Weak genetic divergence between species indicates a relatively recent isolation of E. derjugini and confirms its status of the evolutionary young species.