First description of Metridia okhotensis Brodsky, 1950 (Crustacea: Copepoda) male, with female, fifth copepodites, and notes on distribution in British Columbia inlets

Abstract

The male of Metridia okhotensis (Copepoda: Calanoida) is described here for the first time. It can be separated from similar species, including M. longa, a morphologically similar species found in the Atlantic and Arctic oceans, on the basis of body size, the relative length of the first antennae, and the shape of the fifth leg. Here we describe both the fifth and sixth copepodite stages of male and female M. okhotensis, and present a tabular key to members of the genus reported from the northeast Pacific Ocean. In addition, we show that M. okhotensis is widely distributed in the protected waterways of the British Columbia coast, and at times and in some places it is numerically dominant. Particularly high numbers are found in Loughborough and Portland inlets and Douglas Channel. The size of the copepod and of its population suggest it plays an important role in the zooplankton dynamics of British Columbia nearshore waters.