Pseudocalanus newmani was originally described by Frost in 1989 from multiple samples caught in the main basin of Puget Sound.

Additionally, the male lacks sensilla on the mediodorsal portion of the second to fourth urosomal segments.

[1] Pseudocalanus newmani is found in the Arctic, the northern Pacific, and in the Atlantic off of the eastern coast of Canada and Maine.

The period of reproduction and growth corresponds to the time when water temperatures are lowest at the top 100 metres (330 ft) (around 10 to 12 °C (50 to 54 °F)), and the abundance of phytoplankton reaches its maximum.

This, along with a lack of large lipid stores, likely indicates that it cannot migrate to cooler waters and enter diapause.

The reason for this is because of predators (such as omnivorous copepods that have normal diel vertical migration) being more abundant during the night.

[8] But, when predators are found at the surface during the day, P. newmani experiences normal diel vertical migration.

[10] Pseudocalanus newmani is mainly herbivorous,[4] and feeds continuously, with an increased intake during the night.

Three-spined stickleback, juvenile chum salmon, and other planktivorous fish can attack this copepod.