Leptodiaptomus ashlandi is a calanoid copepod zooplankton native to the Laurentian Great Lakes and their basin.

Leptodiaptomus ashlandi is a zooplankton species widely distributed across Canada and the northern half of the United States in large deep lakes.

[1] Adult females of L. ashlandi can be distinguished by their two-segmented urosome and asymmetrical, rounded metasomal wings.

[2] This species is morphologically similar to other leptodiaptomids (Leptodiaptomus minutus, L. sicilis) and skistodiaptomids (Skistodiaptomus oregonensis).

Leptodiaptomus ashlandi are known prey items for a number of native and non-native Great Lakes fishes.