173 Delta Quadrant species[]
In 2375, Seven of Nine gave Bridge assistant Naomi Wildman sociological data on one hundred and seventy three Delta Quadrant species to study. (VOY: "Infinite Regress")
These species were only mentioned in dialogue.
Given the nature of the data, these species are likely sentient, but not necessarily humanoid. This number likely includes all known species USS Voyager had already encountered up to that point, plus other unmentioned species.