What term describes ant species in which all workers are the same size?

The term that describes ant species in which all workers are the same size is "monomorphic." This term specifically refers to organisms that exhibit a single form or size within a given species or group. In the context of ants, monomorphic species have worker ants that are uniform in size and shape. This is in contrast to polymorphic species, where different forms, sizes, or castes exist within the same species, such as small workers, large workers, and winged reproductives.

Understanding the differences in these terms is crucial for recognizing the diversity and complexity of ant societies and their adaptations to various environments. Monomorphic ants often exhibit different behavioral or ecological characteristics due to their uniform size, which can influence their foraging strategies and colony dynamics.