What characteristic distinguishes Nevada dampwood termite nymphs?

The distinguishing characteristic of Nevada dampwood termite nymphs is that they have a dark abdomen. This feature sets them apart from other developmental stages of termites and aids in their identification. Nymphs are immatures that have not yet developed into adult form, and while they can share some similarities with adults, the coloration can be a critical identifying trait. The dark coloration of the abdomen helps differentiate these nymphs from other termite species that may have lighter or differently colored abdomens.

The other characteristics presented in the options do not align with the typical traits of dampwood termite nymphs. For instance, bright orange coloration is not typical, nor are dark abdomens indicative of other phases or species of termites. Additionally, all termite nymphs possess legs as they are part of the developmental progression toward adulthood. Nymphs are not significantly larger than adults either; in fact, they are smaller but grow larger as they approach maturity.