Phrynoponera is a genus of ants that has been studied extensively, particularly by the myrmecologist William Morton Wheeler. Some distinguishing characteristics of Phrynoponera ants, as noted by Wheeler and other entomologists, include:

1. Morphology: Phrynoponera ants typically exhibit a robust body structure. They have a distinctive head shape that is broader than it is long, with prominent mandibles that are often serrated.

2. Eyes: These ants usually have reduced or absent compound eyes, which is a trait often associated with their subterranean lifestyle.

3. Coloration: Phrynoponera species are generally dark in color, ranging from black to dark brown, which helps them blend into their underground habitats.

4. Worker Size: The workers are often polymorphic, with variations in size and shape that may reflect their roles within the colony.

5. Behavior: They are known for their unique foraging behavior and nest-building habits, often creating nests in soil or leaf litter.

6. Caste System: Phrynoponera ants exhibit a caste system that includes workers and reproductive individuals, with distinct roles and physical characteristics.

For a more detailed study, Wheeler's original works provide in-depth insights into the taxonomy and biology of these ants. If you're interested in specific species or additional behavioral traits, please let me know!