Antennal scrobe distinct and narrow (P. navigans)

Antennal scrobe distinct and narrow, shallow but capable of receiving the entire antennal scape in repose (a); bordered by strong, unbroken frontal carina mesially (b); depression marked by a continuous smooth surface entirely (or nearly entirely) uninterrupted by rugulae (major worker). Diagnostic character for separating P. navigans from P. flavens.