Explanation of Names
Harpalus texanus Casey 1914
externally very similar to H. pensylvanicus, reliable distinction is possible only by careful examination inside the aedeagus. Ball & Anderson (1962) described the diagnostic microscopic structures of the everted internal sac. The females are reliably identified by their association with captured males.
Bypassing the demanding procedure for everting the internal sac, I (PWM) examined instead the more accessible apex of the aedeagus which in texanus appears to be naturally exposed in many specimens. Morphology of the apex in combination with the other features noted below should provide a reasonably diagnostic approach for H. texanus vs H. pensylvanicus.
(1) Aedeagus with apical shaft wider; extreme tip rounder, bordered ventrally by a thin smooth elevated lip against proximal rough area vs apical shaft narrower; extreme tip more pointed, without defined lip;
(2) Pronotum with basal groove more or less interrupted by punctures laterally, but not consistently so and never extensively interrupted vs basal groove extensively interrupted;
(3) Both sexes with shinier elytra (best appreciated under microscopy) vs duller luster;
(4) Pronotum slightly more constricted toward base vs base wider;
(5) Pronotal base with areas around depressions more convex and less uniformly punctate vs flat portion across base larger, extending anterolaterally to sides more widely flattened, punctate coarsely and uniformly;
(6) Body slightly broader vs narrower;
(7) Restricted to Coastal Plain from NC to TX vs likely occurs sympatrically near the same coastal areas plus the eastern half of North America.