Moved to Brachinus elongatulus.

Another new one for the guide. I'm really glad you're identifying the specimens, otherwise all these Brachinus would stay in the genus page.

based on the combination of my microscopically testing this specimen against the key to North American Brachinus by Erwin (1970) plus the subsequent opinion by Terry Erwin (pers. com.) that this image best fits B. elongatulus. This species belongs to the Brachinus texanus species group sensu Erwin (1970). Differing from very similar B. texanus, B. elongatulus has notably a limited southwestern range; elytra distinctly broader (but equally elongated) and with more prominent costae (glabrous longitudinal ridges); color of elytra with bluish reflection (may not be visible at all angles, not grey-greenish); tarsi more likely to be darker. In this specimen the styli of the female ovipositor are rounded apically ending in obtuse points, not acutely narrowing as in female B. texanus. Another image that shows body proportions of B. elongatulus, notably the broad elytra, is posted here.