The Forêt de Sare is home to the Carabus lineatus, as well as Carabus splendens, a closely related species. Generally 'lineatus' has more pronounced blackish elytral lines, but some specimens are almost indistinguishable in the field from Carabus splendens. The only exclusive features are the longer 'wing membranes' (found under the elytral shield) from lineatus, where 'splendens' has shorter triangular reduced 'wing membranes'. The penis of the male can also reveal with certainty the species. Generally there are only few carabus species that are very difficult to distinguish in the field. The main reason for this case is that Carabus lineatus is considered as an old 'genetic fusion' between Carabus lateralis (a more southern species found in Portugal and Spain) and Carabus splendens (found in the north of Spain and southern France). Carabus lineatus has a distribution in between these two species. It reaches it's northern edge in the French Pyrenees Atlantiques. Especially in this oevrlapping range with 'splendens', lineatus shows often strongly reduced elytral lines, which makes sometimes almost indistinguishable in the field from 'splendens'.
This individual shows some external features wich indicates a 'lineatus' , such as slightly more pronounced elytral lines, and strong punctuation on the back of the elytra and along the elytral lines.