ID confirmed by Claude Tessier
Is this Dytiscus dauricus
? Seems to fit the description, but I've never seen one before. (metacoxal lobes acuminate; ventral colouration pale with expanded black markings on abdominal sterna; pronotum broadly rimmed with yellow; sulcate females of D. dauricus have ridges 7 and 10 fused apically but 8 and 9 not fused)
Unable to give exact date (sometime between afternoon of May 31st and the morning of June 4th). Co-worker found it dead in his truck today (June 4th, 2014). Assures me it wasn't there prior to June (cleaned his truck out on the 31st of May) and that he's only been in the Fredericton area.
If my ID is correct, then it is a new BugGuide record for New Brunswick.