Byturus ochraceus vs. tomentosus

Seeing a Byturus in the uploads by Claude yesterday made me realize I have these images on waarneming.nl and had been planning to add an English version to JD but hadn't gotten around to it ... so here it is - a tad Q&D, but hey :o)

The two western European Byturus species can be very hard to tell apart, especially from photo. Both are quite variable in colour and the colour changes during the season as the beetles mature more (the beetles become darker and duller), so this is a very unreliable character for ID(!)
Better characters are the male genitalia, size and density of punctures on pronotum and elytra (hidden under the dense hairs), width of the explanate margins of the pronotum (also often obscured by hairs) and the size of the eyes versus the distance between them. Mostly, only that last criterion is visible on photos.