Enochrus melanocephalus

One of my first attempts at identifying an Enochrus led to an ID of melanocephalus, but upon reviewing my Hydrophilidae records recently it was immediately clear that this was a misidentification. So it was good to find a real one 2-3 months later. The very black legs and underparts set this apart from other Enochrus I've seen, although it was the proportional length of the maxillary palp segments that clinched the ID.

Enochrus melanocephalus showing scutellum, maxillary palp and underparts, Wendling Beck Environment Project (Norfolk, UK), 9th August 2023

This came to light a couple of fields away from the one above. Although I suspected it was Enochrus I keyed it to make sure, but as the apical maxillary palpomere was longer than the subapical one, it keyed to Hydrobius. That was clearly incorrect, and as the apical palpomere was only very slightly longer than the subapical one I tried the alternative option and that led to Enochrus as expected. It was the same character that then firmly placed it at melanocephalus, the other Enochrus all having shorter apical palpomeres.

Enochrus melanocephalus showing hind tarsus, maxillary palp & antenna and sutural striae, Wendling Beck Environment Project (Norfolk, UK), 16th June 2025