Hygrotus sp. - Coelambus nubilus
Medford, (~25 miles east of Philadelphia, PA) Burlington County, New Jersey, USA
June 26, 2007
I believe this Dytiscidae is a Hygrotus species, due to the "Epipleuron with a transverse carina at humeral angle" (Am. Beetles), which you can see as "the raised line" on the elytra "shoulders" in this ventral image. This separates it from the big genus Hydroporus.
Keying using Downie and Arnett, appears to lead to H. dissimilis (Gemminger and Harold), which is listed as very widespread (even NJ). However, I can't find any internet reference to that species - none! So perhaps it's another mistake in D&A's book. If anyone has Larrson's book and could check that, I'd greatly appreciate it. Otherwise, corrections welcome, as usual :)
UPDATE: using Larson's ref. I found H. dissimilis as valid species. Hydro*porus dis*par LeConte is a synonym, the type of which is seen from MCZ. But from the type image, my beetle is clearly not it. Still, Hygrotus appears to be the correct genus.
came to UV light
Images of this individual: tag all