This specimen is housed in the Essig Museum of Entomology at UC Berkeley. The collection date of this specimen was hard to determine, it appeared to say "Y-2-50" which I took to be a potential X, hence, 10/2/1950.

I had always wanted to see Chlaenius fuscicornis, as I had seen dozens of Chlaenius erythropus and was afraid of misidentifying a female specimen. Luckily, the difference described by Bell in his 1960 revision of the genus held up well when viewing this specimen.

The pronotum is clearly less sinuate than in C. erythropus, and antennomere 3 is very dark relative to 1 & 2 (though it is lighter at the basal end). The legs are not as dark as I had expected, as I'd seen a great variation in the degree of darkness/lightness in the legs of C. erythropus.

Bell described the best way to distinguish the two species through observation of the aedeagus, as the aedeagus of these two species are drastically different. Interestingly enough, Bell describes a closer relationship of Chlaenius fuscicornis to C. laticollis as the aedeagi are more similar.

det. R. T. Bell