is present in California, there are pictures here from Hollywood.. I have yet to examine an unmaculated N.guttula but there is reference to the presence of a small red spot at the base of the elytral epipleuron in the dark California populations. I will do more investigating on this and see if I can get a specimen to image.

After looking at the info in (1), and here, as suggested by Guy, I'm pretty sure N. nigrita is the correct ID.

Yes, my error, sorry. I confused N. nigrita with N. obscurus.... So forget a part of my commentaries. I can't confirm or infirm the identification. But, judging on the species description of Anderson (Carrion Beetles of Canada ans Alaska), the pronotum of your specimen fit more with N. nigrita then N. guttula. So your first identification was probably good.

If it would be useful, I will keep the next specimens that come to the black light, should I be so lucky as to have one return.

Well anyway, I just noticed that I've make an error : N. obscurus didn't have black elytra.. so it's for sure N. guttula

The only illustration of N. guttula on BugGuide shows orange markings on the elytra, my specimen had all black elytra. Also, I just noticed that N. guttula is in California here.

Two forms exist of this species : one with orange marking like the picture, and one with totally black elytra like your specimen. If you look well, you'll also can notice that the one on the picture has the first segment of the antennal club orange when on your specimen this one is black (the color of this segment always go with the colors of the elytra). But it's yet the same species. At a time, the black version was considered like a separeted species (known as N. hecate) but it's no more the case. I don't know if one form is more common than the other...

at this image of N.nigrita at the California Beetle Project..

http://www.sbnature.org/collections/invert/entom/cbpphylogeography.php

I just downloaded Anderson & Peck. 1986. Geographic patterns of colour variation in North American Nicrophorus burying beetles (Coleoptera;
Silphidae). Journal of Natural History 20(2):283-297. I've not read the article in it's entirety but they indicate that almost wholly black specimens occur on the coast of California, so your ID may be correct. I've also added another photo that shows the antennal club better. Thanks again.