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Centrodera - Centrodera spurca - male

Centrodera - Centrodera spurca - Male
Aptos, Santa Cruz County, California, USA
August 2, 2006
Seems likely this is Centrodera spurca. My hesitation is that Evans & Hogue(1) state that C. spurca is a montane species (in Sierra Nevada, Transverse, and Peninsular ranges) whereas this one was near sea level in coastal oak woodland (with nearby redwoods and douglas fir), which corresponds better with the range they mention for the similar looking C. autumnata. However, larger size and "depressed, recurved pubescense of the elytra" are given as distinguishing characters of C. spurca, which I believe apply to this individual. Maybe an expert having familiarity with the genus will be able to shed some more light?

This individual was found in the house, and placed on the leaf for the photo. Very docile and good-natured beetle.

Images of this individual: tag all
Centrodera - Centrodera spurca - male Centrodera - Centrodera spurca - male Centrodera - Centrodera spurca - male Centrodera - Centrodera spurca - male Centrodera - Centrodera spurca - male

Moved from Centrodera.

That would help.

Didn't measure!
Wish I had, it was very cooperative. I took the photo before I was more attuned to the subtleties of IDing beetles...and I'd seen a similar looking photo of C. spurca in Milne & Milne(1) so figured I knew what it was.

I recall it being fairly large, I'd guess more in the range of 20-30mm listed for C. spurca than the 14-22.5mm range listed for C. autumnata in Evans & Hogue(2). But that's just a guess, I was hoping some other visual or gestalt character might be apparent to someone. Evans & Hogue(2) state there are 9 Centrodera taxa in California, though only 3 are briefly discussed there.

...can't make a call. Centrodera spurca differs from C. autumnata in the elytral apices dentate at the suture, depressed versus suberect setae at the basal portion of the elytra, males with pubescence of outer antennomeres smooth rather than bristling, and larger size. Unfortunately, none of those characters are really visible in this photograph. There is some size overlap, so a definitive measurement would be needed. Centrodera autumnata is a coastal species, but I don't know if C. spurca is absent from the coastal areas.

One other California species of Centrodera (C. dayi) looks similar to C. autumnata but has the tarsi shorter - I don't think this individual represents that species.

Great info!
Many thanks Ted...the details you provided are much appreciated (more so than simply making an authoritative call, since with it I and other BugGuide readers can learn the reasons :-) I have more images of this specimen which may help evaluate some of the characters you've mentioned. I'll post them soon. (The images can be frassed if they don't help.)

Two brief questions:

1) Can we assess whether this is a male from the available images?
2) Any chance the two black dots at the outer edges of the elytra (~2/5 distad from base) can separate C. Spurca from C. autumnata?

[Postscipt: OK, I posted five more images to help address Ted's remarks.]

...the detail photos provide the information we need - it is Centrodera spurca. The individual is a male, based on the length of its antennae relative to the body (females have shorter antennae and more robust body). The closeup of the elytral base clearly shows the depressed vestiture, and the closeup of the distal antennomeres shows the smooth rather than bristling pubescence. The elytral apex photo is not as conclusive, but I think I can make out the dentate sutural angles (where the elytra meet). Assuming the size is as you recall, everything points to Centrodera spurca.

I suggest retaining the elytral base and distal antennomere detail photos, as they were most helpful in the diagnosis.

The black lateral spots on the elytra are not diagnostic, as all three of the species I mentioned in my earlier post exhibit them.

Nice Work
Thanks Ted. That was fun & informative! I'll move this set to the species page and frass the less diagnostic images.

However, I do still have some confusion regarding the meaning of "depressed vestiture" here. I presumed it referred to a condition where the base of the hairs would emanate from within a small pit. I don't quite see that looks to me like there are small disks of elevated "fine scurf" at the base of the hairs. Maybe it's just an optical illusion effect for me (disks popping out vs. in)? If you could clarify this, you might have me on the way to believing in Santa :-)

"Depressed vs suberect"...
...vestiture refers to how the setae stand, not the punctures from which they arise. Thus, "depressed vesiture" is pubescence that lays flat or nearly so, while "suberect" setae stand more erect.

The "fine scurf" you refer to may be an optical illusion - each seta arises individually from a single puncture.

p.s. "setae" = "hairs", but as we all know only mammals have hair ;-)

Now I get it!
I was confused because I'm accustomed to using the term "appressed" for setae pressed against or parallel to a surface. I guess "appressed hairs" is the term favored in botanical usage (my background), so I erroneously presumed "depressed setae" referred to some other nuance. Indeed, motivated by your response I checked the glossary of my "entomological bible" Borror et al(1), and found the term "depressed" as you describe it, and no entry for the term "appressed".

Good to have it all sorted out. Thanks again, and a Merry Christmas to you :-)

...refers to setae that actually lay flat against the integument, while erect represents the opposite condition. Depressed and suberect represent conditions intermediate between those two extremes. Some people may think I like to quibble about terminology, but as you see it can make a difference.

Happy holidays ;-)

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