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Tragidion densiventre? - Tragidion densiventre - male - female

Tragidion densiventre? - Tragidion densiventre - Male Female
Montosa Cny, Santa Cruz County, Arizona, USA
September 27, 2008

Thought all might enjoy...
...this summary of the whole mess. There should be no doubt now as to what is T. densiventre and what is T. deceptum.

This is T. densiventre
Ted had the illustrations from the original paper(which he reviewed) for T. deceptum on his web page (with permission), but he had the T. densiventre male posted with the deceptum female. This led me to believe that my photo showed the new species, and I posted it as such. Ted then pointed out that mine were T. densiventris, so to clarify my earlier wrong ID, I added the photo that I believed was published in the public realm(I found it originally on flickr without any source or copyright attached. This one still shows the wrong male that confused me). So to look at the now corrected photo of T. deceptum on Ted's webpage go to

Thank you Margarethe...
...for clearing this up. I'm sorry for the confusion I created, but I'm also happy that the error was found and that the correct illustration of this species is now posted on my website.

I've really learned a lot today...
and I think I can even tell the difference in the field now. Except, I've never seen any Tragidion higher up in the mountains. I'll keep looking

Go to...
...Peña Blanca Lake. That's where I collected a nice series of T. deceptum feeding on sap oozes of Baccharis sarothroides. I also collected one up near Onion Saddle in the Chiricahuas. I bet some fermenting bait would bring them in.

Lovely photos, Margarethe!
I read Ian's paper last year October & will try to see another new sp. (T. agave) this summer.
Might be T. densiventre, I'd have to take a look at the paper.
I suggest to send these directly to Ian at Placerita Canyon.
In T. annulatum the elytral costa extends to the apex; the dark band at the base of the elytra is much narrower than on deceptum.
As for densiventre, the elytron has five ribs, or costae, all the others have four, acc. to the key (Swift & Ray, Zootaxa 1892, 2008). I do count five on your beetles when enlarging the photos.

I'm pulling out the specimen
to count right now! Ok, I think there are five, but I wished I had one with four to compare to.

do you have the Swift & Ray paper? If not, I'll e-mail you a PDF. I think this will clear up much.

I only have the review
I'd be grateful for the pdf!


By the way,
the male also has the red tibiae seen in some T. densiventre.

A review of all my specimens
A review of all my specimens from southern AZ showed them to be T. densiventre.

Mine, too

...only one of the specimens I've collected in Arizona is Tragidion densiventre (lower Madera Canyon). All the rest are T. deceptum from around Peña Blanca Lake and high up in the Chiricahuas.

Among my material, both males and females of T. deceptum have the antennae annulate, while only the males of T. densiventre have the annulations (females have all black antennae). Swift & Ray don't mention this in their review, so I don't know if it holds up with all specimens, but I don't recall ever seeing females of what is now called T. densiventre with annulate antennae.

The female in this photo above
actually had annulate antennae if you enlarge the original (life) photo. Not as clearly as the male however. On the dried specimen they look quite black. This is my larger file on flickr

The photo is marked private, but I'll take your word for it.

I took a look at the photo...
...original size - very nice! A beautiful female of Tragidion densiventre. Yes, there is a faint indication of annulations in the antennae, but in all the females I have of T. deceptum the annulations are quite distinct.

Might I ask how you achieved such a white background while retaining the shadows for the legs and antennae? I like that look.

This is fantastic, great job!
This is fantastic, great job!

Do you know what the key char
Do you know what the key character is that separates T. deceptum from annulatum?

No, but I think they are
populations completely separated by geography and thus by definition separate species. But read on what Ted Mcrae remarked under the ones that I had moved to T. deceptum. If you look at the type (that I've copied from the original publication) and the male in my photo - can you tell the difference that he sees?

In the mammal world, populations separated by geography are subspecies until they diverge significantly. For example, the Mount Graham Red Squirrel is classified as a subspecies of the (American) Red Squirrel, Tamiasciurus hudsonicus grahamensis. It is one of many animal populations cut off from the rest of the species' range by global warming around 10,000 years ago. It looks a little different, but it's close enough to be one species.

Are you suggesting...
...that T. densiventre and T. deceptum must be subspecies because they look so similar? Swift & Ray (2008) provided numerous morphological characters that distinguish the two, and their biologies and habitat preferences differ as well. This is strong evidence of genetically-based isolating mechanisms. Sometimes species that look very similar are found to be quite distinct only after sufficient series of specimens from across their ranges of distribution become available for critical study.

Division is not enough
No, I'm not saying looking similar is enough to count them as the same species. I was responding to the statement that isolation alone was sufficient to make them separate species.

...I missed that comment.

My apologies...
...I erroneously put the male of T. densiventre with the female of T. deceptum in the illustration of the "type" that Margarethe has linked to. If somebody can find a way to delete the photo, it would be much appreciated. I now have posted on my website a corrected illustration of the male and female of T. deceptum.

So yes, Margarethe, your specimens represent T. densiventre.

My apologies for the confusion.

I've deleted the photo

The costae seem more prominen
The costae seem more prominent in your's than in the deceptum picture.

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