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Bee or fly? - female

Bee or fly? - Female
Yucca Valley, Sab Bernardino County, California, USA
June 11, 2020

Images of this individual: tag all
Bee or fly? - female Bee or fly? - female Bee or fly? - female Bee or fly? - female

Moved from ID Request.

Beetle [thumb:628994]
Looks most like vierecki but can`t see if there are serrations on middle tibia.

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Ripiphorus vierecki vs rex
Some or all of the beetles currently identified as Ripiphorus vierecki may be R. rex. Vaurie(1) notes that the two species are very similar. To distinguish them, Evans and Hogue(2) state rex "is unique among the species of Ripiphorus in having a serrated outer edge of the middle tibiae". Three beetles formerly under vierecki were recently moved to rex on this basis:....

I have posted images of a rex male's right middle leg showing the serrations in profile:

Note from the lateral full body view that if the serrations are not seen in perfect profile at high resolution, they appear as a series of dots due to their darker color. This appears to be the case for all three of the specimens remaining under vierecki:

This should be verified by an editor (who has access to the often higher resolution images as submitted). The first of these is a follow-up to photos of a different specimen on the same type of blossom and in the same location taken one week early and subsequently moved to rex for having more clear serrations. Evans and Hogue point out the Rhipiphorids are rare but may be locally abundant.

Before making any moves, though, note that Evans and Hogue is generally not a primary source, and the claim that only rex mesotibia are serrated in the genus is unreferenced. Does anyone know the source of this information? If it can be shown that vierecki too have serrations, a synonymy is suggested.

Finally, note my comment under Linsley and MacSwain(3), which may help explain the confusion.
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Contributed by Edward L. Ruden on 18 May, 2012 - 11:03pm
Last updated 19 May, 2012 - 10:29am

Two additional distinguishing characters?
The 1955 reference by Vaurie(1) mentions two more traits for distinguishing R. rex from R. vierecki:
1) a median carination of the dorsal segments of the abdomen; and
2) a densely hairy, elongate, projection on the inner side of the front coxae at apex.

I think the 2) is visible in the thumbnail below:

The last sentence in Vaurie's discussion of R. rex mentions that the description of Fall's AZ and NM specimens of R. vierecki agree very well with R. rex, except that Fall made no mention of characters 1) and 2) above.

Vaurie makes no mention of the serrate outer edge of the mesotibiae for R. rex...I guess that's something noted after her work by Evans & Hogue (and/or others?).

I tried to check whether I could see if all these presumed characters of R. rex were indeed absent in the MCZ type images of R. vierecki...but those images weren't loading in my browser when I visited the MCZ web site. (I've noticed the MCZ web site sometimes has periods of non-functionality...hopefully the images will be accessible later.)
… Aaron Schusteff, 21 August, 2012 - 12:44am
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Pictures added
I've added new views of my specimen, and describe them on my Main Page. They detail key features that may separate rex and vierecki in general (assuming they can be). It's clear though, that inspection of museum samples is needed. The published work is too ambiguous. If you succeed in locating some, I'd love to borrow a male and female of each if possible, and post a similar photo series for the set.
… Edward L. Ruden, 25 August, 2012 - 6:20pm
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Coxal projection
The medial carination is ambiguous on my specimen since the dorsal abdomen is laterally compressed from dessication. It does not seem to have a coxal projection such as the one you show. I will add a ventral view in the next few days to my series. This may be a key feature to distinguish the two species. Hopefully MCZ images will confirm this when they return.
… Edward L. Ruden, 21 August, 2012 - 9:51pm
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Zack Falin (pers. comm.) told me...
...that he used to treat the two as synonymous, but the issue deserves to be revisited: Bill Warner, for one, believes the two are separate species.
… v belov, 19 May, 2012 - 3:28pm
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Synonyms vs. Distinct Species
The more I study the literature, specimens, images, collection data, etc....the more things seem to point to synonymy of R. rex and R. vierecki. Lots of details, including links to original descriptions of both taxa (and many other relevant references) can be found accompanying this post, which shows specimens from the CAS collection labeled as R. knaussi (= R. vierecki), and that seem to key and conform to description details of R. rex.

It would be very helpful to learn from Bill Warner, or others who consider the species distinct, what characters or criteria can be used to separate them. There are a number of BugGuide posts that will be difficult to place without resolving this.

There are other problematic species groups in the genus as well...where separating out species based on the available literature can be quite difficult or impossible (e.g the "R. fasciatus group"). Happily, BugGuide is accumulating images of a number of these sure would be nice to be able to place them to species.

This is a fascinating genus, eminently worthy of a thorough, well-researched and well-reasoned treatment. It's been wanting of a solid revision for many decades, and presumably a much larger pool of specimens are now available for study in collections, compared to when earlier references were written.

Hopefully one or more earnest and insightful coleopterists out there will produce such a work in the not too distant future.
… Aaron Schusteff, 23 January, 2013 - 1:21am
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Synonyms vs. Distinct Species
As I was just slapping names on some of these things I thought I would chime in here directly...

In short, I still believe R. rex and R. vierecki are synonymous (though Bill has also mentioned to me in conversation that he believes there is a difference, though neither of us provided evidence to back up our assertions). Without re-hashing everything that's been written here, I'd like to point out just a few things.

First, R. rex was described from a single male, R. vierecki was described from only females- hence a lot of confusion (I'm not sure how Rivnay assigned R. rex to a species group according to female abdomen color [a horrific character to begin with] when the female of R. rex was unknown to him). The carination (or lack thereof) of the abdominal tergites is in my mind a bogus character and dependent on preservation. The odd little ventral projection of the procoxae is present in every male and female I've examined (more pronounced in males), and *every* male I've looked at appears to have some degree of serration (though it can be subtle).

I have dissected out the whackers for a number of Ripiphorus "species", but only enough to convince me that synonymy is rampant in the group; not enough to provide conclusive publishable evidence. And yes, this group and Macrosiagon cry out for modern comparative revision (including DNA evidence), though at my pace I kind of doubt I'll be the one to do it...

… Zack Falin, 8 March, 2013 - 2:00pm
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Thanks for your comments Zack
To add some extra data points...I examined a number of specimens labelled as R. vierecki at the Essig Musuem (UC Berkeley) a few weeks ago. They all had serrate mid-tibiae and pronounced ventral projections of the procoxae, as in R. rex.

At the same time, while R. rex is said to occur in CA, it seems quite odd that there are no specimens labelled as R. rex at the Essig, CAS, or any other major other CA collections (as far as I can tell from online searching)...yet all those collections list lots of specimens labelled as R. vierecki. What might explain this?