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Photo#873715
Macrosiagon pectinatum? - Macrosiagon octomaculata - female

Macrosiagon pectinatum? - Macrosiagon octomaculata - Female
Santa Cruz River, Amado-Montosa Road, Santa Cruz County, Arizona, USA
July 26, 2013
This ripiphorid was found by Emily Coin during the 2nd day of the AZ BugGuide Gathering. It was nestled amidst the foliage of a clump of mule-fat (Baccharis salicifolia) in the Santa Cruz River wash. It's the same individual as in Alice's post below:



The monopectinate antennae clearly indicate it's a female. Alice, in her post, noted the mass of eggs within the curled leaf just below the ripiphorid...also visible here as a white blur. I don't know for sure whether those eggs were laid by this beetle, but my photo was taken shortly after Alice's, and I think I can see more eggs in my image than I can see in Alice's...though that may just be a result of the different angle. It's of interest that Zack Falin's detailed discussion of Ripiphoridae in (1) includes remarks on Macrosiagon stating "eggs are laid on undersides of leaves, in crevices in soil, and on flowers of Asteraceae" (see bottom of page here). The beetle flew off soon after I snapped two quick photos. I don't think any of us noticed the eggs at the time...as we were distracted in trying to track our fleeing quarry.

I ran this ripiphorid through the keys in Rivnay(2)(1929), Vaurie(3)(1955), and Linsley & MacSwain(4)(1951) and cross-referenced with the discussions there, the description here, and resources elsewhere. Based on studying those ref's, and BugGuide images and comments, I'm fairly confident this is Macrosiagon pectinatum. The rounded vertex and black head here rule out M. sayi...in that species females have red heads; the vertex is truncate; and (key character) the distal end of first segment of hind tarsus is produced...or obliquely truncate...depending on the angle of view (see Fig. 18t here).

Rivnay (1929) listed numerous synonyms for M. pectinatum, and Vaurie(3)(1955), Linsley & MacSwain(4)(1951), and Falin(1) emphasize that M. pectinatum is a highly variable species...or likely a "species complex" that will eventually be sorted into more than one taxon.

Images of this individual: tag all
Macrosiagon pectinatum? - Macrosiagon octomaculata - female Macrosiagon pectinatum? - Macrosiagon octomaculata - female

Moved
Moved from Macrosiagon.

It appears I erred in my initial remarks above...this is M. octomaculata per Zack Falin's determination from Alice's post of the same individual...see comments here.

 
great find...
... wish I had seen it! (I think I was off trying to get photos of some flies while my field assistant was elsewhere--totally my fault.)

 
Agreed, nice find!
I was very grateful to your "field assistant" for finding it and notifying us :-)

 
Patrick...
I just bumped into this photo of the actual scene:



It shows me checking my viewfinder right after photographing the Macrosiagon, while Emily searches for more of them in the Baccharis bush.