Ancistrocerus parietinus?

JRsbugs · #1 (**permalink**) 05-07-2011, 06:11 PM

Hi,

I checked all the patterns on this female with the specimen on this Belgian site, the face looks to be a match as well as the other patterns.

I also checked it on Biolib..

BioLib - Ancistrocerus parietinus

As mine was ~15mm, the size easily fits this species and as it was collecting a 'mud' sand ball to plug it's nest I thought it was fairly safe to call it Ancistrocerus parietinus.

Is there another species this could be?

Janet

Matt Smith · #2 (**permalink**) 05-07-2011, 08:17 PM

Ancistrocerus can't be positively ID's on body patterns, you need to examine the insect under a microscope for a confident ID.

JRsbugs · #3 (**permalink**) 05-07-2011, 08:26 PM

I guess that means genitals Matt?

I wonder why, as no other Ancistrocerus I have looked at looks like this one.. the patterns are a very good match.

I know some species of other insects or beetles have very small differences, but even those can often be identified if the relevant part is visible. What needs to be seen? I have quite high resolution pics which can be cropped but I think enlarging them again on here would be not much different.

eucera · #4 (**permalink**) 05-07-2011, 09:21 PM

Couplet 7 in Richards deals with female Ancistrocerus spp.:

- Sides and posterior surface of propodeum shining between ill defined punctures and rugae. Large species, length 13.0-16.0mm (plus a whole suite of variable colour characters including brown tarsi) A. antilope

- Sides and posterior surface of propodeum shagreened or granulate, not shining. Usually smaller species (Other spp including A. parietinus).

These are the characters I am referring to and (doubtless) the ones Matt alludes to as well since I am confident that he uses Richards key. Now... these simply can not be recognised clearly in any of the pics. That being said... I think I can see some brown tarsi...and some shininess on the propodeum of your specimen. However, without comparative material, and a close, microscopic study, I wouldn't be comfortable putting a name to the specimens.

JRsbugs · #5 (**permalink**) 05-07-2011, 09:45 PM

Thanks Stuart, I really need all sorts of keys!

I have lightened the area showing the propodeum, in the link it explains that area..

Ectemnius continuus (Fabricius) (a solitary wasp)

Does it look shiny now? The size seems to be a stumper but the propodeum looks granulate to me. My insects are organic, they seem to be getting bigger every year.

eucera · #6 (**permalink**) 05-07-2011, 09:53 PM

To be honest... I can't see any real detail and this is an absolute clinching character. I'd also like to compare this with accurately named specimens so as I can see precisely what the key actually means in practice. Without these things,I wouldn't like to give a specific name to the specimen.

You may well be right... but I am not confident that I can confirm this!

JRsbugs · #7 (**permalink**) 05-07-2011, 10:07 PM

The only specimen I can offer from the back view is the one on the Belgian site, the pic enlarges and although not the best it does look to be grainy on the propodeum. Checking the black marks on the legs they are identical too.

http://users.skynet.be/fa968040/EUME...parietimus.JPG

Matt Smith · #8 (**permalink**) 06-07-2011, 12:08 PM

Google up some images of Ancistrocerus nigricornis, you will find a lot of photos that look very similar to the colour patterns of the wasp you have in your photo.

Patterns on some of these small wasps can be be very variable, a good example are the males of Cerceris rybyensis, they can go from one almost one extreme to the other regarding the relative proportions of black and yellow on the abdomen.

The level of detail we need to see is around the 20-40x magnification. "Shining" is a difficult charecter to judge from a photo as the lighting levels can vary so much and a "shine" can be an artefact of overall reflection of the whole surface. As Stuart said, a comparative check under identical lighting conditions is what is needed.

JRsbugs · #9 (**permalink**) 06-07-2011, 01:18 PM

True, A. nigricornis does look very similar Matt.

But, the specimen on the Belgian site of a female has an extra pair of spots on the propodeum. I don't know if this is variable, but the tibia are all yellow where mine has black areas at the apex of all mainly on the posterior.

http://users.skynet.be/fa968040/EUME...ricornis_F.JPG

The face is very similar but the yellow spots near the mouth look to join and are larger but again could be variable.

http://users.skynet.be/fa968040/EUME...cornis_F_T.JPG

A. parietanus does have the black areas on the tibia..

http://users.skynet.be/fa968040/EUME...parietimus.JPG

The spots near the mouth aren't joined, I can see those on mine are not joined.

http://users.skynet.be/fa968040/EUME...rietimus_T.JPG

Checking a specimen of A. nigricornis on Biolib, these characters obviously can't be used!

BioLib - Ancistrocerus nigricornis - Image

One thing I have noticed is the shape of the bottom of the propodeum in A. nigricornis is straight, on mine it has noticably angled edges. I would think this is a good character to use? Is it mentioned in the keys? If there's a reasonably priced key available I think I'll get one, any recommendations?

Jason Green · #10 (**permalink**) 07-07-2011, 09:09 AM

Morning Janet,

The edges of the propodeum's bottom-corners are simply obscured by hairs. As said, markings can vary.

Look up 'Scolioidea, Vespoidea and Sphecoidea' by Richards (Print Date 1980) - about £15 from the online shop that shares it's name with a famous rainforest. Then there's the New Naturalist one, but have no experience with it.

As said though, you do need a specimen to examine under good lighting, or even with the book you'll be no closer as far as certainty goes than you are here. Basing IDs on colour-patterns is risky and wouldn't be accepted by the Eumenine Recording Scheme.

Take care,

Jason