Carabidae - Pterostichus oblongopunctatus?

[JRsbugs]

Hi,

I think I have tracked this one down to Pterostichus oblongopunctatus, I have checked all the details as shown on wcg and the pics seem to show them all.

I had the size down as 8mm but at a guess, taken on 5th May. It didn't look very well.

http://thewcg.org.uk/Carabidae/0480G.htm

Janet

[serendipity]

ok im going to ask what is probably a real stupid question! but how do i get to browse that wcg site? links to pages are often on here but i cannot browse from them or even on going to the homepage! nor can i find any info on home page. looks really useful to! do i need to join something?

[JRsbugs]

Here's the thumbnail page!

http://thewcg.org.uk/pages/thumbnails.htm

[Dogghound]

I agree Pterostichus oblongopunctatus. Usually associated with woodland was your's in your garden?

[JRsbugs]

Originally Posted by Dogghound

I agree Pterostichus oblongopunctatus. Usually associated with woodland was your's in your garden?

Great!

It was near my back wall, but there's trees all around and I have a huge Horse Chestnut tree in my garden, by huge I mean huge at least 40 feet tall.

[Paul mabbott]

I don't think this is pterostichine. Looks pretty much like Nebria brevicollis ....

[Dogghound]

Originally Posted by Paul mabbott

I don't think this is pterostichine. Looks pretty much like Nebria brevicollis ....

Any pointers Paul? Im really trying to get into these carabids a group ive put off for a long time.

[Paul mabbott]

Originally Posted by Dogghound

Any pointers Paul? Im really trying to get into these carabids a group ive put off for a long time.

On these pictures the main pointers are the colour and the pronotal shape. This is clearly brown whereas most of the larger Pterostichus spp are jet black and shiny. The forebody of Nebria (and Leistus) are quite domed, heavily pitted/sculpted and short (i.e. broader than they are long. The striations on Nebria elytra are deep and there are no dorsal pits. There are other clues but I can't make them out here.

The problem with ground beetles, especially the larger genera (especially Bembidion, Amara, Harpalus & Pterostichus) is that there are so many of them differentiated by subtle features that they can't reliably be identified without a lens/microscope.

Incidentally, Pterostichus madidus is the most recorded carabid in UK but Nebria brevicollis is probably more abundant.

[lync]

Originally Posted by Paul mabbott

The problem with ground beetles, especially the larger genera (especially Bembidion, Amara, Harpalus & Pterostichus) is that there are so many of them differentiated by subtle features that they can't reliably be identified without a lens/microscope.

Glad to see someone, yet again, re-emphasising this crucial point

[JRsbugs]

Originally Posted by Paul mabbott

On these pictures the main pointers are the colour and the pronotal shape. This is clearly brown whereas most of the larger Pterostichus spp are jet black and shiny. The forebody of Nebria (and Leistus) are quite domed, heavily pitted/sculpted and short (i.e. broader than they are long. The striations on Nebria elytra are deep and there are no dorsal pits. There are other clues but I can't make them out here.

The problem with ground beetles, especially the larger genera (especially Bembidion, Amara, Harpalus & Pterostichus) is that there are so many of them differentiated by subtle features that they can't reliably be identified without a lens/microscope.

Incidentally, Pterostichus madidus is the most recorded carabid in UK but Nebria brevicollis is probably more abundant.

Thanks Paul, on looking carefully at that one I can see they are very similar! I see the pronotum shape is a little shorter. The colour is tricky as P. oblongopunctatus is stated on wcg as:

9.5-12.6mm. Very shining black with faint metallic lustre, brassy or rarely bluish or greenish

There are two other main pointers I have picked out from the description of N. brevicollis, one is the setae on the hind angles of the pronotum which can be faintly seen as a long hair protruding directly upwards. If you enlarge the second pic these can just be seen, and the far one can be seen in the 3rd & 4th pic.

The second is the mention of setae on the tarsi:

each segment of meso and meta tarsi with several (basal segment up to 10) pairs of fine setae or pores

I had looked at these and wondered, but as it mentions for other species they are not always clearly stated.

Some good pointers there I think, and a good exercise in recognition.