Ichneumon and other beasts.

I took a small clump of Cocksfoot Dactylis glomerata from the Wee Wood the other day. And then I took another one from by the Loch of Stenness when I went to Brodgar the day after. The clumps were cut off from the base and would just fit in a dog-poo bag. Once home I warmed them up and then started to pull them apart on a white tray. I've tried this before but I attempted much too large clumps of the grass and didn't get to the base of them, most probably, I wasn't too successful in the past anyway.

Conversely this was a very successful exercise. The clump from the Wee Wood produced Barynotus moerens, a couple of Tachyporus chrysomelinus, a Stenus that I haven't done yet, and quite a few Tachinus that look as if they represent at least two different species.

Barynotus moerens, a not uncommon, large weevil. Reidentification, thanks to Mark Gurney, I need to check all of these against the guides - Otiorhynchus singularis, most likely.

Tachyporus chrysomelinus.

The Tachyporus is a slightly tricky ID from T. dispar but they can be split, I believe, on the number of setae on the apical border of each elytra. Mine had four setae, rather than three, so T. chrysomelinus is apparently what they are. The habo fits better for that species as well.

I'm looking forward to tackling the Stenus from that sample, I enjoy doing those. There were of course a pile of Aleocharines and various very tiny 1mm beetles, I'm not so looking forward to all of those.

The sample from near Loch of Stenness held a bit more variety, Aleocharines, tiny wee things, but also a carabid, Calathus melanocephalus, another different Stenus - fuliginosus, a tank-like 2mm Micropeplus fulvus and star of the show an Ichneumon.

I had a look at Bioimages and reckoned the Ichneumon was indeed an Ichneumon sp and perhaps albiger. But these are very tricky, I posted a few quick snaps and KL suggested I needed to eliminate gracilentus. I was pretty pleased I'd got the correct genus, let alone that close. But this is a very tricky split. In its favour as albiger, small size, 8.6mm and extracted from a grass tuft. Against, NBN distribution (maybe) and perhaps a little lemony tint to the scutellum. I tried Hilpert's key but it is hard. I posted some more images and KL helped some more. I then went back to Bioimages, examined both species again and looked very critically at T2 and took some more photos. In the end I think it is Ichneumon albiger but it probably needs the specimen examining to be 100%.

Rather a lot of images follow:

Live, female.

Face.

Thorax dorsally.

White spots on T6 and T7.

Hind coxa dorsally.

 

 

 

 

Thorax, T1 and T2 laterally.

Are there any striations between the gastrocoeli at the base of T2?

Looking carefully on Bioimages and comparing with microscope views of the two species I think this is Ichneumon albiger, female, with no striations. In case of either species this will be new for Orkney. (Confirmed from specimen as Ichneumon albiger, many thanks AC).

Much easier from that clump of grass were these:

Stenus fulvicornis.

Calathus melanocephalus.

Micropelpus fulvus, staphylinoides (thanks for help CW, got there in the end!) all of 2mm long. (Note, important with these to check laterally to see if there is a tooth near the dorsal apex of the abdomen.)

Not a very good image but you can see the obvious tooth making this M. staphylinoides, fuscus has no tooth.

Having a moment, I've forgotten what this plant is, likes car parks, and it is very wee. Keyed it out, Common Whitlowgrass Erophila verna.

Drake Scaup and duck Ring-necked Duck from just off the sheep pens at Brodgar. Now, those will be interesting hybrids! The reason I headed out to Brodgar in the first place.