Netelia fuscicornis

I initially used Gavin Broad's key to nocturnal Ichneumonidae to identify this, but arrived at Netelia valvator. I looked into this and found that this was unlikely to be correct. At couplet 21 I had followed the option, "Forewing vein cu-a distal of Rs+M by 0.4 the length of cu-a or less; often without ocular-ocellar space" (as opposed to "about 0.7-1.0 the length" and "frequently with ocular-ocellar space". There was a very narrow ocular-ocellar space but the the ratio was around 0.45 so fitted clearly within the option I selected. Taking the other option would have led to fuscicornis. Eventually I found a draft update to the key which corrects the ratios - here the option leading to fuscicornis has a ratio 0.4-0.6 (vs. 0.3), so fine for my specimen. Initially I didn't think the genitalia were a good enough match for the diagram of fuscicornis, but I hadn't flattened it enough and when I looked again it was pretty close - some variation in the distal part but otherwise good and the closest match of any illustrated in the key.

male Netelia fuscicornis showing mandibles, claw, head, forewing (including close-up of vein cu-a in relation to Rs+M), scutellum, propodeum and genitalia, Wendling Beck Environment Project (Norfolk, UK), 9th August 2023

I had identified this species before, but apart from this set of photos I don't have any notes as to how it was identified. I'm sure I would have used Broad's key.

female Netelia fuscicornis showing forewing (inner and outer sections), back of head, scutellum and antennae, North Elmham Cathedral Meadows (Norfolk, UK), 8th September 2020

These two both keyed to fuscicornis although one on there was a small gap between the lateral ocellus and the eye while on the other there was no gap. There's usually an element of doubt so it was reassuring that the genitalia matched, but even that wasn't totally straightforward. The lateral lobe of the pad was large, as it should be, but the shape was less rounded than the diagram in Broad and on one of them in particular the shape of this lobe more closely resembled the diagram for dilatata. The key refers to the size of the lobe not the shape though, and other characters are, I think, sufficient to rule out dilatata.

male Netelia fuscicornis showing forewing veins cu-a and Rs+M, ocellar-ocular region, head from above, rear of abdomen and genitalia including two close-ups of pads, Wendling Beck Environment Project (Norfolk, UK), 6th September 2023

second male Netelia fuscicornis showing forewing veins cu-a and Rs+M, ocellar-ocular region, head from above, rear of abdomen and genitalia including close-up of pads, Wendling Beck Environment Project (Norfolk, UK), 6th September 2023

With a bit more experience under the belt now I keyed this to fuscicornis relatively straightforwardly. As usual the pads were hard to see, but I have discovered that they can be removed carefully so viewed apart from the ?paramere?. Still not easy to photograph as the edges are very membranous and transparent, but the shape was much easier to see under the microscope than when the pad was in situ. This one had 47 flagellomeres on each antenna.

male Netelia fuscicornis showing head from above (2 focuses), forewing and genitalia including isolated pad, Wendling Beck Environment Project (Norfolk, UK), 8th September 2023

This one was a female so I couldn't confirm it by checking the pads but having now had a few of these I'm reasonably confident. It had 45 flagellomeres on each antenna.

female Netelia fuscicornis showing head from above and wings, Wendling Beck Environment Project (Norfolk, UK), 11th September 2023