Pond skater - Gerris lacustris

[NickU]

Can anyone confirm my ID of this Pond skater as Gerris lacustris?

On stream margin, Wiltshire, 14.4.10

Nick Upton - naturalist and photographer

[Matt Smith]

This is a nymph, so the adult characters used for ID have not fully developed - you would need some detailed close ups of the front tibia, sides of the thorax and underside of the abdomen to stand a chance of an ID with an adult. Best that can be said is Gerris sp.

[NickU]

Hi Matt

Many thanks for your feedback. I'm surprised you say that the first image was of a nymph as it appears to have full length wings reaching to the tip of the abdomen, and I assumed it was an overwintered adult.

Anyway, to aid ID I attach some images of (the same individual I think) taken from a different angle and some detailed crops of front legs, abdomen and thorax. If this can't be defined as G. lacustris, what other possibilities are there for a Wiltshire stream in April?

Nick

[Matt Smith]

Pehaps it is the angle at which the first photo is taken, but the individual looks to have a very short abdomen, not nearly long enough for an adult, so a quick glance at the shape said "nymph". A closer look shows it is indeed fully winged, but I still can't see any abdomen.

The second series of photos are looking pretty good for G.lacustris, but I'd still and to look under a scope to confirm.

Matt

[NickU]

Thanks again Matt, Sorry, no specimen to check, just the photos, and abdominal views are always going to be tricky in the field; I got as low as I could without dipping the camera in the river or falling in as it was! I guess it's a probable G. lacustris, unless there are other very similar species it might have been.
Nick