Nearly at the end of my field season so I should be able to reactivate my blog now. I’ve recently swapped my Panasonic Lumix FZ-38 superzoom camera for a FZ-48 so that I can fit it with a macro adapter. After some truly neanderthal attempts to use my new kit, I eventually sussed it out with help from Mark Skevington, so here are some of my ticks from the last fortnight.
In a 1972 paper on British ground beetles (Carabidae), Carl Lindroth predicted that Harpalus griseus could occur in Britain, perhaps as a migrant, but could be overlooked as a small Harpalus rufipes. And in July 1995, Lindroth’s prediction came true when a single specimen of Harpalus griseus was found at a moth trap in Wimbledon. And then in 2008, Marcel Ashby found three by pitfall trapping in an arable field margin on Croxton Hall Farm, Thetford. I was working nearby in 2009 so I spent quite a bit of time revisiting this field margin, as did Marcel, but despite finding a load of other interesting beetles, including Ophonus laticollis, Norfolk’s first Zabrus tenebrioides for over 100 years, and Norfolk’s second record of Xantholinus laevigatus, there was no further sign of Harpalus griseus. But this year James McGill decided to check it out again and found a single Harpalus griseus on the night of 20th August, the 5th British individual. On a fairly warm Thursday night, Dave Buckingham, Andy Schofield and I joined James to take another look. We did find another singleton Harpalus griseus but tragically it was dead.
The pronotal shape is a good character to separate from H. rufipes, which has slightly concave pronotal side-margins towards the base, and more distinct, less blunt, hind-angles. On the underside, the last three abdominal segments provide the clincher: whereas rufipes is punctate and pubescent at the sides but smooth and hairless in the middle, griseus has a stripe of pubescence down the middle only. Or to put it another way, it has a Brazilian.
I am pretty gutted to have only found one dead griseus on the night, despite collectively checking what must amount to well over 100 Harpalus rufipes. But at least we know that it has been established in that field for at least five years now.