Never heard of it? No, neither had I. It's a fly that leaves tell-tale mines on Stinking Hellebore leaves. I only know this because pan-listing professional (yes, another one) Graeme Lyons blogged about it last week. I went looking and found these - they seem to match up with photos on the web. I have no idea how common this species is, but the first group of plants I looked at all had these mines. I have recently seen plenty of signs from another Phtyomyza fly, this time on Holly. Thanks Graeme!