It's been too long since I last added anything to this blog, so it is a shame that I write this in the middle of fixing a(nother) mistake. I originally thought this specimen was Temnothorax nylanderi, collected well outside of its known range, and had started to pursue this, involving other people.
Instead it is Temnothorax saxonicus and I'm feeling quite sheepish. What's especially silly is that I collected T. saxonicus again just down the road from this specimen and had no problem with the identification.
I had taken these photographs and was sorting them out when I realised that the head was the wrong shape for T. nylanderi. On checking my measurements I discovered that I had originally incorrectly measured the head width. Thus, instead of the head length being less than 1.090 times the head width, the head was longer, which clearly made this T. saxonicus.
T. saxonicus is a rarity in Germany and is listed as 'highly endangered' (RLD2). The only place I collected it was just west of Poikham, Bavaria, though there is a slim chance that I may have other specimens unidentified. Seifert has told me that he expects this species in any comparable habitat along the river Donau (Danube).