A fellow coleopterist recently said that Ousipalia caesula “has to be one of the most mysterious beetles on the British list!” I was intrigued, to say the least. So what’s the mystery? Well, there is not a single mention of it in 21 volumes of the journal The Coleopterist. There are only about 14 dots on the NBN Gateway map, and you have to take some of those with a pinch of salt. There’s no evidence that Derek Lott ever found it; in fact I only know one coleopterist who has …
Or should I say, “one other coleopterist”. I’ve just used the OUMNH collections to confirm that some small, blackish-brown aleocharine staphylinids that I collected at Sandwich Bay, East Kent on 3rd July 2012 are Ousipalia caesula.
It must be common here as I found 14 in a few minutes suction-sampling on the calcareous dune grassland just seaward of the road to the Prince’s Golf Club at TR360582. I was actually targeting Yarrow, as much as you can target one plant with a suction-sampler in such floristically diverse turf. The habitat fits with Marc Tronquet’s (2006) description for France: “on sandy ground, under lichens and in the flower spikes of Aira canescens“, except that Grey Hair-grass Corynephorus canescens (= Aira canescens) is absent from Kent and more prevalent on East Anglian dunes and a few spots in the Brecks (map here).
So Ousipalia caesula is probably no longer one of the most mysterious. We can’t say that it is a well understood species but it is only averagely mysterious: so many beetles are so poorly known! My guess with Ousipalia is that it is a habitat-specialist of dry, sandy ground with very short vegetation, good cover of bare ground, mosses and lichens, and perhaps favouring calcareous sites. It probably deserves to be regarded as Nationally Scarce, maybe even Red Data Book?
I would be interested to hear from anyone with more information on this beetle.
Thanks to James Hogan and Zoe Simmons at the Hope Department of Entomology, Oxford University Museum of Natural History for allowing me to take these montage photographs with their kit.
Tronquet, M. (2006). Catalogue iconographique des Coléoptères des Pyrénées-Orientales. Vol. 1: Staphylinidae. Supplément au Tome XV de la Revue de l’Association Roussillonnaise d’Entomologie. Perpignan: Association Roussillonnaise d’Entomologie.