Compare the two Glocianus weevils in these images (click for large images). I didn’t think they could be the same species …
… and I thought my Sutton Bingham Reservoir specimen had to be something new to Britain. But they are both specimens of Glocianus punctiger. That is the opinion of Italian weevil expert Enzo Colonnelli, and there is nobody with greater experience of these species across Europe.
I haven’t found Glocianus weevils very often, though more so in recent years as I’ve started to use my suction sampler more and more routinely. To date I have recorded Glocianus distinctus on 5 occasions (6 individuals), G. punctiger on 4 occasions (4 individuals) and have not yet found the other two British species: G. moelleri and G. pilosellus. I’ve been keying them out using Mike Morris’ RES Handbook (Morris, 2008) but also dissecting males as a matter of routine. The two males pictured here are the only two males of G. punctiger that I have found. I thought I’d been lucky and discovered a species new to Britain but actually I’d been unlucky and found a specimen with really unusual genitalia! Anyway, it seems worthwhile to bring this to other peoples’ attention, especially as this is an extreme degree of variation to find within one species. I will certainly be dissecting and retaining any other male punctiger I find, to learn more about the variability of aedeagal structure in British populations. And as Enzo has said: “variation is the engine of evolution”!
Glocianus punctiger feeds on dandelions Taraxacum, mainly the Section Ruderalia which is by far the commonest Section of this large genus, and mostly includes micro-species which are weeds of lowland areas. Although the host plants are widespread and abundant, the weevil is much more restricted, typically being found in grasslands, waste places, at the sides of roads and tracks, in woods and in open and rough ground generally (Morris, 2008). It occurs very locally throughout England and Wales and has Nationally Scarce (Nb) conservation status.
I am very grateful to Mike Morris for all his help in investigating the identity of the Sutton Bingham specimen and for putting me in touch with Enzo Colonnelli, to whom I am very grateful for letting me have his opinions on my photographs. As ever, I am indebted to James Hogan, Zoe Simmons and Darren Mann at the Hope Department of Entomology, Oxford University Museum of Natural History, for access to their digital auto-montage equipment. The atypical specimen from Sutton Bingham Reservoir was found during surveys of the invertebrates of unimproved grassland habitats for Wessex Water.
Morris, M.G. (2008). True weevils (part II) (Coleoptera: Curculionidae, Ceutorhynchinae). Handbooks for the identification of British insects, vol. 5, part 17c. St Albans: Royal Entomological Society.
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.