Found a nice fat dor beetle yesterday around some deer dung. Trying to key through using the old RES key (Jessop 1986), and I'm sure it's either Geotrupes spiniger or stercorarius, but I'm completely stumped by the 'proximal transverse carina on posterior tibia'. The sketches in the key are not much help, an I can't find anything online that assists. Anyone got anything that shows this character? Also I found a comment on a website about lobed mandibles on G. spiniger but no mention in the key - is this a valid character?
Tue, 22/04/2014 - 16:35
#1
Geotrupidae - tibial carina
I'm sure you've already checked these pages, but just as a compare and contrast exercise check the mandible shapes on the first pic compared to the second. Then check the size, positioning and shape of the projections on the fore tibia first vs second pic. Also check the size and distribution of the pitting near the rear of the pronotum. All my books are elsewhere at the mo so can't offer any more than that right now! Hope it adds something? Geotrupes spiniger - http://www.thewcg.org.uk/geotrupidae/0224G.htm
Geotrupes stercorarius - http://www.thewcg.org.uk/geotrupidae/0223G.htm
See also Mike Hackston's key. John Walters has also done a nice guide to them, but it seems to be out of print and is the only one of his series of guides that isn't available to download.
Skev,
See Beetle News vol 2:2 for an ID guide to Geotrupidae, and vol 3:1 for a more detailed guide to the mandible characters of spiniger and stercorarius.
You can download all issues of Beetle News here:
http://www.amentsoc.org/publications/beetle-news/
Mark
Thanks for the pointers - will try the key you mention Martin and check the Beetle news archives.