I collected this bee, a male, from Sallow blossom at Hartlebury Common on 17th April 2008. I believe this is the first record of this RDB species from Worcestershire. M.E.Archer has afforded it a national status of very rare. Geoff Trevis has agreed with my identification.
N.signata is a cleptoparasite of Andrena fulva (Muller in Allioni, 1766), the ‘Tawny Mining Bee’. Many readers will be familiar with A.fulva due to the combination of its bright orange-red furry appearance, its relative abundance and the fact that it commonly excavates its nest burrow in garden lawns during Spring. Therefore it seems rather strange that N. signata is such a rarity. The latest distribution map in the Provisional Atlas of the Aculeate Hymenoptera of Britain and Ireland (part 5) shows a thin scattering of records across southern England and Wales, a couple of records appear to be for Staffordshire and/or Shropshire? N.signata very much resembles its common relatives Nomada flava (Panzer, 1798) and Nomada panzeri (Lepeletier, 1841), it is possible that as a result it may have been overlooked in the past. N.signata should be looked for during April & May at sites similar to Hartlebury Common.
I was fortunate to photograph this one on Sallow blossom just prior to taking the decision to collect it, had I known it was possibly such a rarity I might not have risked the photo!
EDWARDS, R. & BROAD, G.R. 2005 Provisional Atlas of the Aculeate Hymenoptera of Britain and Ireland. Part 5. BWARS.
With thanks to Geoff Trevis for his expertise.