An illustrated key to the cuckoo wasps (Hymenoptera, Chrysididae) of the Nordic and Baltic countries, with description of a new species Author Paukkunen, Juho Author Berg, Alexander Author Soon, Villu Author Odegaard, Frode Author Rosa, Paolo text ZooKeys 2015 548 1 116 http://dx.doi.org/10.3897/zookeys.548.6164 journal article http://dx.doi.org/10.3897/zookeys.548.6164 1313-2970-548-1 D5D7B51E5AC6460D9B3C7584E46F9B3F D5D7B51E5AC6460D9B3C7584E46F9B3F Taxon classification Animalia Hymenoptera Chrysididae Hedychridium caputaureum Trautmann & Trautmann, 1919 Hedychridium roseum var. caputaureum Trautmann & Trautmann, 1919: 35. Hedychridium chloropygum ssp. spatium Linsenmaier, 1959: 59. Hedychridium caputaureum : Niehuis 2001 : 121. Hedychridium chloropygum of authors, not du Buysson, 1888. Diagnosis. Length 5-7 mm. Together with Hedychridium roseum this species is easily differentiated from other species of the genus by its non-metallic red or orange metasoma. The head and mesosoma are mainly green or blue, but as opposed to Hedychridium roseum , the vertex, pronotum and lateral fields of the mesoscutum have coppery red colour or reflections. This coppery colour is sometimes only weakly visible. The metasoma often has weak purple reflections posteriorly. Especially in the males, the punctation of T3 and T2 is usually coarser compared to Hedychridium roseum . Distribution. Estonia, Finland, Latvia, Lithuania, Sweden. Rare. - West Palearctic: Europe and western Asia ( Linsenmaier 1997 ). Biology. Habitat: sparsely vegetated sandy areas, dry meadows. Adults visit flowers of Apiaceae ( Kusdas and Turner 1955 ). Flight period: mid-June to late August. Host: Astata minor (Kohl) ( Crabronidae ) ( Linsenmaier 1968 , Saure 1998 , our own obs.). Remarks. Hedychridium caputaureum was recently considered to be a central and northern European subspecies of Hedychridium chloropygum ( Arens 2010 ). However, as these taxa are both well characterised and have partially overlapping distribution areas, we treat them as separate species following Paukkunen et al. (2014) .