The British species of Oedemera Olivier, 1789
Oncomera Stephens, formerly regarded as a distinct genus eg Fowler , Buck , Joy, is now included as a subgenus of Oedemera, this subgenus includes the single British species, Oedemera (Oncomera) femoralis (Olivier, 1803), and brings the total number of British Oedemera, including Oedemera s.str, to four. Among the British fauna our species of Oedemera are distinguished by:
5-5-4 tarsal formula. Size ≥ 5mm. Second antennal segment short; half to one sixth as long as third. Terminal segment of maxillary palps slender, almost cylindrical and appearing obliquely truncate. Antennae 11 segmented in both sexes, filiform, all segments elongate, last segment not disproportionally longer than the others. Head across eyes at least as broad as, and usually broader than pronotum. Pronotum obviously narrower than elytra, constricted behind middle and with obvious anterolateral depressions. Elytra with (sometimes very fine) raised longitudinal lines, the innermost extending to about one third from base. Protibiae with two terminal spines.
Our two subgenera are distinguished thus:
Eyes large and weakly emarginate, interocular distance less than or equal to distance between antennal bases. Elytra with a raised transverse line between the first (abbreviated) and second longitudinal lines.	Oedemera (Oncomera)
Eyes smaller, not emarginate although may be weakly sinuate in outline, interocular distance more than distance between antennal bases. Eltra without raised transverse line.	Oedemera s.str.
Oedemera femoralis (Olivier) is a local insect of England and Wales north to Lancashire and Westmoreland (Buck, 1954). The species is nocturnal, frequenting Ivy and Sallow from April to September (Joy) and sometimes coming to sugar (Fowler). 13-20mm. Elytra extremely long, disproportionally so. Testaceous to brown with darker areas to frons, lateral surface of pronotum, legs and abdomen. Female abdomen entirely testaceous. Male metafemora dilated and metatibiae armed. Oedemera s.str. Our three British species may be separated as follows. Oedemera nobilis (Scopoli) is generally larger, 8-10mm, with brilliant metallic green or blue colouration which often has distinct red overtones. The elytra taper towards the apex; compare the width of an elytron below the shoulder with the width about 1/5 from apex. Male metafemora strongly dilated, pubescence on metatibiae long and erect. Oedemera lurida (Marsham) and Oedemera virescens (Linnaeus) are generally smaller than O.nobilis and are a dull sage green in colour. In both species the elytra are only slightly narrowed, towards the apex at least three quarters of the width at the shoulder. Males have been separated eg Fowler, Joy, Buck, on the hind femora which are very obviously dilated in virescens but only very slightly so in lurida. The aedeagi are distinct; in lurida there is a prominent tooth on the dorsal surface before a slightly dilated and rounded apex. In virescens the aedeagus tapers to a blunt apex and there is a small subapical hook which does not protrude above the dorsal margin. Females of these two species have been separated on size (or by association), Buck gives 8-11mm for virescens and 5-7.5mm for lurida, while Joy gives 7-9mm and 5-7mm respectively. Vazquez-Albalate (2003), however, gives 6.5-11mm for virescens and 5-8mm for lurida which would seem to invalidate previous British keys. Vazquez-Albalate does, however, provide a definite character for separating these females; in virescens the last abdominal sternite is broadly emarginate apically while in livida it is rounded. These must be looked at very carefully as in set specimens these relatively soft structures may be deformed and their appearance confused against the overlying tergite which, in both species is emarginate. To fully appreciate this feature the last abdominal segment (or the apical half, or even the whole abdomen, which is easier) should be removed, softened in warm KOH for a few minutes, and cut along one side so that the plates can be laid flat and viewed independentally, they may then be washed (with a little dilute organic acid) and mounted with the specimen using a tiny spot of gum. Reference Vazquez-Albalate, X. European fauna of Oedemeridae, Argania, 2003