---

It is Sciapus heteropygus.
1st, abdomen colour is variable in this genus.
2nd, dark probably means reddish-yellow to brown-black.
3rd, alcohol lightens colour, sometimes strongly.
4th, I have checked original description:
Abdomen: les 4 premiers segments jaune rougeâtre, brillant, le segment 1 entièrement, 2, 3 et 4 avec bordure noire antérieure et postérieure, un léger reflet métallique
sur la ligne médiane; segment 5 jaune à l'extrême racine, 6 sur le quart apical, 7 entièrement.

Finally, I checked 14 males in my hands: most of them have darker abdomen, but 2-3 males have lighter segments, than your specimen.