Ericsson, who had not scored a point this season until taking the four for pole position - his first-ever in the series - left it late to grab the top spot, having previously led the way for much of the session only for Richelmi to look like he had snatched it late on.
Track conditions were dry but with cloud cover rolling in, and rain threatening, there was a clamour to get on track and set a time as soon as possible, with all cars qualifying on the soft-compound Pirelli control tyre.
Points leader Stefano Coletti (Rapax) was the first frontrunner to set a competitive time, but he was soon beaten by the following James Calado in his ART machine.
Ericsson then crossed the line to wrest the top spot away, with Sam Bird popping up in second moments later for Russian Time.
Carlin's Felipe Nasr then claimed the second spot, 0.057 seconds down on Ericsson's fastest time, demoting Bird to the second row alongside Calado.
On the second run on fresh tyres, as the rain held off, Coletti soon jumped to third, with only a scrappy few final corners costing him a spot on the front row.
With 10 minutes remaining, and the track temperature dropping a couple of degrees due to the cloud cover, Nasr was next to shoot at Ericsson's pole time. But his 1m29.168s was a fraction slower than he had managed on his first run, as again the final sector proved his undoing.
Bird then took a shot, but his final sector was half a second slower than Ericsson's, and he stayed third. He got to within 0.036s of Nasr's third-placed time, however.
Then from out of nowhere came Richelmi, who appeared to make big suspension changes in his time in the pits as he was only ninth after his first run.
He suddenly leapt to the top of the times - only for team-mate Ericsson to take it back seconds later by 0.165s.
Behind the all-DAMS front row, Nasr will start third ahead of Bird and Coletti.
Two-time feature race winner Fabio Leimer will start sixth for Racing Engineering ahead of Calado, with Robin Frijns in eighth ahead of two Kevins, Ceccon and Giovesi.
- Sports & Recreation
- Stefano Coletti
- James Calado
- Felipe Nasr
- Sam Bird