For those who are interested, that is what I found when I opened the engine today:
Although the dealer said he has replaced the nut I found the OEM nut without the cuts in its edges. No Loctite.
And that'ts the nut I fitted with Loctite and torqued to 80NM
Blocking the gears between clutch and crank with a 5 Eurocent coin worked very well. The coin was bent afterwards :-)