Did the Gnostics have apostolic succession?

It is often claimed that the Gnostics had apostolic succession. In particular, Clement of Alexandria is often used to show that the Gnostics claimed apostolic succession. > Basilides, though he claims (as they boast) for his master, Glaucias, > the interpreter of Peter. Likewise they allege that Valentinus was a > hearer of Theudas. And he was the pupil of Paul. For Marcion, who > arose in the same age with them, lived as an old man with the > younger [heretics]. And after him Simon heard for a little the > preaching of Peter. (Source ) Is it true that the Gnostics had apostolic succession? And if so, what is so special about it if even the Gnostic had claim to it?