Lindsey Buckingham, lead guitarist and a key songwriter for Fleetwood Mac for more than half of its existence, is again leaving the group, this time just two months before its new tour, the band said in a brief statement Monday.

"Lindsey Buckingham will not be performing with the band on this tour," the statement said. "The band wishes Lindsey all the best."

The immediate fate of the tour wasn't known Monday night. The band's website substituted an art illustration from one of its albums for its group photo, and a link to the planned tour returned a dead page.

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Rolling Stone and Variety, without naming their sources, reported that Buckingham had been fired — a not-implausible development in light of the band's tumultuous 50-year history. Buckingham himself left the band in 1987 and stayed away for almost a decade, returning only to play at Bill Clinton's presidential inauguration in 1992.

As news of the breakup spread, Mick Fleetwood, a co-founder of the original band in 1967, said in a statement that Mike Campbell of Tom Petty and the Heartbreakers and Neil Finn of Crowded House would replace Buckingham on the planned June tour, specific dates for which haven't been announced.

The split revived a debate that has surrounded the band since 1975, when Buckingham and Stevie Nicks, his girlfriend at the time (and later his wife and then his ex-wife), joined Fleetwood and two other existing members, John McVie and Christine McVie — what is the real Fleetwood Mac, anyway?

When it started in 1967, Fleetwood Mac was a British blues band formed by former members of John Mayall's Bluesbreakers, the British rotating collective that gave a host of music superstars their big breaks, among them Fleetwood; John McVie; Eric Clapton and Jack Bruce of Cream; Mick Taylor, a guitarist for the Rolling Stones during some of their most creative years; Aynsley Dunbar of Frank Zappa's Mothers of Invention; Andy Fraser of Free; and Rick Vito, a longtime collaborator of Bob Seger's.

In 1975, Buckingham and Nicks, who'd been a moderately successful folk-rock duet, joined up — radically transforming the band's sound from blues-based rock to Beach Boys- and Phil Spector-inflected FM album rock and helping to produce such landmark albums as "Fleetwood Mac" in 1975 (the band's second with that title), "Rumours" in 1977 and "Tusk" in 1979.

Both variants of the band have their devotees, although the Buckingham-Nicks iteration sold millions more records. When Fleetwood Mac was inducted into the Rock 'n' Roll Hall of Fame in 1998, members of both versions went in with it, notably co-founder Peter Green.

Reaction to the latest breakup brought out both camps, with many fans saying Fleetwood Mac was dead and others suggesting that Campbell and Finn could help the band return to its roots.

For all you so called fleetwood mac fans all up in arms about lindsey buckingham. He is a great guitarist and songwriter. No doubt about it. But to suggest the band is nothing without him is stupid. Get real seriously. — Chuck Roast (@roast_chuck) April 10, 2018

#LindseyBuckingham is a truly superb musician and the heart of the sound that made @fleetwoodmac commercially and internationally successful.



But to say the band can’t exist without him denies history, and ignores the genius that is Peter Green.#ohwell — Mark Thomas (@Informalytics) April 10, 2018

Fleetwood Mac has a rich, rich history. Let's not pigeon hole it to 12 years out of 40+... — Goo T. Gwaba (@GooGwaba) April 10, 2018

The Neil Finn joins Fleetwood Mac moment has freaked a few out but loads of people are stoked for Neil. I like that his musical road isn't predictably straight- a good detour! pic.twitter.com/UVjWjQtxei — Gryphon Music (@GryphonMusic) April 10, 2018

#FleetwoodMac was Fleetwood Mac even before Stevie. They’ve had several line ups, yes? I love the current (well, now not so current) FM, and am grateful to have seen them live, all five together just a few yrs back... Lindsey leaving does seem odd for a “farewell tour,” right? 🤔 — Cassandra Elizabeth (@BodlakAiflex) April 10, 2018