One Direction -- We're Still Talking to Zayn Malik ... But Planning for Foursome

Four is the magic number for One Direction, because the band has no plans to add a fifth member following the Earth-shattering departure of Zayn Malik.

Sources close to Simon Cowell and the record label tell TMZ ... the band is moving forward with recording their new album sans Malik. As for eventually finding a replacement -- we're told there's "absolutely zero" talk of that.

That being said ... we're told the remaining 1Ders are still talking to Zayn regularly, and the band completely respects his decision to bolt.

One Direction played its first Zayn-less show in South Africa earlier this week. They tour Europe in June before hitting the U.S. in July.