A filter element comprising: - a filter medium having an axis and forming a channel extending substantially axially; - a first and a second end plates (25, 26), each end plate covering one axial end of the filter medium and being sealingly mounted on said axial end, the first end plate having an opening in fluid communication with the channel; whereby a liquid to be filtered can flow through the filter medium towards the channel and out of the filter element through the opening, or reversely, wherein the filter element further comprises: - a protrusion fixedly secured to the first end plate and extending outwardly from said first end plate, the protrusion being substantially tubular and having a through hole in fluid communication with the first end plate opening, the protrusion forming a female coupling piece of a male - female connector; - a locking member capable of releasably locking a male coupling piece of said male - female connector in the female coupling piece, characterized in that: - the locking member is a piece which is distinct from the female coupling piece and which is mounted in said female coupling piece; - the female coupling piece comprises two radial walls (104, 105) which are orthogonal to the axis of the female coupling piece through hole, and which are spaced apart along said axis, the outermost radial wall comprising at least one radial notch (103, 110) for receiving at least one rib (203, 203a, 203b) of the male coupling piece, at least a part of said radial wall located adjacent a notch (103, 110) forming an abutment for said at least one rib (203, 203a, 203b) to prevent axial movement of the male coupling piece out of the female coupling piece; - the locking member is mounted between said radial walls (104, 105); and - at least one radial cavity is provided in the female coupling piece, between said radial walls (104, 105), for receiving part of the locking member and allowing radial deformation of said locking member. - a filter medium having an axis and forming a channel extending substantially axially; - a first and a second end plates (25, 26), each end plate covering one axial end of the filter medium and being sealingly mounted on said axial end, the first end plate having an opening in fluid communication with the channel; - a protrusion fixedly secured to the first end plate and extending outwardly from said first end plate, the protrusion being substantially tubular and having a through hole in fluid communication with the first end plate opening, the protrusion forming a female coupling piece of a male - female connector; - a locking member capable of releasably locking a male coupling piece of said male - female connector in the female coupling piece, - the locking member is a piece which is distinct from the female coupling piece and which is mounted in said female coupling piece; - the female coupling piece comprises two radial walls (104, 105) which are orthogonal to the axis of the female coupling piece through hole, and which are spaced apart along said axis, the outermost radial wall comprising at least one radial notch (103, 110) for receiving at least one rib (203, 203a, 203b) of the male coupling piece, at least a part of said radial wall located adjacent a notch (103, 110) forming an abutment for said at least one rib (203, 203a, 203b) to prevent axial movement of the male coupling piece out of the female coupling piece; - the locking member is mounted between said radial walls (104, 105); and - at least one radial cavity is provided in the female coupling piece, between said radial walls (104, 105), for receiving part of the locking member and allowing radial deformation of said locking member.