kleide fu'ivla

x1 is a clade/cladus/monophyletic class formed by most-recent common ancestor(s) x2 and all lineal descendants thereof in family/directed tree structure/according to relationship or standard x3.

x2 should technically be unique modulo considerations such as sex (both biological parents are the MRCA of biological full siblings, for example), but might typically be extended to a taxon which includes the true x2 in practice (and thus will slightly differ from the crown clade defined by that taxon, in that it could exclude the MRCA of the defining taxon). See also: "kraune", "klesi".