We consider the harmonic superspaces associated with SU(2, 2/N) superconfor
mal algebras. For arbitrary N, we show that massless representations, other
than the chiral ones, correspond to [N/2] 'elementary' ultrashort analytic
superfields whose first component is a scalar in the k antisymmetric irrep
of SU(N) (k = 1...[N/2]) with top spin J(top) = (N/2 - k/2, 0). For N = 2n
, we analyze UIR's obtained by tensoring the self-conjugate ultrashort mult
iplet J(top) = (n/2, 0) and show that N - 1 different basic products give r
ise to all possible UIR's with residual shortening.