Direct absorption and dispersed fluorescence (DF) spectra sample the (C2H2)-C-12 (X) over tilde(1) Sigma(g)(+) potential energy surface via profoundly different zero-order bright states. Despite the complementary nature of the data sets, a polyad model based on the approximate quantum numbers, N(x)v(1)+v(2)+v(3), N-r=5v(1)+3v(2)+5v(3)+v(4)+v(5), l=l(4)+l(5), accounts for the energies (+/-0.35 cm(-1)) and relative intensities for all transitions into pure bending levels (N-2=0) at E(vib)less than or equal to 12000 cm(-1) and N-r less than or equal to 15, l=0 and 2. The parameters that define this model are obtained by fitting 41 pure bending levels, of which 9 are J=0 energies derived from components of the [N-s=0, N-r=8, 10, 12, l=0, g] polyads observed in the DF spectrum. This polyad model provides a basis for extrapolating a description of otherwise indescribably complex spectra and dynamics to the E(vib)approximate to 16000 cm(-1) region of the barrier to acetylene <-> vinylidene isomerization, and could therefore provide a basis for detecting the pattern-breaking signature of the onset of isomerization.