I take it that the provision that called for deducting from a bloc’s total any votes won by component parties that failed to reach 3% was not operative in the final version of the law. (This possibility was alluded to by Federico in the comments to an earlier post.) In fact, there are parties within each alliance with less than 3% of the vote but with seats.
In the Chamber, the center-left bloc of Prodi has 220 of its 340 seats held by L’Ulivo, and seven other parties having from 4 (Svp) to 41 (Rifondazione comunista) seats each. Svp had only 0.48% of the vote.
Five parties contributed votes to the left’s total share, but won no seats. The largest of these was the Partito Pansionati, with 0.88%. The total vote won by these unrepresented parties on the left was just 1.54%. I assume there is a districting arrangement that I had not previously been aware of, since some parties with representation are smaller than others without.
In the center-right bloc of Berlusconi, Forza Italia has 137 of the bloc’s 277 seats. Four other parties have from 4 (Christian Democrat) to 71 (Alleanze Nazionale) seats each. Seven parties have no seats and combined they had 1.6%.
In the Senate, where the 55% provision for the leading blocs applies not nationally (as it does in the Chamber), but within regional districts, the center-left squeaked by, 158 seats to 156. The Senate looks even more fragmented than the Chamber (presumably due to the regional districting).
Thanks to MW for the tip on the source.