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The two well-known monomial bases of the (classical) coinvariant ring, the Artin basis and the descent basis, are indexed by permutations and correspond to the statistics inv and maj respectively. Both bases give combinatorial explanations for the Hilbert series of the coinvariant ring, which is $[n]_q!$. 

We construct a basis of the Garsia-Procesi ring $R_\mu$, a quotient of the coinvariant ring, using the catabolizability type of standard Young tableaux and the charge statistic. This basis is  a subset of the descent basis and is compatible with the Hilbert series of $R_\mu$ in the same manner.  Our construction of the basis provides the first direct connection between the combinatorics of the basis with the combinatorial formula for the modified Hall-Littlewood polynomials $\tilde{H}_\mu[X;q]$, due to Lascoux. We use this description to give an elementary proof of the fact that the graded Frobenius character of $R_{\mu}$ is given by $\tilde{H}_\mu[X;q]$.