A descent map for curves with totally degenerate semi-stable reduction

Let $K$ be a local field of residue characteristic $p$. Let $C$ be a curve over $K$ whose minimal proper regular model has totally degenerate semi-stable reduction. Under certain hypotheses, we compute the prime-to-$p$ rational torsion subgroup on the Jacobian of $C$. We also determine divisibility of line bundles on $C$, including rationality of theta characteristics and higher spin structures. These computations utilize arithmetic on the special fiber of $C$.The final publication is available through the Journal de Theorie des Nombres de Bordeaux  http://jtnb.cedram.org/jtnb-bin/item?id=JTNB_2013__25_1_211_0