  A $K_4$-curve is a smooth, proper curve X of genus 3 over a nonarchimedean
field whose Berkovich skeleton $\Gamma$ is a complete graph on 4 vertices. The
curve X has 28 effective theta characteristics, i.e. the 28 bitangents to a
canonical embedding, while $\Gamma$ has exactly seven tropical theta
characteristics, as shown by Zharkov. We prove that the 28 effective theta
characteristics of a $K_4$-curve specialize to the theta characteristics of its
minimal skeleton in seven groups of four.
