Round-backed Millipedes

Trigoniulidae

(after Hoffman 1994) The limitations of Pachybolidae, Trigoniulidae and Spiromimidae are poorly defined. All trigulionids have in common a spherical internal chamber in the coxa of the posterior gonopods. It receives a duct from a gland located dorsad to the gonopods in segment 7, and debouches into a so-called prostatic groove which follows a sinuous course out of the coxa and then fairly direct to the apex of the telopodite, sometimes ending in a cavity, sometimes on a small branch (solenomere).

Six general are currenly known in the Triguniolidae: Ainigmabolus, Austrostrophus, Leptogoniulus, Speleostrophus, Trigoniulus and Zygostrophus.