[2] A distinctive trait of X. signum is the elongate black spot at the base of the caudal fin, which appears in both sexes when they reach the length of 1 cm and becomes obscured in adult males as their "sword" grows.

[1][4] X. signum is known exclusively from the drainage basin of Rio Chajmaic, a tributary of the Pasión River.

[1] There it inhabits pools and a small creek of fast, clear water shaded by a dense forest cover.

[2] The IUCN classifies X. signum as a vulnerable species due to its extremely limited range.

Small-scale agriculture exists throughout this range, but the major threat is the development of palm oil plantations.