Milonga — tango's quick, rustic cousin, in 2/4 and built on the habanera: a dotted eighth, a sixteenth, then two eighths (1, the a of 1, 2, the and of 2). The first three of those hits are the tresillo, which is why both cells are tagged; the fourth, on beat 2, is what makes it a habanera.
How it sits: the left hand plays the habanera as a rising arpeggio — low root, fifth in octaves on the sixteenth, then root and third — the shape Scivales uses for the habanera section of Sueño y Pasión; the bass doubles it. The right hand marks 1, the a of 1 and the and of 2 (the 3-3-2 half of the figure). The guitar plays the milonga campera strum: thumb on the bass note, then up-down-up chord strokes on the remaining three hits.
Listen for the sixteenth being late and light, almost a grace note into beat 2.
Practice: loop the clave layer and clap it, then play the left hand alone until the sixteenth stops rushing.