Idiocnemis nigriventris

Male : Idiocnemis nigriventris is a dark member of the bidentata-group. The male has a yellow labrum with a dark basal mark, light brown anteclypeus, dark brown postclypeus, and a yellow-orange frons. The vertex is black with small brown-grey subtriangular postocellar spots attached to the eye margin. The synthorax has an interrupted antehumeral stripe, divided into an anterior stripe and a posterior elongate spot. The underside of the synthorax is entirely dark brown to black. The abdomen is mostly dark, with pale basal and subdistal markings on the middle segments and purple dorsal markings on segments 8–9. The most important diagnostic character is the male superior anal appendage, where the distal process is reduced to a small tubercle. Female : The female is similar to the male but generally paler. It can be recognized by the interrupted antehumeral stripe, entirely dark ventral side of the synthorax, and subtriangular postocellar spots attached to the eye margin. The abdominal segments show a sharp border between the pale subdistal markings and the dark distal rings. The cerci are black, which helps separate it from some related species in the bidentata-group.