This page represents the following TreeOfLife-200M taxonomic path.[1]
Acropsilus niger is a small fly, consistent with the general size range of the genus (1.0–2.3 mm) [2]. Observations of specimens indicate a slender body form typical of many dolichopodids [1]. The genus is characterized by an apical arista and a distinct transverse fold on the posterior mesonotum, just anterior to the scutellum [2].
The genus Acropsilus is well-defined by several diagnostic features. The clypeus in females and most males bears four projecting setae: a pair of shorter midcentral setae and a pair of stronger distal setae [2]. Acrostichal setae are absent [2]. In males, the first abdominal tergum is notably wider than the thorax and subsequent segments, and the hypopygium is pedunculate [2]. A key autapomorphy for the genus is the presence of an inverted Y-shaped carina on sternum 8 [2].
Acropsilus species are widely distributed in the Old World, showing high species richness in moist tropical habitats across the Afrotropical, Oriental, and Australasian regions [2]. They are frequently collected in malaise and water traps in tropical lowlands [2]. In northern Australia, populations are abundant during and after monsoonal rains, though they are restricted to permanent water sources during drier periods [2].