Form and function of labral fan-ray microtrichia and posterior proleg barbs in Neotropical black flies larvae (Diptera: Simuliidae)

The microtrichia of the labral fan primary rays, considered as the finest structure of the larval filter mechanism in Simuliidae, and the posterior proleg hooks, a structure used for substrate attachment, were describe using Scanning Electron Microscopy for the first time in 14 Neotropical species of black flies. Four patterns of primary rays microtrichia and two types of hooks barbs disposition were found. The present study provides new morphological information for Neotropical black fly species, compares it with previous information for worldwide species. Also, shows that the presence of posterior proleg hooks barbs is common among black fly species, that these barbs are not related with the larval habitat or with the primary ray microtrichia pattern, and that flow conditions may influence the last-instar larvae microtrichial patterns, at least in most of the Neotropical species studied here.

Automated summary

This study utilized scanning electron microscopy to describe the microtrichia of labral fan primary rays and the posterior proleg hooks in 14 Neotropical black fly species for the first time. It found four patterns of microtrichia and two types of hooks barbs disposition, suggesting that posterior proleg hooks barbs are common among black fly species and not related to larval habitat or microtrichial patterns. Additionally, it indicated that flow conditions may influence the microtrichial patterns of last-instar larvae in most Neotropical species studied.