Chaetotaxy of the fourth larval stage of Pintomyia longiflocosa, a primary vector of cutaneous leishmaniasis in Colombia.

Introduction: Pintomyia (Pifanomyia) longiflocosa is an endemic species from Colombia, found between the central and eastern Andes, and reported as one of the primary vectors of cutaneous leishmaniasis in coffee-growing zones of the country. This species is classified in the Townsendi series and can only be identified by the morphology of the male adults.
Objective: To determine the potential use of the fourth larval stage of the vector Pi. longiflocosa in morphological taxonomy based on the description of its chaetotaxy.
Materials and Methods: Pintomyia longiflocosa adults were captured in Campoalegre, Huila, and reared in the Entomology Laboratory at the Colombian Instituto Nacional de Salud. To identify the setae found in each corporal segment, 15 fourth-instar larvae were mounted on microscope slides using Canadian balm after being cleared with 10 % potassium hydroxide and saturated phenol. Additionally, five specimens were prepared for their observation by scanning electron microscopy.
Results: Based on the description of Pi. longiflocosa, we established that all species of the subgenus Pifanomyia so far described have the same antennal morphology and clavate setae along their body. However, various setae present in Pi. longiflocosa are absent in Pi. youngi, suggesting differences among the larvae of the Townsendi series.
Conclusions: These results support the potential importance of morphological characters from the fourth larval instar, such as antennal morphology and chaetotaxy, specifically in closely related species that are cryptic in their adult stages.