Morphological Description of the Immature Stages of Nyssomyia umbratilis (Ward & Frahia) (Diptera: Psychodidae: Phlebotominae), the Main Vector of Leishmania guyanensis Floch (Kinetoplastida: Trypanosomatidae) in the Brazilian Amazon Region

Abstract

Nyssomyia umbratilis (Ward & Frahia) is the main vector of Leishmania guyanensis in the Brazilian Amazon region, where it is widely distributed. Studies have hypothesized that this phlebotomine is part of a cryptic species complex, spatially delimited by the Amazonian river systems, and with different transmission potential of L. guyanensis. In the present study, the immature stages of N. umbratilis are described from laboratory-reared specimens originating from the states of Amazonas and Pará, Brazil. Based on scanning electron and optical microscopy examinations, fine morphological structures (eggshell, setae, and mouthparts of larvae and pupae) are presented. A new form of sandfly pupae sexing (non-invasive) is also provided. The correct identification of insect is extremely important for the epidemiology of certain diseases. However, only the morphological characters of adult can be insufficient to separate accurately the closely related species. It is expected that the present description may contribute to solve the taxonomic problem involving N. umbratilis.

Morphological aspects of immature stages ofMigonemyia migonei(Diptera: Psychodidae, Phlebotominae) an important vector of Leishmaniosis in South America by scanning electron microscopy

“…cruciata [15], Ny. umbratilis [16], and this characteristic is not determinant to phylogeny for Lutzomyiina. The absence of the 3P seta in Mg. migonei is probably an apomorpy in this species, at least in comparison to the others discussed here in this paper.…”

“…beltrani [8] and Ny. umbratilis [16] apparently they are not in evidence. The setae 5, absent, is present in most pupae described, except for Ny.…”

“…The chaetotaxy and morphological structures of Neotropical phlebotomine larvae have been discussed previously by several authors [4,7,8,12,[14][15][16]27,29,32,[34][35][36][37][38]. The general aspect of head, the position of the mouthparts a somewhat prognathous, the peculiar shape of the egg buster, similar to a "volcanic cone" [7], the body shape cylindric, and the types of the most part of the bristles observed in Mg.…”

“…We presented in this study the first images of the pupa emerging from the Y suture of the head, and subsequently, the pupa, by movements of contraction and inflation, ruptures the thorax in the middle of the dorsal part. There are only a few pupae from Neotropical sand fly species described in detail using 3D images of SEM, howver, all the head setae, small spines, and basiconics are homologous to other Neotropical pupae described [8,[13][14][15][16].…”

“…The use of scanning electron microscopy (SEM) has significant improved the characterization and descriptions of immature forms, and provided details of larval chaetotaxy [4,5]; ontogeny [6][7][8]; spiracles [9,10]; antennal, and mouthparts, such as the sensilla as well as caudal bristles [7,11,12]. Despite this, only a few articles have been carried out about the pupal morphology of New World phlebotomine sand flies [8,[13][14][15][16]. Therefore, the number of descriptions of immature forms of sand flies still remains scarce.…”