Estudo morfológico e morfométrico de citoformas de Simulium guianense Wise, s.l. 1911 (Diptera: Simuliidae)

Abstract

Simuliidae is a family of insects that shelter species of medical and veterinary importance due to the hematophagous habitus of females of most species, making them potential pathogen vectors for humans and other animals. The main disease associated with humans whose vectors are Simuliidae species is Onchocerciasis, with Simulium guianense Wise being one of the main vectors of the disease in the Amazonian focus of Brazil and Venezuela. Simulium guianense s.l. is a species complex consisting of 13 cytoforms, some of which could represent distinct species. However, to validate the existence of these species, it is necessary to find morphological or morphometric characters to distinguish and characterize them. Thus, the objectives of this study were: i) to evaluate if there are morphological differences between the analyzed cytoforms that can distinguish cryptic species in the Simulium guianense s.l. complex; ii), and to evaluate if geometric morphometry is a useful tool to distinguish cryptic diversity among the analyzed cytoforms of the Simulium guianense s.l. complex. The origin of the analyzed specimens is the same as that of 12 cytoforms of Simulium guianense s.l. complex already characterized in the literature, collected in Venezuela and Brazil. Morphological structures of taxonomic importance and the morphometry of larval postgenal cleft and pupal cephalic plate were used to compare the different cytoforms. The comparative study of the morphology of the selected structures did not showed consistent differences to identify cryptic diversity among the 12 cytoforms. Among these structures, the ventral plate of the male, one of the most informative structures for the taxonomy of many groups in Simuliidae, was in general uniform throughout the analyzed populations and the variations found were considered intraspecific. The morphometric-geometric analysis of the two selected structures was able to indicar some variations between the cytoforms, however, do not support the existence of cryptic species among the analyzed cytoforms. Further analysis, including other structures, may refine the analysis and provide nformation on the presence or absence of cryptic diversity. Thus, until new approaches are integrated to aid in the investigation of cryptic diversity in Simulium guianense s.l., none of the 12 cytoforms of this complex can be considered as species distinct from thenominal species.