Taxonomics studies of the Microculex subgenus (Diptera: Culicidae) occuring in Brazil

Author(s)

Rafael de Oliveira Christe

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Faculdade de Medicina (FM/SBD)
• Defense date: 2022-06-10

Examining board members

Mauro Toledo Marrelli; Juliana Telles de Deus; Karin Kirchgatter; Maria Anice Mureb Sallum

• Advisor: Mauro Toledo Marrelli

Abstract

The subgenus Microculex of Culex (Diptera: Culicidae) are a mosquitoes group composed for species almost exclusively associated with bromeliads as their main breeding sites. In recent decades, the presence and disorderly increase of human occupation in wild and environmental protection areas is remarkable. As this invasion process progresses, humans come into contact with organisms that were previously restricted to the wild. Although no species in this subgenus are incriminated as etiological agents vector for humans, its role in the maintenance of enzootic cycles is completely unknown and studies dealing with its taxonomy and ecological aspects have lack of information. Based on these premises, the aim of this work was to verify the validity of the wing geometric morphometric morphometry technique in the identification of Microculex species; to evaluate the existence of a pattern of dispersion of mosquitoes of this subgenus in gradients of vegetation cover and to propose a new dichotomous key of male genitalia. The geometric wing morphometric proved to be effective in species distinguishing Culex (Microculex) imitator; Cx (Mcx.) worontzowi; Cx. (Mcx.) pleuristriatus, Cx. (Mcx.) albipes e Cx. (Mcx.) lanei. The results are based on the use of 18 anatomical landmarks of wings through the MorphoJ 1.02 Software, where the Canonical Variable Analysis (CVA) an the reclassification test were indicated to determine the pattern of the wing shape of each species. The variation in Mahalanobis Distances was 4.404 6.3171, with statistical significance (p<0.001). Centroid-Size was measured using multivariated regression (10,000 randomizations) with statistical significance (p<0.0001). The patter of Microculex dispersion in gradients vegetation cover was evaluated using the Sorensen Index. Mean larval abundance and larval density were used as response variables. Mixed-Effect Models were used from the sample pseudo-replicates. The vegetation cover values of collection sites (60%, 70% and 90%) were adopted as Fixed Effects. The results appointed to Cx. (Mcx.) imitator was the most abundant species, while the species belonging to the Series Pleuristriatus are the best adapted to artificial breeding sites, and there is probably an evolutionary- adaptive process in these species. The morphological study of male genitalia has demonstrated progress in the taxonomic research of Microculex, managing to expose the 11 importance of correct dissection and observation of morphological structures previously little explored, such as aedeagus sclerite (AeS) and lateral plate (PL). Through technical illustrations, it was possible to redescribe the genitalia of 23 species and organize a new illustrated dichotomous key. Due to degree of variation found, the existence of a species complex in Cx. (Mcx.) neglectus, making up the Neglectus Complex. The distinction between the species Cx. pleuristriatus and Cx. albipes was suggested. The finding of species that do not correspond to the descriptions and orientations of the existing keys presupposes the unknown species existence (AU)

• FAPESP's process: 17/02342-7 - Systematics studies in Microculex genus of the Culex (Diptera: Culicidae)occurences in Brazil
• Grantee: Rafael de Oliveira Christe
• Support Opportunities: Scholarships in Brazil - Doctorate