Morphometry and Morphology of the Body and External Genitalia of Triatoma dimidiata (Hemiptera: Reduviidae) Morphotypes

In Yucatán state, Mexico, Triatoma dimidiata (Latreille, 1811) is the primary vector of Trypanosoma cruzi, the parasite that causes Chagas disease. The vector population presents diverse forms and colorations. Therefore, this study was designed to determine the morphotypes of T. dimidiata based on the taxonomy of the body and external genitalia. Between March 2023 and April 2025, 902 triatomines from 15 municipalities were examined. Three main morphotypes were characterized (I to III). Morphotype II was the most abundant (62.86%) and most distributed in the study area (12 of 15 municipalities), with a notable presence in forests and caves. Morphotypes I and III were found primarily outside houses and in chicken coops. Within the characterized specimens of T. dimidiata sensu lato, morphotype II displays more prominent morphological and structural characteristics. They are smaller compared to morphotypes I and III. In morphotype II, the spiracles are covered by a black spot that extends from the connexival plate to the urosternites. Males had short and robust parameres. The median process of the pygophore is long and slender compared to morphotypes I and III. The female tergite VIII has six sides. The taxonomy should be complemented by a study of the life cycle of each morphotype and analysis of its genome.