Morphological characterization of genital structures and sexual dimorphism in Cephalopina titillator (Diptera:...

Sexual dimorphism is widespread among insects and is evident in the variations in external morphology and genital structures that are significant for species identification and reproductive behavior. This study provides the first detailed morphological description of the male and female genitalia of the camel nasal botfly Cephalopina titillator (Clark, 1816) (Diptera: Oestridae), together with an ecological niche modeling assessment of its potential distribution under both current and future climate scenarios. Adult specimens were reared from larvae collected from infested camel heads (Camelus dromedarius) at El-Bassatin abattoir, Egypt, between July 2023 and November 2024. Male genitalia are characterized by a helmet-shaped epandrium, Y-shaped cerci bearing marginal spines, massive surstyli, and a fan-shaped ejaculatory apodeme with paired multidentate lateral sclerotizations. Female genitalia exhibit a triangular epiproct, a rounded hypoproct, a W-shaped vaginal plate, and three distinct spermathecae of varying shapes. The present study highlighted the important role of the differences in forewing venation, scutal markings, and texture of abdominal sternites in easily and quickly distinguishing between both sexes of C. titillator. Ecological niche modeling using the MaxEnt algorithm and six uncorrelated bioclimatic variables revealed that precipitation of the wettest month (Bio13) was the strongest predictor with over 40% contribution to model performance. Strong predictive accuracy of the model was reported by AUC = 0.88; TSS = 0.7, which indicated that C. titillator is most frequently found in arid and semi-arid regions of North Africa, the Middle East, and the Horn of Africa. Future projections under the SSP5-8.5 scenario reveal that the species is going to continue and expand its range, particularly across the Sahel and East Africa, with contractions in the northern latitudes. Such outcomes are essential taxonomic characters for accurate identification and add to our understanding of the ecological and climatic determinants governing the distribution of this economically relevant parasite of camels.