Phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) are small insects of major medical and veterinary significance, due to the bloodfeeding habits of the females. More than 1,000 species of phlebotomine sand flies have been described to date, many of which are recognized vectors of Leishmania spp. (Maroli et al. 2013). In the Americas, there are around 530 species and >20 species have been listed as vectors of Leishmania spp. to humans in this region (Maroli et al. 2013, Brazil et al. 2015, Shimabukuro et al. 2017).

Phlebotomine sand fly identification is mostly based on morphological features. Many species belonging to certain genera, or species groups, are morphologically similar, which in turn makes their identification a complex task (Galati 2018). In addition, misidentifications may result in wrong conclusions about the geographical distribution and even the vector role of a given species (Andrade Filho et al. 2004, Cutolo et al. 2009). Morphological anomalies have been documented in phlebotomine sand flies around the world (Kassem et al. 1988, Marcondes 1999, Florin et al. 2010). For instance, anomalies can occur in the antennae, palpomeres, male terminalia, and female spermathecae. These anomalies may eventually lead to misidentifications, including the wrong description of a new species (e.g., Mangabeira 1942). Nonetheless, the biological impact of such anomalies (e.g., on sexual behavior and reproduction) remains poorly understood. Considering the eminent taxonomic implications of morphological anomalies in phlebotomine sand flies, we describe herein a case of morphological anomaly in a male of Evandromyia lenti (Mangabeira).

This anomalous male was found during one of a series of phlebotomine sand fly collections conducted in Salgadinho Village, Pesqueira municipality (8°16.47′S, 36°40.2′W; 709 m above sea level), Pernambuco State, northeastern Brazil. The climate of Pesqueira is semiarid, with an average annual rainfall of 53.3 mm and an average annual temperature of 23.8°C (data obtained from Instituto de Tecnologia de Pernambuco meteorological station: 82890). The vegetation is predominantly composed of semideciduous and deciduous forests.

Sand fly collections were performed under the framework of different research projects in January 2017, July 2018, and January 2019. During 2 consecutive nights of each month, Centers for Disease Control and Prevention light traps (2 per night) were installed from 5:00 p.m. to 6:00 a.m., positioned 1.5 m above the ground in the peridomicile (chicken coop) of a house. The anomalous male and additional phlebotomine sand flies collected were identified morphologically and classified according to Galati (2018). The specimens were prepared as microscopy slides, and examined by light microscopy. The following structures were observed: first 3 flagellomeres, palps, labrum–epipharynx, clypeus, sperm pump (= ejaculatory pump), aedeagal ducts (= genital filaments), epandrial lobes (= lateral lobes), parameres, gonocoxites, and gonostyles were also analyzed. The anomalous male described herein is deposited (accession number: 91.623) in the collection of sand flies (FIOCRUZ-COLFLEB) of René Rachou Institute (Fiocruz), Minas Gerais, Brazil. We also compared the anomalous male to a normal male from Lassance, Minas Gerais, the type locality of E. lenti, which is deposited in the FIOCRUZ-COLFLEB collection (accession number: 81.272).

A total of 388 phlebotomine sand flies belonging to 4 species (i.e., Lutzomyia longipalpis (Lutz and Neiva), E. lenti, Nyssomyia intermedia (Lutz and Neiva), and Micropygomyia villelai (Mangabeira)) were identified. The predominant species was L. longipalpis (85.8%; 232 males and 101 females), followed by E. lenti (9.8%; 11 males and 27 females), N. intermedia (2.6%; 8 males and 2 females), and M. villelai (1.8%; 6 males and 1 female).

Among the 388 phlebotomine sand flies identified, we found the anomalous male of E. lenti. A careful examination of the terminalia of this male revealed an extra spine in both gonostyles. The gonostyle of the E. lenti male bears 4 spines (apical spine, upper external spine, lower external spine, and internal spine) and a spiniform preapical seta (Mangabeira 1938, Galati 2018). On the anomalous male, a 5th spine is present between the upper external spine and the lower external spine (Fig. 1). All other morphological features allowed us to unequivocally assign this male to the species E. lenti.

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Evandromyia lenti is a phlebotomine sand fly distributed in several Brazilian states, including Pernambuco (Dantas-Torres et al. 2010, Costa et al. 2013, Sales et al. 2019). This species has been found naturally infected by Psychodiella chagasi (Adler and Mayrink), a gregarine species also found in other sand fly species (Rocha et al. 2015). On the other hand, Brazil et al. (1997) carried out laboratory tests through experimental infections with E. lenti (from Minas Gerais State) with Leishmania amazonensis, but no evidence of infection was observed in 45 females of E. lenti dissected, strongly indicating that this phlebotomine sand fly is refractory to Leishmania amazonensis (Lainson and Shah) infection. Rêgo et al. (2015) found 2 E. lenti females (one collected in the peridomicile and other on a trail) positive for Leishmania infantum Nicolle DNA, suggesting that this phlebotomine sand fly could be involved in the transmission cycle of this parasite. However, experimental studies and more conclusive field data are needed to support this hypothesis.

Cases of anomalies have been described in other phlebotomine sand fly species in the Americas (Sherlock 1958, Marcondes 1999, Ximenes et al. 2002, Andrade Filho et al. 2004, Pinto et al. 2010, Sanguinette et al. 2013). From a broad perspective, the case of bilateral anomaly described herein is important for the taxonomy of American phlebotomine sand flies, since the occurrence of such anomalies can result in misidentifications in this important group of vectors.

Morphological anomalies in phlebotomine sand flies may be of genetic (embryonic/postembryonic) or environmental origin (Andrade Filho et al. 2004). The biological significance of such anomalies in phlebotomine sand flies is still unknown. However, from a taxonomic perspective, anomalous specimens may eventually be wrongly identified as a new species, as has happened in the past with Flebotomus nordestinus (Mangabeira) (Mangabeira 1942), which was later considered to be a junior synonym of Sciopemyia sordellii (Shannon and Del Ponte) (Young and Morales 1987). In this context, our report confirms that morphological anomalies may occur in E. lenti, which may help in preventing future misidentifications of this species.