Morphology of Larval Antennae and Mouthparts of Four Indian Sand Flies (Diptera: Psychodidae) by Scanning Electron Microscopy

The mouthparts and antennae of the fourth-instar larvae of four sand fly species were studied using scanning electron microscopy. The morphology of the clypeus, labrum, mandible, maxilla, mentum, and antennae were compared for Phlebotomus argentipes Annandale & Brunetti, P. papatasin (Scopoli), Sergentomyia babu babu (Annandale), and S. bailyi (Sinton). Most of structures exhibited species-specific features, particularly the characteristics of the antennae. P. papatasin larvae had heart-shaped antennae, a long mandible, stout maxilla, and a heavy mentum with large teeth. In contrast, P. argentipes larvae had dumbbell-shaped antennae and a singular club-shaped labrum. The antennae of S. b. babu were ovoid, whereas those of S. bailyi were elliptical. The labrum of S. b. babu was lanceolate, whereas that of S. bailyi was rounded and exhibited a small, thick projection with several folds. The teeth of the mentum of both Sergentomyia species were shorter than those of the Phlebotomus species. Species-specific differences in the morphology of larval mouthparts and antennae indicate that it may not always be necessary to rely on adult morphology to identify sympatric phlebotomines.