Absence of outer caudal setae on all larval instars of Phlebotomus tobbi from the Ionian Greek islands

Abstract

Larval instars 2, 3 and 4 of Phlebotomus tobbi Adler, Theodor and Lourie from the Greek islands of Corfu and Zakynothos were found to have two caudal setae instead of the four usually present on these instars of Phlebotomus larvae. In a scanning electron microscope comparison with larvae of P. papatasi (Scopoli), a sensillum was seen in place of each outer seta of P. tobbi larvae, suggesting secondary loss of the setae. As the larvae of less than a tenth of the species and subspecies of the genus Phlebotomus have been seen and described, it cannot be assumed that those of P. tobbi are unique in having only two caudal setae. However, four caudal setae in late instars can no longer be considered as a constant character of the genus Phlebotomus. Observations on the larvae of P. tobbi also raise the question of the unknown function of the caudal setae.