Identification of two cryptic species in the Anopheles (Cellia) annularis complex using ribosomal DNA PCR-RFLP

Abstract

Anopheles (Cellia) annularis Van der Wulp is a complex of two sibling species provisionally designated as species A and B and can only be differentiated on the basis of the paracentric inversion in the ovarian polytene chromosomes. To analyze the distribution of these two species and to develop a molecular method for the identification of these two cryptic species, we sequenced the ribosomal DNA internal transcribed spacer 2 (ITS2) and domain 3 (D3) of A. annularis specimens collected from Sonapur (Assam), Jabalpur (Madhya Pradesh), Ranchi (Jharkhand), and Ghaziabad (Uttar Pradesh). We did not find any sequence variation among the specimens collected from Assam, Madhya Pradesh, and Jharkhand states, whereas two types of sequences were obtained from the specimens collected from the state of Uttar Pradesh, which correspond to species A and B of the A. annularis complex. Species A was more prevalent among the all four regions studied. The ITS2 sequence of species A showed unique restriction sites for MvaI and Eco24I, while species B displayed HinfI and NruI sites. Similarly, the D3 sequence of species A showed unique restriction site for Alw26I, while species B showed a unique KpnI site. In this study, we report for the first time the development of ribosomal DNA polymerase chain reaction-restriction fragment length polymorphism methods for identifying these two cryptic species of the Annularis complex.