Species-specific repeat units in the intergenic spacer of the ribosomal RNA cistron of Anopheles aquasalis Curry.

A genomic DNA library of Anopheles aquasalis Curry was screened for clones that hybridized more intensely to DNA from A. aquasalis than to DNA from A. benarrochi Gabaldon, Cova Garcia, and Lopez, A. konderi Galvao and Damasceno, A. nuneztovari Gabaldon cytotypes A, B, and C, A. oswaldoi (Peryassu), A. rangeli Gabaldon, Cova Garcia, and Lopez, or A. trinkae Faran. Two specific clones (2.5 kilobasepairs [kbp] and 3.0 kbp) from A. aquasalis were isolated. Both A. aquasalis-specific clones were from the intergenic spacer region of the ribosomal RNA (rRNA) cistron. Upon digestion with Rsa I, a 900-bp fragment from the clone AA-1 hybridized specifically to A. aquasalis DNA. Analysis of the DNA sequence of this fragment revealed four tandemly repeated 36-bp units. Three of these repeat units were identical, and the fourth was 94% identical to the others. The DNA sequence of a highly conserved region of these repeats was used to synthesize an oligonucleotide probe specific to A. aquasalis.

Genetic evidence for the existence of cryptic species in the Anopheles albitarsis complex in Brazil: allozymes and mitochondrial DNA restriction fragment length polymorphisms.

Allozyme and mitochondrial DNA (mtDNA) restriction studies were undertaken to determine the extent of genetic divergence among field populations of Anopheles albitarsis in Brazil. Two sympatric species, An. deaneorum and An. marajoara, were identified in collections from Costa Marques (CM), Rondonia. Genetic evidence includes (1) the presence of two types of individuals, each with diagnostic allelic clusters (for Had-1, Pgi-1, Pep-1, Mpi-1, and Idh-1), (2) a deficiency of heterozygotes, and (3) characteristic mtDNA haplotypes. In addition, two allopatric cryptic species of An. marajoara were identified, one from Iguape (An. marajoara form IG), Sao Paulo state, and the other from the Island of Marajo (An. marajoara form MA). Though form IG and form-MA resemble form CM in wing spot morphology, they differ from it in diagnostic allozymes and mtDNA haplotypes. An. marajoara form CM had a higher variability (mean heterozygosity, H = 0.22, and percentage of polymorphic loci, P = 66.7) than did form IG and form MA (H = 0.08 in both, and P = 25.0 and 33.3, respectively). Form MA and form IG are genetically more similar to each other than both are to form CM. Based on wing morphology, estimates of F statistics, and genetic similarities, we propose that An. albitarsis in Brazil is a species complex. It comprises at least two morphologically distinguishable species: (1) An. deaneorum (currently one taxon) and (2) the An. marajoara species complex, which further consists of at least three cryptic forms, marajoara form MA, marajoara form IG, and marajoara form CM.