Low levels of genetic diversity in Crocodylus acutus in Oaxaca and Guerrero, Mexico, and molecular-morphological evidence of the presence of C. moreletii

• 73 individuals were collected from six populations in Oaxaca and Guerrero, Mexico.
• There are 5 haplotypes in all 73 individuals after analysis of mtDNA-control region.
• Two monophyletic lineages were recognized, one corresponding to C. acutus and other to C. moreletii.
• Nil genetic diversity were found in C. acutus and h high but π low in C. moreletii.

The genetic variation in C. acutus from the Pacific coast of Mexico was investigated using mitochondrial DNA data. Overall, the localities sampled included three in the State of Guerrero and three in the State of Oaxaca, Mexico. We inferred phylogenetic and genealogical relationships, and genetic diversity was determined, using partial sequences of the mitochondrial control region. Additional published sequences from GenBank for C. acutus and C. moreletii were utilized. The results obtained from 73 crocodile sequences indicate the presence of five haplotypes grouped into two monophyletic lineages, one corresponding to C. acutus and the other to C. moreletii. The presence of C. moreletii in Chacahua (Oaxaca) was unexpected. The level of nucleotide diversity was nil and moderate in C. acutus and C. moreletii lineages, respectively, consistent with other publications concerning Crocodylia. Further studies of crocodiles in Chacahua (Oaxaca) are necessary to assess the possibility of hybridization.