Philippine Science Letters
vol. 4 | no. 2 | 2011
published online December 9, 2011


DNA barcodes of the suckermouth sailfin catfish Pterygoplichthys (Siluriformes: Loricariidae) in the Marikina River system, Philippines: Molecular perspective of an invasive alien fish species

by Joycelyn C. Jumawan1,3*, Benjamin M. Vallejo2, Annabelle A. Herrera3,
Corazon C. Buerano3 and Ian Kendrich C. Fontanilla3

1Biology Department, CARAGA State University, 8600 Butuan City, Philippines
2Institute of Environmental Science and Meteorology, College of Science, University of the
Philippines, 1101 Diliman, Quezon City, Philippines
3Institute of Biology, College of Science, University of the Philippines, 1101 Diliman Quezon City, Philippines



DNA barcoding for accurate identification of invasive alien fish species is relatively unexplored. In this study, partial sequence (655 bp) of the mitochondrial gene COI (cytochrome c oxidase subunit I) was used to delineate between two species of exotic suckermouth sailfin catfish Pterygoplichthys - P. pardalis and P. disjunctivus and their intergrades, which dominate the ichthyofauna of the Marikina River system, Philippines. Individuals were assigned to groups using an abdominal pattern scheme, and COI gene sequence divergence analysis was determined using Kimura 2-parameter distances. Results revealed two major clusters which were inconsistent with the abdominal pattern categories and were characterized by low genetic divergence (mean 0.2%); one cluster having shared genealogy of individuals pre-identified as P. pardalis and the intergrades, and another consisting mostly of P. disjunctivus. From the samples, six haplotypes with low genetic divergence (mean 0.5%) were identified, suggesting that the haplotypes belong to a single species despite abdominal pattern variations. Overall, the DNA barcodes do not complement the morphology-based identification of the two species in the river system. The results support the possibility of introgressive hybridization between P. pardalis and P. disjunctivus and the need to reassess taxonomic assignment of the two species using abdominal patterns as basis for species distinction. It is recommended that multiple molecular tools be used in future studies and that native Pterygoplichthys species and other hypostomine loricariids be subjected to DNA barcoding to fully classify this genus that deserves taxonomic attention.

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Submitted: July 19, 2011
Revised: September 22, 2011
Accepted: September 29, 2011
Published: December 9, 2011
Editor-in-charge: Eduardo A. Padlan
Sevilla D. Detera-Wadleigh
Rachel Ravago-Gotanco