DNA barcoding of Glossogobius species (Teleostei: Gobiidae) from major lakes in the Philippines reveals the presence of cryptic species and species complexes

Glossogobius is the most speciose among all the genera of the family Gobiidae. Eight species of Glossogobius have been reported in the Philippines, which include the most abundant and commercially important species, G. aureus. In this study, Glossogobius specimens were collected from nine lakes in the Philippines. A total of 113 specimens were DNA barcoded using the mitochondrial cytochrome c oxidase subunit I (COI) gene. Additional sequences of Glossogobius were mined from GenBank. The neighbor-joining (NJ) tree showed that all the specimens from Laguna de Bay, Naujan, Buluan, Bato, Buhi, and Paoay lakes clustered with G. aureus sequences from GenBank with a 99% bootstrap support. Ten of the 14 specimens from Taal Lake were also included in this cluster; the other four specimens morphologically identified as G. illimis formed a separate cluster. The specimens from Lake Lanao formed two separate groups: one group clustered with G. aureus, while the other group formed a separate cluster and were designated as G. cf. aureus because they are morphologically similar to G. aureus, but are genetically divergent from it. All the 20 specimens from Lake Mainit formed a separate cluster and are most likely a new and still undescribed species. DNA barcoding also lends support to previous studies which showed, based on morphological data, that G. giuris and G. celebius are species complexes. Within-species genetic distances suggest that G. callidus, G. bicirrhosus, and G. circumspectus are also species complexes. The discovery of possibly new species from Lake Mainit, cryptic species from Lake Lanao, and the presence of species complexes in Glossogobius have implications on the proper conservation and management of these important fishery resources.