Validation of the occurrence of the tropical eels, Anguilla bengalensis bengalensis and A. bicolor bicolor at Langkawi Island in Peninsular Malaysia, Malaysia

摘要

The anguillid eels found in Peninsular Malaysia were identified, using morphological analysis as Anguilla bengalensis bengalensis and A. bicolor bicolor and that identification was further validated by an analysis of the eels' mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16S rRNA) sequences. Previous studies had reported the occurrence of the tropical eel species A. marmorata in Peninsular Malaysia without validating the identification genetically, and after re-examination a number of key morphological characteristics of a preserved sample of A. marmorata, the sample from Peninsular Malaysia was identified as A. bengalensis bengalensis. This is the first record of the occurrence of A. bengalensis bengalensis in Malaysian waters that was confirmed by both morphological and molecular genetic analyses. Although one sample was identified as A. borneensis on key morphological characteristics, molecular genetic analyses showed that the sample was actually A. bicolor bicolor. These results indicate the difficulty of accurately identifying tropical eels solely on morphological analyses due to the sympatric distribution of a number of closely related eels.