Bonefish leptocephali of the genus Albula are difficult to identify to the species level due to morphological similarities between two different species present in the Northeastern Pacific Ocean, A. esuncula and A. gilberti. In this study, 22 bonefish leptocephali (premetamorphic and early metamorphic), collected from two locations in the southern Gulf of California were identified as Albula gilberti by comparing 459 bp of their mitochondrial cytochrome b gene sequences to those of four other species of bonefish. The characteristics of these A. gilberti leptocephali were compared to those of previously described bonefish leptocephali in the region. No distinctive morphological characteristics (meristic and pigmentation) were found that differentiate premetamorphic leptocephali of A. gilberti from those of other Albula species, making species identification by molecular-genetics a necessity. In early metamorphic leptocephali some differences in horizontal eye diameter-head length ratio, number of rays of pelvic and anal fins and myomere of pelvic-fin origin may help to differentiate A. gilberti from A. esuncula.
Keywords: Albula gilberti; Gulf of California; cytochrome b; genetic identification; leptocephali.