Hidden diversity in sardines: Genetic and morphological evidence for cryptic species in the goldstripe sardinella, <i>Sardinella gibbosa</i> (Bleeker, 1849)

Abstract

Cryptic species continue to be uncovered in many fish taxa, posing challenges for fisheries conservation and management. In <i>Sardinella gibbosa</i>, previous investigations revealed subtle intra-species variations, resulting in numerous synonyms and a controversial taxonomy for this sardine. Here, we tested for cryptic diversity within <i>S. gibbosa</i> using genetic data from two mitochondrial and one nuclear gene regions of 248 individuals of <i>S. gibbosa</i>, collected from eight locations across the Philippine archipelago. Deep genetic divergence and subsequent clustering was consistent across both mitochondrial and nuclear markers. Clade distribution is geographically limited: Clade 1 is widely distributed in the central Philippines, while Clade 2 is limited to the northernmost sampling site. In addition, morphometric analyses revealed a unique head shape that characterized each genetic clade. Hence, both genetic and morphological evidence strongly suggests a hidden diversity within this common and commercially-important sardine.