Mitochondrial DNA Analysis Reveals Two New Species within the Balistoides conspicillum Complex: Balistoides ampapagoticus sp. nov. and Balistoides pacificus sp. nov.

The clown triggerfish, Balistoides conspicillum (Bloch & Schneider, 1801), stands as one of the most iconic and thoroughly documented teleosts within marine ecosystems, possessing a historical distribution that extends from the Western Indian Ocean to the Philippines and Japan (Sahayak et al., 2014; Shimizu, 2021). As a representative of the family Balistidae, this predator fulfills a critical ecological role within its habitat; equipped with formidable jaws and a specialized palatine bone that maximizes upper jaw rotation, it belongs to the durophagous guild, specializing in the crushing of hard-shelled benthic organisms (Matsuura, 1979). Owing to its unmistakable coloration—distinguished by large pale spots on the ventral surface, a reticulated pattern on the dorsum, and vibrant markings on the snout—this fish has historically been classified as a monotypic taxon with a vast geographic range (Sahayak et al., 2014).For decades, the pronounced phenotypic conservatism associated with its chromatic pattern has prompted the scientific community to categorize most morphological deviations as mere intraspecific fluctuations within a single, contiguous population. Nevertheless, morphometric and osteological investigations conducted on specimens from geographically disparate regions—such as the Lakshadweep Islands in the Indian Ocean, and the Uwa Sea or Okinawa in the northwestern Pacific—have meticulously documented the existence of specific variations in body proportions and skeletal architecture (Sahayak et al., 2014; Matsuura, 1979; Shimizu, 2021). In light of these latent data within the literature, the historical monotypic paradigm of B. conspicillum necessitated a rigorous analytical revision.The advent of molecular taxonomy and DNA barcoding, predicated on the amplification of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene, presently provides the "gold standard" for unambiguously identifying animal species and detecting concealed taxonomic divergences (Fontanilla et al., 2014). By leveraging the diagnostic precision of this marker, coupled with data mining practices of public genetic profiles accessible via the GenBank database, researchers can transcend the limitations of purely visual taxonomy (Fontanilla et al., 2014). The present study aimed to investigate the genetic and taxonomic architecture of the B. conspicillum complex. Through a rigorous in silico approach, based on the alignment of genetic sequences strictly anchored to physically traceable, museum-deposited voucher specimens, this research seeks to map the evolutionary divergences within the taxon, formally testing the hypothesis that the clown triggerfish represents not a single biological entity, but rather a complex of distinct, phenotypically highly similar species.