Understanding species diversity of the amphidromous Indopacific goby genus Stiphodon (Gobiidae: sicydiinae)
Gobies constitute a great majority of fishes seen in oceanic island fish communities. Of particular interest in these communities are the amphidromous gobies of the subfamily Sicydiinae. Adult gobies spawn upstream in freshwaters from which newly hatched larvae are washed downstream to the sea. These larvae spend anywhere between 91-265 days at sea before returning to freshwater streams. This marine pelagic larval phase is believed to be the main mechanism behind the spatial and temporal dispersal of these species. However, very little life history information is known about these gobies. Males of the genus Stiphodon are brightly colored, but females are drab in coloration and pattern. Male coloration is the primary characteristic used to distinguish between these species, however, subtle differences in male coloration, overlapping distributions, as well as a lack of diagnostic morphological characteristics makes it difficult to distinguish species. Historically, most studies have been on identifying and describing species of Stiphodon by using morphological and pigmentary characteristics. More recently, molecular systematics and phylogenetic methods have been used to infer species delineations. This study is the most comprehensive phylogenetic analysis of this genus using three nuclear genes to determine species diversity and relationships among species. All nuclear phylogenetic trees support monophyly of the genus and recognize the presence of two clades, one more diverse than the other.