Aspects of the systematics of the viviparous bythitids, of the genera Ogilbia and Gunterichthys (Ophidiformes: bythitidae) in the Gulf of Mexico and Caribbean Sea

Abstract

Bythitidae are one of two viviparous families of the order Ophidiformes, a diverse but poorly known taxon of fishes that dominate large areas of the deep sea floor but that also live in the pelagic realm, on the continental shelf, on tropical reefs, in estuaries and in fresh waters. The bythitids comprise about 90 species in 31 genera and range from fresh waters to abyssal depths. Two of the several genera within Bythitidae, Ogilbia and Gunterichthys were the subject of this study. The primary objective was to investigate the morphological diversity of, the genus Ogilbia in the tropical Western Atlantic. Ogilbia specimens from the Gulf of Mexico and Caribbean Sea were compared to specimens of Ogilbia from the type locality of Ogilbia cayorum to elucidate the species diversity of the genus. The secondary objective was to compare Ogilbia specimens with specimens of Gunterichthys to test the validity of the monotypic genus Gunterichthys. This was accomplished by comparing the morphological characters of 0. cayorum and Gunterichthys longipenis. Morphometric, meristic and descriptive data were collected on all specimens. Raw data were analyzed using various statistical tests including Principal Component Analysis (PCA), Analysis of Variance (ANOVA) and the Tukey-Kramer multiple comparison test. Results from the analysis of morphometric, meristic and descriptive variables of 0. cayorum from the Gulf of Mexico and Caribbean Sea failed to support the hypothesis that Ogilbia is composed of several undescribed species found throughout the tropical Western Atlantic. Due to the subtle nature of the variation among specimens, 0. cayorum is considered a polymorphic species composed of three populations, an island population, a northern coastal population and a southern coastal population. Results of the present study confirmed the validity of the genus Gunterichthys. Based on morphometric, meristic and descriptive data analysis, 0. cayorum and G. longipenis are thoroughly dissimilar in all but minute characteristics.