Discovery of two new species of cobia (Pisces; Rachycentridae) inhabiting the makran coast of the northern Arabian Sea with notes on their biology and ecology

Abstract

Cobia, Rachycentron canadum has long been regarded as the sole species in the family Rachycentridae, and has a wide distribution in tropical and sub-tropical regions of the Atlantic, Indian Ocean and western Pacific. This study describes two newly identified species, Rachycentron blochii sp. nov. and Rachycentron makranesis sp. nov. from Gwadar in the northern Arabian Sea. The newly discovered species differ significantly from their relatives in multiple morphological traits, such as head profile, mouth, pectoral fin, caudal fin, caudal peduncle, dorsal and anal fin bases, gill rakers, and body coloration. Additionally, species delimitation was further supported by examining body scales and otoliths (sagitta, lapillus, and asteriscus), with shapes also delimiting species. The recent finding increases the number of cobia species in the northern Arabian Sea, Pakistan. Moreover, details on the biological and ecological aspects such as feeding habits, age assessment, habitat preferences and fishery-related details are presented.