A Morphological Case Study of a Potential Hybrid Sea Turtle Between the Green Turtle (Chelonia mydas) and the Loggerhead Turtle (Caretta caretta) on the Shores of Farwa Island, Zuwara, Libya

Abstract

Marine turtles are highly endangered key bio-indicators in the Mediterranean basin, making the documentation of their rare phenotypic anomalies essential for understanding population dynamics. This study presents a descriptive morphological assessment of a juvenile sea turtle encountered during a routine field survey on the shores of Farwa Island in Zuwara, Northwest Libya. Preliminary physical evaluations revealed an overlapping mosaic of diagnostic traits split between the Green sea turtle (Chelonia mydas) and the Loggerhead sea turtle (Caretta caretta). The specimen exhibited a Curved Carapace Length (CCL) of approximately 40–45 cm, placing its estimated developmental age between 5 to 10 years. Key intermediate morphological characteristics were recorded, including a transitional head volume, hybrid lower and upper jaw structures, and structural variance in the carapace's peripheral scutes and coloration. These visual data strongly indicate a potential natural hybridization event between the two sympatric species. Due to localized logistical and infrastructure limitations, molecular verification (such as mtDNA or nuclear DNA analysis) could not be executed. This paper discusses potential environmental drivers for this phenomenon, including climate change impacts on migratory routes and nesting site overlaps, and stresses the urgent need for non-invasive long-term monitoring networks along the Libyan coast to safeguard these vulnerable marine populations.