Who is the leader of the flying fish riders?

Duval leads the flying fish riders. In the chapter the subordinates address him as boss while he issues orders during the attack on the Thousand Sunny and refers to his group as the Makuro Gang. The riders operate from a fortified island hideout flying their flag and follow his commands to pursue the mermaid and the Straw Hats. Subordinates report directly to him about Camie's location and he reacts with authority by snarling instructions. The scene shows him riding at the front declaring the target and vowing revenge. No other character is shown giving orders or receiving the title of boss in these pages. The manga states the answer outright in these sources.