Sexual and mating system in Thor hainanensis (Decapoda: Natantia: Thoridae) from the Lakshadweep Archipelago, India

Abstract

We tested the hypothesis that the Hainan’s squat shrimp Thor hainanensisXu & Li, 2014 undergoes a sex change and displays protandric hermaphroditism, a well-known feature from other congeners (T. dicaprioAnker & Baeza, 2021 and T. amboinensis (De Man, 1888)). We used morphological traits indicative of male function to categorize shrimp as prehensile males, non-prehensile males, and females. The linear relationship among the different morphological characters and the sexual morphs revealed that T. hainanensis has a sexual system of partial protandric hermaphroditism, where 50% of the population stays as active males and the rest of the population changes to female. Observations on the social and mating behaviour suggest that T. hainanensis exhibits a ‘search and defend’ mating system unlike other tropical caridean shrimps featuring protandrous hermaphroditism.