The present study reports the new records of two species of the hippolytid shrimp genus Lysmata Risso, 1816 in the water off Lakshadweep Islands, India from the Arabian Sea, viz. Lysmata hochi Baeza & Anker, 2008 and Lysmata amboinensis (De Man, 1888) with more taxonomic information. Moreover, L. hochi is the first distributional report from the Indian Ocean. It is morphologically similar to L. kuekenthali and differences are discussed. Colour pattern and morphological trait of L. amboinensis are very close to L. grabhami which also differs in the presence of anti-penultimate segment of 3rd maxilliped more than 2.0 times as long as penultimate segment and stylocerite does not reaching the distal end of the cornea. These specimens were obtained at a depth of 0.5-2 m from the intertidal region of Agatti Island. Additionally, we estimated pairwise genetic distances for these two species and congeneric species using cytochrome oxidase subunit I gene sequences where interspecific distances ranged from 11-25.8 %.
The present study reports the new record of Thor hainanensis Xu & Li, 2014, on the basis of material from Agatti Islands in the Lakshadweep, India. This species was recently described from Hainan Island, China. Relationship of this species to two closely related species (T. paschalis and T. amboinensis) is discussed in this manuscript. Similarly, the present study also reports the rediscovery of other species, Lysmata ternatensis De Man, 1902 from the Lakshadweep waters with detailed taxonomic description. The present specimens were found to occur in the intertidal region in small crevices and rocks at a depth of 0.5-2.0 m. Genetic analysis using the mitochondrial COI sequences for both the species reveals close agreement for the morphological identification and showed the significant variation from the closely related species.
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.
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