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.
A new species of the genus Urocaridella Borradaile, 1915, Urocaridella arabianensis n. sp. is described and illustrated based on fifty-five specimens collected from the reef regions of Agatti Island, Lakshadweep, Arabian Sea. Urocaridella arabianensis n. sp. is morphologically close to U. pulchella Yokes & Galil, 2006, reported from the Mediterranean Sea. However, the present specimen is clearly distinguished with its rostrum length, which is 1.7 to 2.1 times as long as carapace, 10 ventral rostral teeth, carpus of 1st pereopod is 2.5 times long as palm, carpus of 2nd pereopod is 1.8 times as long as palm, presence of a spine in latero-middle of the fourth and fifth abdomens and the sixth abdominal segment is 2.3 times long as the fifth segment. Partial segment of the mitochondrial COI, 16S rRNA and nuclear gene 18S rRNA and H3 indicates that the new species is sister to a clade comprising of U. pulchella, U. antonbruunii and U. degravei. The pair wise genetic distance of COI showed great distance with the closest congeneric species.
The ‘cleaning rock pool’ shrimp commonly inhabit the shallow waters of reef and crevices regions at 0.5-3.0 m depth. Recent exploration conducted off the Gulf of Mannar and Agatti Island yielded the species, Urocaridella antonbruunii (Bruce, 1967) from the bottom curve of the coral boulder at a depth of 0.5-1.0 m. This is the new record for the Gulf of Mannar and Lakshadweep waters. Major distinguishing morphological characters of the congener's were described and illustrated. The molecular analysis confirmed the species occurrence in Indian waters followed the intraspecific and interspecific genetic divergences (16S gene) were estimated between 0.3-2.1% for within species and 6.4-11.2% for between species respectively. Additionally, we updated and provided the illustrative key characters for all members of the genus Urocaridella.
The genus Anchistus Borradaile, 1898 is a colourful shrimp from the commensal group. In this study, we are reporting a new occurrence of Giant Clam commensal shrimp Anchistus miersi (de Man, 1888 [in de Man, 1887–1888]) caught from Agatti Island, Lakshadweep Sea during February 2020. The present specimens (one each matured male and female) were collected from the mantle cavity of the Giant Clam, Tridacna maxima (Roding, 1798) in the coral lagoon at a depth of 4 m. Anchistus miersi is morphologically very similar to Anchistus demani, which is easily distinguished by the presence of a strong antennal spine and conspicuous accessory spinules in the third─fifth pereopods and presence of small blue spots all over the body. The molecular analysis confirms that, the morphological identification of the present Indian specimens displays an intraspecific genetic divergence of 0.3─1.2%. Besides, the remarkable taxonomic features and colour patterns, distributional ranges are also attested with the report of the species from the present area.
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