The genus Lysiosquillina contains 04 species that are difficult to identify the morphological characters. More over these characters are not enough to the accurate identification of the species level. In the present study, the mtDNA sequences of COI gene of the mantis shrimp Lysiosquillina maculata belongs to the family Lysiosquillina were initially compared with same genus of 03 different species like, L. glabriuscula (Lamarck 1818), L. lisa Ahyong and Randall (2001) and L. sulcata (Manning 1978b). It was the first conformational record in Indian waters. The GenBank accession number is MT490885. A 650bp segment of the 5’ margin of mitochondrial cytochrome oxidase subunit I gene is currently used for classification of molecular taxonomy. The A,T,G and C contents of the sequence L. maculata were 154%, 140%, 86% and 51% respectively. The GC content was observed at 31.8% in the species. Other sequence variation was not observed among those specimens.
In the present study we have examined the morphological characters and identified the specimen as Lysiosquillina maculata (Fabricius 1793). We recorded two specimens with total length ranged from 161 to 178 mm and the specimens are having the characters of ocular scales triangular, erect, and inclined anteriorly. The carapace is convex and broad the rostrum is cordiform-shaped occasionally sub triangular, width usually greater than length. The blunt longitudinal carina present on anterior third plate. Dactylus of raptorial claw possessing 8-11 teeth; normally 10-11 but the larger females it may be varied in 10-11 teeth. Mandibular palp present and 3 segmented. TS8 sternal keel rounded. Uropodal protopod is triangular lobe and ventero laterally anterior to articulation of each uropod and uropodal exopod proximal segment outer margin with 7–9 movable spines; endopod with distal ¾ dark. Dorsum base colour pale yellow, with black transverse bands.
The genetic information of taxonomically identified species is essential for perform the genetic similarity search in the global database (Moritz and Cicero 2004). Hence, before submitting any novel sequences in GenBank and BOLD, it is essential to identify the studied specimens. Earlier, the genetic information on the two known species of genus Harpiosquilla, H.harapax and H. raphidea are accessible in the GenBank database. The generated sequence of L. maculata from Indian waters were first time annotated (650 bp) and submitted in to the GenBank datasets. The generated sequences are shown 91% similarity with Lysiosquillina maculata in both GenBank and BOLD database.
The genetic distance of L. maculata with eight closely related species were calculated based on Kimura’s 2-parameter method (Table 1). The pair wise genetic distance was calculated it varied from (0.03-0.404) that showed the smaller genetic distance indicate a close genetic relationship whereas a large genetic distance indicate a more distant genetic relationship. Genetic variation within populations can be lost through genetic drift or bottleneck in the population (You et al. 2001). Hebert et al. (2003) suggested that DNA bar coding has the powerful tool to provide valuable insight in to patterns of genetic divergence affected by species level or ecological variation. The average genetic distance among species does not exceed the average genetic distance between “sister” species.
The phylogenetic relationship of Lysiosquillina maculata with 01 closely related species and one out group were analysed in this study. Complete mitochondrial genes of these 04 species are available on GenBank. The maximum-liklihood evolutionary tree (ML tree) was constructed by MEGA 7 (Kumar et al. 2016) based on 1st and 2nd codon sequences of 19 protein coding genes.
In the ML phylogenetic tree, Lysiosquillina maculata and Harpiosquilla harpax formed one clade with strong support. But Oratosquilla oratoria, Traisquilla profunda, Heterosquillatri carinata, Austrosquilla tsangi, Platysquilla eusebia, Madeirasquilla tuerkayi and Lysiosquilla maculata in the second clade. These two clades mentioned above were all classified into family Lysiosquillidae or order Lysiosquilloidea (Fig. 1). All the above results shows that L. maculata has close phylogenetic relationship to H. harapax. As expected, species from the same genera were clustered in to a two different clades with well supported bootstrap proportion (Steinke et al. 2005).