First Record of Ozius tuberculosus H. Milne Edwards (Crustacea: Decapoda: Brachyura) from the East Coast of India

The study deals with the widespread distribution of Ozius tuberculosus H. Milne Edwards, 1834 species in Visakhapatnam. Currently, the distribution of O. tuberculosus, covers the Maharashtra, Karnataka, Kerala, the Lakshadweep Islands, and the Andaman and Nicobar Islands, which herein we report the new record from Yarada beach (17° 39’ 17.28’’ N, 83° 16’ 10.92’’ E), Visakhapatnam, Andhra Pradesh as well as east coast of India. Additionally, we provided new details regarding the geographic range of this species in India as well as a taxonomic comparision of Ozius species reported to the country.


Introduction
Among the macro-benthic communities of the maritime habitats, the brachyuran crabs constitute one of the prominent faunal groupings.They are found in most marine habitats such as coral reefs, sandy beaches, rocky beaches, mangroves, and seagrass meadows (Van Tho et al. 2018).
The diversity of marine brachyuran crab in Andhra Pradesh has been reported to be 121 species, belonging to 67 genera, and 27 families (Trivedi et al. 2018;Valarmathi 2020).The family Oziidae Dana 1851 has 7 genera, being 19 species belonging the genus Ozius Milne-Edwards 1834 (Ng 2008).The crabs Ozius guttatus H. Milne Edwards, 1834, O. rugulosus Stimpson, 1858, and O. tuberculosus H. Milne Edwards, 1834 are the only species of the genus reported from India thus far.All three of these species can be found along the west coast, from Kerala to Maharashtra however only the first two species i.e.O. guttatus and O. rugulosus, have been documented on the east coast (Khot et al. 2016;Trivedi et al. 2018).
Based on that, herein the discovery of O. tuberculosis on the east coast of India along with in the state of Andhra Pradesh, as well as its taxonomic keys and overall distribution in India and world, are reported in this paper.As result of the "Faunal Inventorization of the Smart Cities of Andhra Pradesh" project, which is a part of the Indian government's "National Smart City Mission," that consists of numerous surveys conducted all across the Visakhapatnam city.This project's major goal is to catalogue every variety of faunal groups, their diversity, and habitats.The identification of high faunal diversity zones within cities is another objective for better managing and conserving faunal diversity.

Materials and Methods
The samples were collected in January 2022 during the research project "Faunal Inventorisation of Smart Cities of Andhra Pradesh (Amravati and Visakhapatnam)," which surveys were conducted at Visakhapatnam coast, India (Fig. 1).Three males of O. tuberculosus were collected from the intertidal zone at Yarada beach (17° 39' 17.28'' N, 83° 16' 10.92'' E) near Yarada village in Visakhapatnam, India.The specimens were brought to the laboratory and the pleon and gonopods were dissected.Following that, gonopods were examined with an Olympus SZX10 stereo-zoomed microscope, and photographs were taken with a Leica M205 microscope and a Nikon D500 equipped with a Nikkor 40 mm lens kit.Collected specimens were preserved in 10% formaldehyde solution for future references.All morphometric data were recorded by digital caliper (millimeters) (Table 1).A distributional account of this species throughout India as well as throughout the world also prepared along with the taxonomic account.With the aid of identifying keys, the specimens were identified to species level following Alcock (1898), Ng (1998), Davie et al. (2015) and Palomares and Pauly (2016).All the specimens were registered and deposited at the National Zoological Collection, Zoological Survey of India, Freshwater Biology Regional Centre (FBRC/ZSI/M/217).

Diagnostic Characters
Carapace broad, transversely oval, surface rough.Carapace regions of deeply defined.Anterolateral borders of  1 3 carapace divided into 5 teeth, covered by small tubercles.
Frontal teeth divided into four tuberculate protuberances.
Five anterolateral teeth on both sides of carapace.Without lateral spine (Fig. 2A, B).Male chelipeds unequal in size, carpus and palm swollen.Movable finger of bigger cheliped with a tubercle on proximal margin.Finger of bigger cheliped with curved teeth.Five anterolateral teeth on both sides of carapace.Morphometric measurements are given in Table 1.First gonopod stout, little bit straight and sides with setae.Second gonopod whip like, very thin and curled at the apical region, larger than the first gonopod (Fig. 3A-C).

Colour
Male's carapace and pleon region fully purple colored with pearly white and yellowish tubercles on carapace.Eyes black, dactyl umber coloured.Mesogastric region of the carapace having "U"-shaped white coloured spot.Coxa of pereopods umber to light yellowish (Fig. 2A-F).

Habitat
Typically inhabits rocky intertidal shores, living between rocks in these areas (Fig. 4).

Discussion
The state of Andhra Pradesh is rich in biodiversity due to its extensive coastal reach and the biggest proportion of the Eastern Ghats.Sandal, rocky, patchy coral, and mangrove habitats are the crowning attributes of its coastal ecology.The majority of decapods exhibit cryptic behavioral patterns, which evolved in many animals that match the visual background to avoid detection (Uy et al. 2017).In India, along with O. tuberculosus, two more species of the genus are encountered,-: O. guttatus and O. rugulosus.All three of these species significantly prefer to live on rocky seashores and in the crevices between rocky outcrops.Because of the colour of the carapace, they can camouflage among the rocks for protection and to catch prey.Ozius tuberculosus also known as "Beaded rock crab" for living rocky habitats.Ozius guttatus is reddish to dark brown, the carapace is smooth which distinguishes it from the other two species found in India.The carapace of O. rugolosus has fine granules and ridges like that of O. tuberculosus, but the posterior half of the carapace is smooth, unlike of O. tuberculosus that the posterior half of the carapace is very rough and pigmented with grooves.In O. rugolosus the right cheliped is significantly larger and more robust than the left, compared to O. tuberculosus, which having slightly unequal Chelipeds with sub equal finger in right cheliped.The species Ozius  1834, Yarada beach (17° 39' 17.28'' N, 83° 16' 10.92'' E), Visakhapatnam, Andhra Pradesh, India tuberculosus has numerous white pigmentations on the carapace, which the other two species from India lacking.Ozius tuberculosus type locality is Mauritius, and it is distributed from the Indian Ocean to the east China Sea to the Cora Sea in the southern hemisphere (Fig. 5).The distribution of this species is primarily found in the south Asian countries and in one country in Oceania, i.e.New Caledonia (Fig. 5).In India, Maharashtra, Karnataka, Kerala, and Lakshadweep Islands are the three southwestern states and Union Territory from which O. tuberculosis has previously been recorded (Fig. 1).Its distribution is visible in another the Union Territory, the Andaman and Nicobar Islands, in the eastern region of India.This species was mentioned in the studies of several researchers, including Henderson (1893), Alcock (1898), Forest andGuinot (1961), Serene (1984), Tweedie (1950), Poupin (1996), Ng (1998, 2008), and Dineshbabu et al. (2011).Later, the same species were listed from Kerala and Maharashtra, respectively, by Dev Roy (2013) and Khot et al. (2016).
Even yet, there is a distinction in the colour pattern between the species found in the west and east coasts.The colour pattern of Ozius tuberculosus, which ranges from umber to red (Fig. 2), is clearly visible in all specimens that were collected from the western shore and documented in earlier works (Khot et al. 2016).But what we have here is very different from that, with a carapace and pleon that are entirely purple.This pattern of coloration may be due to environmental influences such salinity, temperature, pH, and habitat preferences.Considering the length of the shoreline and the variability in environmental circumstances, the number of species reported from Visakhapatnam is remarkably low.Therefore, more thorough studies should be conducted to understand more about the true diversity of marine brachyurans in this region.

Fig. 2
Fig. 2 Male specimens of Ozius tuberculosus H. Milne Edwards, 1834 (FBRC/ZSI/M/217), A and C Dorsal and ventral view -showing colour in life.B and D Dorsal and ventral view of preserved specimen.E Male pleon of preserved specimen.F Frontal view of preserved specimen

Table 1
Morphometric measurements of Ozius tuberculosus H.Milne Edwards 1834 collected from Andhra Pradesh, India