First report of brittle stars (Echinodermata: Ophiuroidea) from a seamount in the eastern Arabian Sea.

This paper reports two species-Ophiozonella molesta (Koehler, 1904) and Ophiothamnus venustus Matsumoto, 1915, from a seamount in the Eastern Arabian Sea. This forms the first ever report of Ophiothamnus venustus from the Indian Ocean, and the first verified report of Ophiozonella molesta from Indian waters. This is the first ever work to document benthic invertebrates from seamounts in the Arabian Sea.

Response of macrozoobenthic communities to summer monsoon upwelling and related hypoxia in the south eastern Arabian Sea shelf.

Coastal upwelling in the south eastern Arabian Sea (SEAS) leads to oxygen depletion over the continental shelf during the summer monsoon season (June-September), with latitudinal gradients in intensity. Based on two surveys in the onset (June) and peak (August) phases of the summer monsoon, the present study evaluates the response of macrozoobenthic communities (size >500 µm) to upwelling and consequent hypoxia (dissolved oxygen <0.2 ml/l) in the central sector of the SEAS shelf (10-12°N, 30-200 m). From the onset to the peak monsoon, macrozoobenthic density increased five-fold in the mid-shelf (50 m water depth), and nearly doubled in the outer shelf (100 m water depth) and shelf edge (200 m water depth). This was found to be a direct consequence of recruitment and proliferation of opportunistic polychaetes, particularly the spionid Paraprionospio pinnata, which was the single dominant species (52-78%) at all depths during the peak monsoon. With the establishment of the monsoon, the shelf communities (particularly 50-100 m depth sites) are thus transformed from relatively diverse assemblages to dense, single-species dominated ones. The shelf-edge communities (150-200 m depths), which are impacted with the perennial Arabian Sea oxygen minimum zone, and therefore harbour opportunist-dominated communities year-round. It is postulated that larvae of hypoxia-tolerant taxa are transported from the shelf edge by the process of upwelling onto the shelf. The settlement and survival of these larvae are regulated by the nature of shelf sediments and by the prevailing hypoxia. Thus, substantial recruitment of opportunists occurred in the outer and mid-shelf (50-100 m), but not in the inner shelf (30 m), where sedimentation from river discharge hindered settlement and survival of juveniles.

New records of brittle stars (Echinodermata: Ophiuroidea) from the Lakshadweep atolls, northern Indian Ocean, with notes on Indophioderma ganapatii Sastry, Marimuthu amp; Rajan, 2019.

The paper presents three new records of brittle stars for Indian waters, collected from the Lakshadweep atolls (northern Indian Ocean)-Ophiarachnella septemspinosa (Müller Troschel, 1842), Ophiocoma cynthiae Benavides-Serrato O'Hara, 2008 Ophiomoeris obstricta (Lyman, 1878). Further, this paper also discusses the validity of two recently described taxa from this archipelago, the genus Indophioderma with the species Indophioderma ganapatii Sastry, Marimuthu Rajan, 2019. A checklist of brittle stars reported so far from the Lakshadweep Islands is provided, which includes 40 valid species-32 from shallow (reef) areas and 8 deep-sea (>200m) species.

The Shallow-water Crinoid Fauna of Lakshadweep Atolls, North-western Indian Ocean.

A biodiversity survey carried out from 2016 to 2018 by the Department of Science and Technology in the Lakshadweep Atolls, India, recorded six species of shallow-water feather stars new to the archipelago (Comanthus wahlbergii, Comaster schlegelii, Himerometra robustipinna, Dichrometra palmata, Stephanometra indica, and Phanogenia typica). Himerometra sol A.H. Clark, 1912, previously known only from the Maldive Islands, is synonymized under Himerometra robustipinna (Carpenter, 1881). This study brings the total number of shallow-water crinoids recorded from Lakshadweep to ten species. Of the four species collected previously from the archipelago, only Comatella nigra was found in this survey. Of those not collected, Comatella stelligera and Oligometra serripinna are widespread in the Indo-western Pacific region, whereas Heterometra compta is known only from Lakshadweep, and its validity remains uncertain. The known shallow-water crinoid fauna of the archipelago is substantially less diverse than that of the adjacent and environmentally similar Maldive Islands, emphasizing the need for additional research in this island group, in particular, to determine whether the differences are actual or not, and whether they are based on natural conditions versus anthropogenic impacts.