Zoological Survey of India Scientists Describe Tetronarce ramanamurthyi, a New Deep-Sea Electric Ray From the Arabian Sea and the First of Its Genus Confirmed in the Northern Indian Ocean

On 19 October 2026 the journal Zootaxa published the description of a new electric ray, Tetronarce ramanamurthyi, based on nine specimens from deep water in the southeastern Arabian Sea. The abstract and the Zoological Survey of India (ZSI) both call it the first confirmed record of the genus Tetronarce in the northern Indian Ocean. ZSI announced the find on 27 October 2026 in a release carried by the Press Information Bureau (PIB), and the researchers give it the common name Arabian Black Electric Ray.

The paper has three authors. K K Bineesh, a Scientist E, and Anil Kasinath, a junior research fellow, work at ZSI’s Marine Biology Regional Centre in Chennai. David A Ebert of the Pacific Shark Research Center at Moss Landing Marine Laboratories, San Jose State University, is the third. The paper runs from page 557 to 570 of volume 5890, issue 4. As of 5 November 2026 the full text sits behind a subscription, so this article rests on the published abstract, the PIB release and a database entry that summarises the paper’s diagnosis.

A fish from the shrimp trawlers’ catch

Research Matters, summarising the paper, reports that fishermen brought the rays up as bycatch, meaning fish caught by accident, from deep-sea trawl fisheries that target red shrimp. The depth was 400 to 700 metres. The researchers collected the specimens during fish-landing surveys at Sakthikulangara Fishing Harbour in Kerala. The PIB release is less specific and says the specimens came from off India’s south-western coast, and the abstract says deep water off the southeastern Arabian Sea. The Shark-References database, which reproduces the paper’s diagnosis, lists the same depth range of 400 to 700 metres.

Sakthikulangara is in Kollam district. The Central Marine Fisheries Research Institute’s repository records that a few entrepreneurs there launched three medium deep-sea trawlers in September and October 1988, aimed at deep-sea prawns and lobsters beyond 50 metres of water. Monitoring surveys at the same harbour supplied three of the four specimens of a catshark that the same ZSI centre described in June 2026, covered below.

How the ray is told apart

Most of the fish’s features are small and measurable, and the abstract says no single one separates it from its relatives. It names a combination.

• The back is a uniform dark bluish-black or dark brown, and the belly is whitish.
• The disc, the broad rounded body formed by the enlarged pectoral fins, is wider than it is long, between 1.0 and 1.2 times as wide as long.
• There are no papillae, small fleshy bumps, around the spiracles, the breathing openings behind the eyes.
• The spiracles are relatively large, 3.9 to 5.1 per cent of total length, and nearly equal to the eye in size.
• The endolymphatic pores, small openings on top of the head linked to the inner ear, are relatively large at 1.2 to 1.6 per cent of total length.
• The electric organs are smaller than in its relatives, 23.3 to 28.9 per cent of total length long and 10.6 to 13.8 per cent wide.
• There are 99 vertebrae, counted as 30 monospondylous and 69 diplospondylous.

Smooth spiracle edges are not unique to the new species. The Florida Museum describes the Atlantic torpedo, Tetronarce nobiliana, as having spiracles with no tentacles or papillae, so the abstract relies on the combination.

The Shark-References entry, citing the paper, calls it a medium-sized species. The largest specimen was a female of 771 millimetres in total length. The holotype, the single specimen that carries the name, is a mature male of 525 millimetres, catalogued as ZSI MBRC/F/3305. The entry lists nine catalogue numbers for the type material, all in ZSI’s Marine Biology Regional Centre collection.

What the DNA adds

The team also sequenced two mitochondrial genes, COI and ND2. Mitochondrial DNA is the genetic material in a cell’s energy-producing structures, and a short stretch of it works as a barcode for telling species apart. The PIB release says the sequences confirmed the ray as a distinct evolutionary lineage. In the COI comparison the gap to related species ran from 2.2 per cent, measured against Tetronarce tokionis, to 6.7 per cent, measured against T. nobiliana. Research Matters says the lineage is well separated from every other known electric ray species in the world.

The Atlantic torpedo is the genus’s best-known member, and the Florida Museum gives its discharge as 170 to 220 volts. Neither the abstract nor the PIB release reports a voltage for the new species, only that its electric organs are small.

The name honours the Deep Ocean Mission director

The species is named for Dr M V Ramana Murthy, Mission Director of the Deep Ocean Mission at the Ministry of Earth Sciences. The PIB release says the name recognises his outstanding contributions to marine science, ocean engineering and marine hazard mitigation in India. The spelling in the paper’s title, which Crossref’s record also carries, is ramanamurthyi. Some newspaper reports, among them The Hitavada, print it as “Ramanamurthy”.

The work was done under that mission. The Cabinet Committee on Economic Affairs approved the Deep Ocean Mission on 16 June 2021 at an estimated Rs 4,077 crore over five years, with six components, one of them on exploring and conserving deep-sea biodiversity. ZSI’s project under it studies the taxonomy, distribution, biology and status of deep-sea chondrichthyans, the cartilaginous fishes: sharks, rays and their relatives. The mission’s submersible and robot work is covered in India’s deep-sea robots and the Matsya 6000 submersible.

One of several finds from the same coast

The electric ray follows a catshark from the same centre. On 9 June 2026 Zootaxa published Apristurus drona, described by Sweta Beura, Bineesh and Dhriti Banerjee from four specimens of 439 to 473 millimetres collected off the Kollam slope at 400 to 650 metres. Mongabay India quotes Bineesh saying the surveys have shown that understanding of deep-sea biodiversity is limited. ZSI’s other recent taxonomy, such as three new centipedes from Kerala and Coorg, is work on land.

The Kollam slope is an Important Shark and Ray Area, a designation from the IUCN’s Shark Specialist Group. Its 2023 factsheet draws the area at 200 to 1,000 metres depth over 5,549 square kilometres, and lists the critically endangered dwarf gulper shark and Indian swellshark among the species found there. The factsheet does not mention the new ray, and the paper’s abstract does not place the ray on that slope.

Mongabay also reports Bineesh’s account of the fishing. With rising demand for deep-sea shrimp, trawlers that once worked 200 to 400 metres now operate down to about 600 metres, and he links the recent appearance of the catshark in catches to that deeper fishing.

What is still open

The abstract says the species is so far known only from the southeastern Arabian Sea. None of the sources reviewed gives a population estimate or a conservation status for it, and the paper describes the fish rather than assessing how it fares under fishing. Nine specimens is a small base for judging range or abundance.

The ZSI release says continued deep-sea exploration under the Deep Ocean Mission is expected to yield further discoveries and to widen knowledge of biodiversity in the northern Indian Ocean.