Scientists have discovered a new species of blind and blood-red eel from two non-descript dug-out wells located in a village in Assam’s Goalpara district. The species has been given the name Rakthamichthys anchi.
The discovery was announced in a research paper titled 𝑅𝑎𝑘𝑡ℎ𝑎𝑚𝑖𝑐ℎ𝑡ℎ𝑦𝑠 𝑎𝑛𝑐ℎ𝑖, a new species of phreatobitic synbranchid eel from Assam. It has been published in the journal Zootaxa.
The research was led by Ralf Britz of the Senckenberg Natural History Collections in Dresden, Germany, along with scientists from Assam Don Bosco University, Dhanamanjuri University in Manipur, and other institutions.
One of the specimens was collected during the village’s annual well-cleaning exercise. The other was captured using a baited trap in an abandoned well nearby.
Interestingly, these wells are about 1.5 metres wide and roughly 7 metres deep, with water sitting around 2.5 metres below the surface without sunlight. This may be the reason why the eel lost its sight entirely, and its body carries no pigment at all. Its blood red colour, which gives the species its name, actually comes from blood vessels showing through its almost transparent skin. In fact, the name anchi is a Garo word meaning ‘blood’.
The Rakthamichthys genus of phreatobitic (residing exclusively within the phreatic zone of groundwater aquifers) swamp eels (Synbranchidae) is endemic to India. After Rakthamichthys rongsaw, Raktℎamicℎtℎys ancℎi is now the second swamp eel of the genus to be discovered in the Northeast.
The other four members of the genus have been recorded from wells and groundwater aquifers in the Western Ghats, thousands of kilometres away in western and southern India.
Recently, Gitchak nakana Britz, the first groundwater-dwelling fish from Northeast India, was found in this same region.
To study the eel, the team also performed different 3-D X-rays. This way, they were able to see the internal parts of the animal through CT scans without harming it. From 37,500 described species of fishes, just over 300 have adapted to a permanent life underground.
The scientists also found a unique feature in R. anchi. In the ‘caudal’ or posterior area, the last vertebra articulates with a single paired bony splint, which they identified as a caudal fin ray. The caudal fin ray is a supportive skeletal rod in a fish’s tail fin, made of segmented bone and skin tissue that helps the fish swim and steer
Caudal fin rays are absent in all adult synbranchids or swamp eels studied so far, with the exception of Macrotrema native to Malaysia and Thailand.
Because only a handful of Rakthamichthys eels have ever been found, and only in this one village so far in the Northeast, the researchers have chosen not to reveal its exact location publicly. They are being cautious, worried that too much attention could put the fragile population at risk.
Other authors of the paper besides Britz include Amanda K Pinion, Wimarithy K Marak, Kangjam Velentina and Yumnam Lokeshwor.