Researchers discover a new fish species endemic to Bhutan

Parachiloglanis bhutanensis - most recent add to the fish diversity in Bhutan
Parachiloglanis bhutanensis – most recent add to the fish diversity in Bhutan

During a recent collaborative research project of documenting fish diversity in the country, researchers from the College of Natural Resources (CNR), Bhutan and Saint Louis University, USA, discovered a new species of torrent catfish from Khalingchhu in the eastern part of Bhutan. It is the first endemic fish species to Bhutan, found nowhere else in the world. The fish was named Parachiloglanis bhutanensis in honor of the country in which it is endemic to.

The common name now given to the fish is the Khaling Torrent Catfish. R.J. Thoni, a PhD student at Saint Louis University along with Dr. D.B. Gurung, Assistant Professor in CNR, conducted the scientific examination and discovered it has never been recorded before. In an article they published in the scientific journal ZOOTAXA, they wrote, “The common name, Khaling Torrent Catfish is in reference to the village of Khaling, through which flows the stream where it was discovered”. The researchers discovered the catfish about 1 km east of the village of Khaling.

The endemic fish has flat body with broad, blunt and rounded head, rising at roughly a 45-degree angle from snout to point vertical with eye. The fish measures 101mm from the tip of snout to the end of tail. Researchers also recorded the fish as having other features such as thick and leathery fins. The ventral view of the mouth and snout resembles the shape of a hammer or bell, one of the body parts that makes it an interesting fish. Such a shape is due to the posterior flap of tissue connecting maxillary barbel to mouth.

Another important aspect this study has made is that the genus Parachiloglanis was earlier recorded as having only one species P. hodgarti. But now, “with the discovery of P. bhutanensis, the genus Parachiloglanis is no longer monotypic”. This means that now there are two species under the genus. The scientists described two species having many differences between them. “They differ in meristic, mensural, and coloration characters.” Further, Parachiloglanis bhutanensis is confirmed as a member of the genus by the absence of a post-labial grove on the lower lip, which is present in other genera of the subfamily Glyptosterninae.

Khalingchhu where the fish was discovered
Khalingchhu where the fish was discovered

During their studies, R.J. Thoni and Dr. D.B. Gurung found that the newly discovered endemic fish is known from Khalingchhu stream and an adjacent, unnamed stream in the headwaters of the Dangmechhu River, in the Brahmaputra drainage. However, they didn’t rule out its presence in other streams in other parts of the Country.

R.J. Thoni and Dr. D.B. Gurung, in their scientific report stated that Parachiloglanis bhutanensis was discovered in a high-velocity, small order stream at 2211 m above sea level. But unlike its congener in similar streams, they were found in low numbers. Even with several hours of effort of trying to net as many live specimen as possible, they could collect only three specimens. The researchers claim that this may indicate that the fish does not occur in high abundance.

Like its sibling species, the newly discovered fish is known to adhere to the bottom side of boulders, favoring areas of cascades and white water rather than pools. “They were associated with large rocks with deep undercut areas versus rocks with only small refuge from the current”, writes the researchers. They also described the two streams in which they were found as having clear, cold-water, sourced from mountain springs, precipitation runoff, and snowmelt. The streams are found to have little algal growth and frequent high-flow events. “This species is adapted to a high-velocity environment with adhesive striations on the leading rays of the paired fins for clinging to rocks and an inferior mouth adapted for scraping algae and invertebrates from the substrate”.

They described the discovery as very important milestone in conserving fish diversity of Bhutan. They pointed out that due to its small range and low density, as well as the highly stochastic and increasing nature of floods and droughts in streams of this region, P. bhutanensis may be a species of conservation concern.

The researcher hope that further research will be conducted to determine its range and understand its biology and life history to ensure its existence far into the future. Doing so, they said will be beneficial in understanding and conserving the species in the Country.

According to Dr. D.B. Gurung, the number of fish diversity recorded in Bhutan has gone up to 93 species from the previous record of 52. With few more unidentified taxa, which are yet to be determined, the diversity of fishes found in Bhutan will cross over 100. The study is being continued to make an exhaustive documentation of the fish diversity in the country. The documentation is important from the perspective of climate change and a number major hydropower projects being developed around country, which will have direct impact on the fish diversity and its population structure.

Reported by: Ugyen Tshering and Photos by R.J Thoni,

 

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