Science1 publisher2 min readPublished
Brazilian researchers recommend Endangered for an orange killifish they have just named
Laimosemion laranja is known from three small forest pools near Laranjal do Jari, a range of about 25 square kilometres, and the paper describing the fish also argues it meets the IUCN criteria for Endangered.
The Scientist · Science desk
What happened
- Researchers have described Laimosemion laranja, a killifish under 3 centimetres in standard length, from forest streams in the Rio Cajari drainage of Amapá state, reporting it in Zoosystematics and Evolution.
- Males carry rows of orange spots along the front half of the body and bold chevron-shaped orange bars toward the tail, set against a pale gray flank.
- Establishing that the fish was new took comparison of body proportions, scale counts and skeletal features against its closest relatives, plus an analysis of its mitochondrial DNA.
- The species is known from three small forest pools near Laranjal do Jari, all of which show signs of disturbance from deforestation, mining and urban expansion.
- Its entire known range covers an estimated 25 square kilometres, which the authors argue is enough to meet the criteria for an Endangered listing under IUCN guidelines.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- decision The authors ask for a boundary change, extending the neighbouring Rio Cajari Extractive Reserve. The next move available for this fish is a state protected-area decision.
- constraint The paper does not give an abundance figure. An assessment can only weigh range extent against observed threats, and a later population count could push the category in either direction.
- precedent A description that arrives with a threat recommendation invites assessors to act on a single field campaign's records. For a narrow endemic, those records are the quickest route to a formal category and the thinnest basis for one.
Twenty-five square kilometres is the area of a square five kilometres on a side. Two of the three pools inside that area come with a named pollution source: one lies close to water discoloured by mining sediment, and another, within the city, is affected by plastic pollution. All three show disturbance. Those three pools are every locality on record for this fish.
The fieldwork was done by researchers from the Universidade Federal do Rio Grande do Norte, the Instituto Peixe das Nuvens, the Universidade Federal do Pará and the University of West Florida. Yuri Abrantes of the Universidade Federal do Rio Grande do Norte led it. "During our sampling in small rivers locally known as 'igarapés' in the Rio Cajari region, in Amapá state, we found this fish with a very striking coloration, which immediately caught our attention," he said.
"Laimosemion represents one of the five independent origins of the annual life cycle within the family Rivulidae," Abrantes said. In that group, some species can pause embryonic development entirely, lying dormant in damp mud until seasonal pools refill with rain. That trait is reported for the group. If laranja shares the annual cycle, then how many pools a survey finds it in depends on when in the season the survey happens.
The name is Portuguese for both the colour orange and the fruit, and it honours Laranjal do Jari, the municipality where the fish was found. Abrantes said that once the genetic analysis confirmed the fish's distinct identity, "it was something special, as we saw an opportunity to contribute to increasing our knowledge of Amazonian biodiversity and to draw attention to the conservation of areas that are still poorly explored but highly threatened." The description and the conservation argument came out of one field campaign and the same three pools. One paper cannot settle whether that pairing is now routine for narrow-endemic freshwater fishes; answering that would take a count of recent descriptions carrying threat recommendations.
What to watch
- Whether IUCN assessors take up the recommendation, and whether they assign Endangered or a different category.
- Any decision by Amapá on extending the boundaries of the Rio Cajari Extractive Reserve.
- A fourth or fifth locality outside the three sampled pools, which would move the 25-square-kilometre range estimate.