Flasher wrasse (Paracheilinus nursalim)

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Male and female Paracheilinus nursalim
IUCN Red List species status – Least Concern LEAST
CONCERN

Top facts

  • Paracheilinus nursalim is a small Indonesian fish with particularly bright colouration.
  • Paracheilinus nursalim belongs to a group known as ‘flasher wrasses’, as the males ‘flash’ their vivid colours during courtship.
  • Paracheilinus nursalim was first discovered in 2006, and only formally described as a new species in 2008.
  • The female Paracheilinus nursalim is less brightly coloured than the male.
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Flasher wrasse fact file

Flasher wrasse description

KingdomAnimalia
PhylumChordata
ClassActinopterygii
OrderPerciformes
FamilyLabridae
GenusParacheilinus (1)

A small Indonesian fish, Paracheilinus nursalim belongs to a genus commonly known as flasher wrasses due to their vivid colouration, which is ‘flashed’ by the males during courtship displays. This colourful fish was first discovered in 2006 during a survey by Conservation International, and was formally described as a new species in 2008 (2).

The male Paracheilinus nursalim is usually dull reddish overall, fading to yellow on the belly and with a dusky grey area on the top of the back. There is also a black rectangular patch on the underside of the body, just before the tail. Each side of the male’s body has five narrow, red-brown stripes running along it, while a blue to purplish stripe runs below the eye, from the lip to the lower part of the operculum. The eyes of Paracheilinus nursalim are yellow (2).

As in other members of the genus, males of Paracheilinus nursalim have long, tapering, filamentous extensions on around four to six of the rays of the dorsal fin. In this species, the dorsal fin is reddish-orange, with pinkish-red fin rays, while the pelvic fins, tail fin and broad anal fin are largely reddish. The tail fin of the male Paracheilinus nursalim has unusually long, trailing, filamentous extensions (2).

During courtship, the male Paracheilinus nursalim undergoes a dramatic colour change, becoming orange overall and fading to whitish or pink on the upper side of the body. The conspicuous dark patch near the tail develops a bright blue stripe along its upper edge, and a second, less distinct dark patch becomes apparent on the upper back. In addition to the faint red stripes along the sides, the male Paracheilinus nursalim develops several bright blue stripes on the body and head, including one along the base of the dorsal fin (2).

The dorsal fin of the male Paracheilinus nursalim turns yellowish to pinkish-white and has a sky blue margin during courtship, while the anal fin and pelvic fins become wine red, with a blue edge to the anal fin. The tail becomes translucent, with blue speckling and with pinkish-white filaments, and the pectoral fins turn a translucent yellowish colour (2).

In contrast to the male, the female Paracheilinus nursalim is largely pinkish-red with yellow mottling, and has a series of yellow blotches along the base of the dorsal fin. Each side of the female’s body has four to five bluish or violet stripes, with irregular rows of blue or violet spots in between. Two blue to violet stripes extend backwards from the eye, and the female also has a light blue line running below the eye to the side of the breast. The dorsal fin and tail fin of the female Paracheilinus nursalim are yellowish with narrow blue bands and spots, while the anal fin is red with blue spots and the pelvic fins are whitish to pink (2).

Paracheilinus nursalim is most easily distinguished from other members of its genus by the dark patches on the back and near the tail of the adult male, which are not present in other species (2).

Size
Length (excluding tail): up to 5.1 cm (2)
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Flasher wrasse biology

Relatively little information is currently available on the biology of Paracheilinus nursalim. Like other wrasses (Labridae species), this species has prominent canine teeth in the front of its mouth (2) (3), but it may resemble other Paracheilinus species in feeding predominantly on zooplankton (4).

In general, wrasses are active during the day, taking shelter in crevices in the reef or burrowing into the sediment at night (3). Large aggregations of Paracheilinus nursalim have sometimes been encountered, numbering around 30 males and several hundred females (2). As in other wrasses, the males of this species may dominate a group of females (3) (5).

The males of Paracheilinus nursalim perform a dramatic courtship ritual in which neon-like courtship colours are repeatedly ‘flashed’ to attract females (2) (6). This bright display is further enhanced by bouts of rapid swimming, interspersed with stationary periods during which the male erects the dorsal and anal fins (2). The male’s flashy courtship display is most commonly performed about an hour before sunset, and continues until dusk (2) (6).

Other details of the breeding behaviour of Paracheilinus nursalim are not yet known, but the male is reported to guard the eggs and sometimes also the newly hatched juveniles (6). As in most wrasses, it is likely that the female Paracheilinus nursalim undergoes a remarkable change as it grows, starting life as a female and developing into a male once it reaches a certain size (3) (5). Female specimens of this species have been recorded with a standard length of 2.1 to 2.9 centimetres, while male specimens have had a standard length of 3.9 to 5.1 centimetres (2).

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Flasher wrasse range

Paracheilinus nursalim is known only from the western central Pacific Ocean, where it occurs around Bird’s Head Peninsula in western New Guinea, Indonesia (1) (2). It has been recorded from southeast Misool in the Raja Ampat group of islands, south-eastwards to Triton Bay (2).

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Flasher wrasse habitat

An inhabitant of coral reefs, Paracheilinus nursalim is found in partly sheltered areas that are periodically exposed to strong currents, and is associated with gradual rubble slopes. Paracheilinus nursalim has been found at depths of 5 to 50 metres, but is most common between 20 and 35 metres. However, large aggregations have sometimes been found at depths of 6 to 10 metres in Triton Bay (2).

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Flasher wrasse status

Paracheilinus nursalim is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern

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Flasher wrasse threats

Very little is currently known about Paracheilinus nursalim, and this recently discovered species has only been recorded in a small area of Indonesia. However, this colourful fish is considered to be locally abundant, and no major threats to its population are known at present (1).

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Flasher wrasse conservation

There are currently no conservation measures specifically in place to conserve Paracheilinus nursalim. However, it occurs in several Marine Protected Areas across its range, which may offer it some protection (1).

Paracheilinus nursalim was initially discovered during a marine survey by Conservation International (2). The surveys performed by this organisation around the Bird’s Head Peninsula have led to the discovery of many new species and shown the area to be a global priority for marine conservation. New Marine Protected Areas have been created as a direct result of this work, and the survey results have been used to inform management plans and government policies in the region (7).

In addition, worldwide publicity surrounding the new species discoveries has increased awareness and local pride in the region’s marine environment. It has also helped to expand marine tourism and in turn raise funds for local people. The publicity was also a key factor in the success of the ‘Blue Auction’, an event which raised vital funds by auctioning off the rights to name ten of the new fish species discovered by Conservation International’s surveys (7).

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Find out more

Find out more about Paracheilinus nursalim:

Find out more about Conservation International’s Rapid Assessment Program:

Learn more about newly discovered species on ARKive:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Anal fin
In fish, an unpaired fin on the under surface of a fish, behind the anus.
Dorsal fin
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
Genus
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Operculum
In fish, a hard, bony flap that covers and protects the gills.
Pectoral fins
In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
Pelvic fins
In fish, the pair of fins found on the underside of the body.
Standard length
In fish, the length from the snout to the base of its tail (caudal) fin.
Zooplankton
Tiny aquatic animals that drift with currents or swim weakly in water.
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References

  1. IUCN Red List (January, 2013)
    http://www.iucnredlist.org/
  2. Allen, G.R. and Erdmann, M.V. (2008) Paracheilinus nursalim, a new species of flasher wrasse (Perciformes: Labridae) from the Bird’s Head Peninsula of western New Guinea with a key to the species of Paracheilinus. Aqua, International Journal of Ichthyology, 13: 179-188.
  3. Carpenter, K.E. (2002) Labridae. In: The Living Marine Resources of the Western Central Atlantic. Volume 3: Bony Fishes Part 2 (Opistognathidae to Molidae), Sea Turtles and Marine Mammals. Food and Agriculture Organization of the United Nations, Rome. Available at:
    ftp://ftp.fao.org/docrep/fao/009/y4162e/y4162e39.pdf
  4. Spalding, M.D., Ravilious, C. and Green, E.P. (2001) World Atlas of Coral Reefs. UNEP World Conservation Monitoring Centre, Cambridge, UK and University of California Press, Berkeley, California.
  5. FishBase: Family Labridae - Wrasses (January, 2013)
    http://www.fishbase.org/summary/FamilySummary.php?id=362
  6. Conservation International (2011) 20 years, 20 ‘RAP stars’, and ‘still counting’… Conservation International Press Release, 13 April. Available at:
    http://www.conservation.org/newsroom/pressreleases/Pages/20_Years_of_RAP_Still_Counting.aspx
  7. Alonso, L.E., Deichmann, J.L., McKenna, S.A., Naskrecki, P. and Richards, S.J. (Eds.) (2011) Still Counting…: Biodiversity Exploration for Conservation - The First 20 Years of the Rapid Assessment Program. Conservation International, Arlington, Virginia. Available at:
    http://www.conservation.org/Documents/CI_RAP_20_Year_Still_Counting_discoveries.pdf
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Image credit

Male and female Paracheilinus nursalim  
Male and female Paracheilinus nursalim

© Tim Laman / naturepl.com

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