Thursday 9 August 2012

Two new species of Asian Sea Bass from South Asia.

Freshwater Perch of the genus Lates are large carnivorous fish found in Africa, Asia and Australia. The best known African species is the Nile Perch, Lates niloticus, but there are a number of other species in the lakes and rivers of East Africa and Arabia. Further east there are only two species recognized, the Japanese Perch, Lates japonicus, and the Barramundi or Asian Sea Bass, Lates calcarifer, which is found from the Persian Gulf to Northern Australia. Lates calcarifer is not completely tied to freshwater, as it breeds in brackish estuarine or even shallow marine waters and fully marine populations are known, though it is generally considered a river fish. This ability to live in seawater helps to explain the wide distribution of Lates calcarifer, but it has long been suspected that the species might in fact be made up of a number of cryptic species; populations apparently identical but genetically distinct and incapable of interbreeding.

In a paper published in the journal Zootaxa on 16 May 2012, Rohan Pethiyagoda of the Australian Museum in Sydney and Anthony Gill of the Macleay Museum and School of Biological Sciences at the University of Sydney present the results of a genetic survey of 'Lates calcarifer' from Australia, India, Malaysia, Myanmar (Burma), Singapore, Sri Lanka and Thailand, which uncovered two new, cryptic, species in Sri Lanka and Myanmar, which are formally described in the paper.

The original illustration of Lates calcarifer (or Holocentrus calcarifer as it was originally called); the precise origin of this fish is unclear. Bloch (1790)/Pethiyagoda & Gill (2012).

The first new species described is Lates lakdiva, where 'lakdiva' means coming from Sri Lanka, and Pethiyagoda and Gill propose that this fish should be known as the Sri Lankan Sea Bass in English. This species is described from three fish obtained at the St John’s Fish Market in Colombo, Sri Lanka, in 1994 by the Australian Museum. The three fish measure 220 mm, 239 mm and 256 mm, respectively. The conservation status of Lates lakdiva is extremely uncertain, as the precise origin of the fish is unknown, and large numbers of Lates sp. (i.e. fish in the genus Lates but of uncertain species) have been introduced to estuaries of rivers in Sri Lanka by the fishing industry in recent years.

Specimen of Lates lakadiva. This has been preserved in alcohol since 1994, and its original coloration is unclear. Pethiyagoda & Gill (2012).

The second new species is Lates uwisara, named in honour of U Wisara, a Burmese monk who died as a result of a hunger strike while in prison for protesting against British rule, and who is considered a national hero in Myanmar. It is described from four specimens collected from river estuaries between Yangon and Sittang in 2005 and now in the Australian National Fish Collection at the Commonwealth Scientific and Industrial Research Organisation in Hobart. The four specimens are 353 mm, 363 mm, 332 mm and 350 mm in length, respectively. Pethiyagoda and Gill propose that this fish should be known as the Myanmar Sea Bass in English. Specimens of this fish were also found from fish farms in French Polynesia (where there are no native Lates). Since Lates are also farmed in Myanmar, this raises the possibility that the fish is not native to the areas where it was found.

Specimen of Lates uwisara. This has also lost its original coloration, having been preserved in alcohol since 2005. Pethiyagoda & Gill (2012).

See also New species of Priapiumfish from the Mekong DeltaNew species of Japanese Goby from TaiwanHead-Butting in Giant Bumphead ParrotfishNew species of Sleeper Gobie from the Early Miocene of Otago, New Zealand and Boney Fish on Sciency Thoughts YouTube.

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