Every year, thousands of new species are discovered and described, though media very rarely talks about them. Because for non-specialists, differences between species are not always obvious: a fly is a fly, a fish is a fish… But there is the small difference which shows it is something new. Each discovery has its own story. Some of them are more original than others, in spite of quasi null media interest.
This article presents how a species of « snailfish » was discovered off the Kerguelen and Crozet Islands: the oblique mouth snail fish or Paraliparis obliquosus.
During each austral summer, fishing campaigns of toothfish (Dissostichus eleginoides) take place off the Kerguelen and Crozet Islands (Austral Ocean). More than 5000 tons of fish are collected every year. Fisheries are controled by the Terres Australes et Antarctiques Françaises (TAAF). Thus to provide the monitoring of toothfish stocks in their environment, each capture is measured, weighed, sexed and the stomacal content observed. Toothfish are large predator fishs (70 cm on average for a maximal length exceeding 2 meters; Fig. 1). They feed mainly on shellfishes and fishes.
The 3rd of October 1999, the « Cap Kersaint » longliner caught off the Crozet Islands a toothfish whose stomacal content revealed the presence of a fish about 10 cm long, unknown from the crew members. It was in a bad state, in two separate pieces, with the skin, the tail and the eyes missing. This specimen was sent to the Muséum National d’Histoire Naturelle (MNHN) for identification.
During this same period, a scientific campaign (ICHTYOKER cruise) was undertaken in the Kerguelen archipelago to study the impact of predators like penguins and otaries on pelagic fishes populations. The 5th of December 1999, what appeared to be a juvenile snail fish was caught and also sent to the MNHN.
Liparids, or snailfishes, are stocky fishes, covered by a gelatinous gangue, with a very high morphological diversity. They are encountered in all oceans of the world, but they are difficult to collect. Little is known about their biology and their life habits. Nevertheless above 300 species are nowadays known. And at almost each scientific campaign of prospecting, some new species are discovered.
In 2002, Professor Guy Duhamel (MNHN) and Doctor Natalia Chernova (Zoological Institute Russian Academy of Sciences of St-Petersburg), specialised in liparids, looked at these two specimens. Using fins, mouth and skeleton structure, they concluded those two individuals belong to a same new species, Paraliparis obliquosus or oblique mouth snail fish. The damaged specimen has allowed to describe the head, and the juvenile, the rest of the body (Fig. 2).
Figure 2 : Rebuilding of an adult individual belonging to the Paraliparis obliquosus species. Chernova and Duhamel (2003)
It is a stocky fish of small length (about 10 cm), whose head and body are covered by a gelatinous gangue. The skin is blackish, and the oral and gill cavities as well as the peritoneum are black. The pectoral fins are large and divided in two parts; the inferior lobe reaches the jugular region. There is no pelvic fin. The sensorial pores are well distinguishable on the head. The oral opening is oblique. Gill openings are not large but reach to the level of the third and fourth ray of the pectoral fins. Finally, this species has only five rays in its caudal fin.
The family Liparidae is just like the Austral Ocean: very little is known about it. And by making more faunistic inventory programs with sufficient means, lots of other secrets will be revealed to us.
Chernova N.V. & G. Duhamel (2003). A new species and additional records of Paraliparis (Scorpaeniformes: Liparidae) from the Southern Ocean with a provisional field key to juveniles
Nouvelle espèce et nouveaux signalements de Paraliparis (Scorpaeniformes: Liparidae) de l’océan Austral, et clé provisoire pour identifier les juvéniles. Cybium 27(2), p 137-151. http://www.mnhn.fr/sfi/cybium/numeros/french/272/10.sumchernova.html
Add new comment