The whitefin chimaera (''Chimaera argiloba'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of fish in the family

Chimaeridae The Chimaeridae, or short-nosed chimaeras, are a family of cartilaginous fish. They resemble other chimaeras in general form and habits, but have short, rounded snouts, without the modifications found in related families. Many species have lo ...

. It is found in the Indian Ocean to the NW of Australia, with a restricted distribution. ''Chimaera argiloba'' inhabits marine waters from a depth range of 370–520 m. It is abundant within its range.

Classification/species

The ''Chimaera argiloba'', more commonly known as the Whitefin chimaera, comes from the genus '' Chimaera'', which in Latin translates to 'marine monster'. The species name, ''argiloba'', is in reference to the Greek meaning for 'white', and ''loba'', a Latin word, refers to a 'rounded projection'. This full species name is derived from the unique posterior part of the first dorsal fin, which is both white and rounded, extending outwards.

Differences from other species in ''Chimaera'' genus

The genus ''Chimaera'' includes ten nominal species presented by Carl Linnaeus, which include ''Chimaera obscura'', ''C. cubana'', ''C. panthera'', ''C. fulva'', ''C. lignaria'', ''C. jordani'', ''C. macrospina'', ''C. monstrosa'', ''C. owstoni'', and ''C. phantasma''. ''C. argiloba'' shares the most similarities to ''C. phantasma'', a species most commonly found in the northwestern Pacific. These two species only have slight disparities in morphologies and color. ''C. argiloba'' is different from ''C. panther'' and ''C. owstoni'' in their color schemes and pattern distributions. Where ''C. argiloba'' is uniformly grey-silver, the other two species have a standout dark pattern. Additionally, ''C. lignaria'' have a lavender blue color scheme, and ''C. macrospina'', ''C. fulva'', ''C. jordani'', and ''C. obscura'' all have dark brown exteriors.

Characteristics

The genus ''Chimaera'' is part of the larger family

, which also includes the genus ''

Hydrolagus ''Hydrolagus'' is a genus of fish in the family Chimaeridae found in the Atlantic, Indian and Pacific Oceans.Weigmann, S. (2016)Annotated checklist of the living sharks, batoids and chimaeras (Chondrichthyes) of the world, with a focus on biogeog ...

''. This genus differs from ''Chimaera'' in that these species do not have anal fins. ''Chimaera argiloba'' possess a medium length snout, ranging from 13.7-17.3 cm. From a dorso-ventral view, the snout is narrowly pointed, but is broadly pointed from a lateral point of view. On average, the whitefin chimaera has a horizontal head length of 10.7 cm, and a vertical height of 0.68 times the horizontal head length. In total, ''C. argiloba'' has a body length of 40 cm and a total length of more than 90 cm. Another prominent characteristic is its large gill opening that is separated with a posterior flap that protrudes from the head base, and is interconnected with the back of the gill cover by a short tube. Color-wise, ''C. argiloba'' is grey-silver, both laterally and dorsally. On its ventral side, the color has a slightly paler hue compared to the rest of its body.

Distribution

''Chimaera argiloba'' is most commonly found in northwestern Australia in the Indian Ocean. This particular species does not have a broad distribution, but there have been known findings off the shores of North Caledonia and Indonesia. ''C. argiloba'' reside in waters at a depth of 370 meters, and even going deeper ranging to depths of 520 meters.

Threats

''C. argiloba'' is not widely used for commercial distribution purposes, but is subjected to other minor threats. One arising threat is the capture of this species by fisheries originally set on teleost fish and prawns off the coast of northwestern Australia. Companies such as the North West Slope Trawl Fishery and Commonwealth Western Deepwater Trawl Fishery operate around these areas where the Whitefin chimaera reside. They implement trawl gear that go to depths greater than 300 m, having the potential to inadvertently catch ''C. argioloba''. However, these two fisheries have relatively low activity, and when they do catch these species, the whitefin chimaera are kept alive and usually released back into the waters.

References

{{Taxonbar, from=Q2796172 Chimaera Taxa named by John J. Pogonoski Taxa named by Peter R. Last Taxa named by William Toby White Fish described in 2008