THE BREEDING OF THE NORTH ATLANTIC FRESHWATER-EELS
139
11. AnguiUa anghilla L.-A. rostrata LE SUEUR
THE TAXONOMIC SITUATION
Ege (1939) has shown that the two species are more closely allied in
every respect than either is even to A . japonica Temminck and Schlegcl,
which is quite closely related to both. The two Atlantic species are
most easily distinguished by thc number oi vertebrae. Schmidt (1913)
examined sixteen samples between Iceland and Cyprus, altogether
2775 specimens of A . anguilla, and found from 110 to 119 vertebrae,
average 114-7, only one having 110 and seventeen 111 vertebrae.
Furthermore in four samples of A . rostrata between St. Laurence and
St. Croix, J7irgin Is., 361 specimens had vertebral complements varying
between 103 and 110, average 107.1 vertebrae; twelve had 110 vertebrae. Later on Schmidt (1916, p. 6) and Ege (1939) added further
material of A . rostrata, so that 962 specimens have been examined,
showing a variation of from 103 to 111 vertebrae, average 107.2: thirtythree had 110 and three had 11 1 vertebrae.
The differences in the average numbers of fin rays and branchiostegals are too small to be useful in identification. While Schmidt was
fully aware of the fact that the numbers of vertebrae and fin rays may
vary to a certain extent under the influence of the environment, this
has not been shown €or one character, the dentition, which Schmidt
also used. Ege (1939, p. 122) has studied the proportion between the
length of the intermaxillary-vomerine band from the foremost point to
the hindmost tip, and the length from the same foremost point to the
posterior end of the right maxillary band. This character varies to a
certain extent according to sex and the total length of the fish. Out of
Ege’s detailed analysis we may select a5 an example the females of a
length between 30 and 40 cm. The percentage values are, for A .
japonicu 77-7, A . rostrata 69.0 and A . anguilla 76.1.
When Schmidt (1927, 1928) divided A . australis Richardson into
two subspecies he had a similar case, later studied in detail by Ege
(1939). Here the total number of vertebrae is 112.6 in A . australis
australis and 111.7 in A . austraZis schmidti. Using the same character
of the dentition (Ege, 1939, p. 184) as above for A . anguilla and A .
rostrata, corresponding values of specimens measuring 50-60 cm are
69.3 and 71.2, thus indicating a much smaller difference, if any, than
that between A . rostrata and A . anguilla.
Tucker treats A . anguilla and A . rostrata as though they are distinguished only by the number of vertebrae. It ahould, however, not;
be forgotten that Johs. Schmidt made a closc study of the taxonomy of
the genus Anguilln Shaw. This was brought together in a monograph
139
11. AnguiUa anghilla L.-A. rostrata LE SUEUR
THE TAXONOMIC SITUATION
Ege (1939) has shown that the two species are more closely allied in
every respect than either is even to A . japonica Temminck and Schlegcl,
which is quite closely related to both. The two Atlantic species are
most easily distinguished by thc number oi vertebrae. Schmidt (1913)
examined sixteen samples between Iceland and Cyprus, altogether
2775 specimens of A . anguilla, and found from 110 to 119 vertebrae,
average 114-7, only one having 110 and seventeen 111 vertebrae.
Furthermore in four samples of A . rostrata between St. Laurence and
St. Croix, J7irgin Is., 361 specimens had vertebral complements varying
between 103 and 110, average 107.1 vertebrae; twelve had 110 vertebrae. Later on Schmidt (1916, p. 6) and Ege (1939) added further
material of A . rostrata, so that 962 specimens have been examined,
showing a variation of from 103 to 111 vertebrae, average 107.2: thirtythree had 110 and three had 11 1 vertebrae.
The differences in the average numbers of fin rays and branchiostegals are too small to be useful in identification. While Schmidt was
fully aware of the fact that the numbers of vertebrae and fin rays may
vary to a certain extent under the influence of the environment, this
has not been shown €or one character, the dentition, which Schmidt
also used. Ege (1939, p. 122) has studied the proportion between the
length of the intermaxillary-vomerine band from the foremost point to
the hindmost tip, and the length from the same foremost point to the
posterior end of the right maxillary band. This character varies to a
certain extent according to sex and the total length of the fish. Out of
Ege’s detailed analysis we may select a5 an example the females of a
length between 30 and 40 cm. The percentage values are, for A .
japonicu 77-7, A . rostrata 69.0 and A . anguilla 76.1.
When Schmidt (1927, 1928) divided A . australis Richardson into
two subspecies he had a similar case, later studied in detail by Ege
(1939). Here the total number of vertebrae is 112.6 in A . australis
australis and 111.7 in A . austraZis schmidti. Using the same character
of the dentition (Ege, 1939, p. 184) as above for A . anguilla and A .
rostrata, corresponding values of specimens measuring 50-60 cm are
69.3 and 71.2, thus indicating a much smaller difference, if any, than
that between A . rostrata and A . anguilla.
Tucker treats A . anguilla and A . rostrata as though they are distinguished only by the number of vertebrae. It ahould, however, not;
be forgotten that Johs. Schmidt made a closc study of the taxonomy of
the genus Anguilln Shaw. This was brought together in a monograph