Mindeskrift i anledning af hundredaaret for Japetus Steenstrups fødsel / XIV. Gadiculus Argenteus and Gadiculus Thori / 7 (1914) Author: Hector Jungersen, Eugen Warming Table of Contents / Innehåll | << Previous | Next >>
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1905—1910. For this reason I have restricted the comparison to those characters, which are
comparable in both the older and younger stages, especially the number of vertebrae,
and this all the more, because such a character is more precise and exact than the
measurement of the outer characteristics.

In 6 specimens of Gadiculus (adult) from Irish waters, taken by Mr. E. W. L. Holt
and kindly lent me by the Dublin Museum, the following number of vertebrae was found:

        13 + 29, 13 + 29, 13 + 29, 13 + 29, 13 + 29, 13 + 30.

In a specimen from the Skagerak, kindly given me by Dr. A. C. Johansen, the
number was 13 + 29, and in 5 postlarval stages (15—20 mm. long) taken by the “Thor”
in 1905 west of Scotland:

        13 + 29, 13 + 29, 13 + 29, 13 + 29, 13 + 29.

A comparison of the number of vertebrae in the northern and southern Gadiculus
(20 chance specimens of each) gave the following result:

northern species (G. Thori)		southern species (G. argenteus)
(west of Scotland)		(Mediterranean)
No. of vert.	No. of spec.	No. of vert.	No. of spec.
43	3	41	3
42	16	40	14
41	1	39	3

We see, therefore, that there is on an average over 2 vertebrae more in the northern
than in the southern species, a very considerable difference on such a low number of
vertebrae as is here in question. The number of fin-rays in D³ and A² was also on an
average several rays higher in the northern than in the southern species, but in this
species the rays are difficult to count with absolute accuracy, for which reason I shall not
give the detailed numbers at present.

The conclusion from the above is, that such great differences exist between
specimens of Gadiculus from the Mediterranean ami the Atlantic west of the British Isles
(and the Skagerak), that they must be regarded as belonging to 2 different species,
distinguishable by exact tad reliable characters.

The species living in the Mediterranean, which was deacribed first by Guichenot
under the name Gadiculus argenteus, must retain that name. For the North Atlantic
species I propose the name Gadiculus Thori nov. num. in memory of the Danish
searchvessel “Thor”, on the cruises of which the post larval developmental history of both
species has been cleared up.

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