“Thaumeledone gunteri, n.sp. (Pl. IV, fig. 3)
St. 158. 21. i. 27. 53º 48’ 30” S, 35º 57’ 06” W. 401-411 m., rock. Large dredge: one ♀ (Brit. Mus. 2) [Type]
Dimensions (in mm.).
Dorsal mantle, length … … 36
Head, width, % mantle length … 86
Mantle, width, % mantle length … 111
Arms, % total length … … 57
Suckers, diameter, % mantle length 8.3
Web, index … … … 60
The body is globular, and the head distinctly narrower than the body. It is, however, rather broader than is usual in charcoti. The eyes are distinctly larger than in most examples of the latter. The arms (see above) are very short for an adult Octopod, being amongst the shortest recorded. The suckers are small and close set. The sectors of the web are, I think, subequal, C and D being slightly deeper than the others. The web is very large, and attains the great depth of 60 per cent of the arms. The surface is rather a rich, light purple dorsally, becoming paler ventrally. It is covered dorsally and laterally by a number of close-set warts. These are very curious, and confer on the animal a rather mossy appearance. On the sides of the web and on the arms they tend to be circular and bubble-like. On the anterior surface of the web, head and body, they are branched and irregular, and it is here that they are seen to stand out very clean-cut from the surface. They remind of the similarly clean-cut warts in Octopus pallida, though are not stellate in gunteri. It is possible that they may be like those of a form of charcoti. Joubin (1906, p. 6) says that in the latter some of the warts are probably branched. From the figure (loc. cit. pl. i, figs. 1-2) it is quite evident that, in charcoti, the warts on the head and body are in close contact with each other, while in gunteri they are quite separate. In Joubin’s later figure (1914[?], p. 36) and in one of the ‘Terra Nova’ specimens the warts are quite separate but, in the former, they are granular, and in the latter, they are mammiform, both very unlike those in gunteri.
The funnel is short, narrow and pointed. The funnel-organ is VV-shaped. The limbs are rather slender and pointed at each end. They remind one of those of E. “aurorae” (Berry, 1917, fig. 14). There are five to six filaments in each demibranch, a very low number. The ink sac is absent. The radula is degenerate and represented by a simple unicuspid rhachidian, the mesocone of which is low and stout. There are faint traces of admedian teeth and of an oblong second lateral with a low cusp.
REMARKS. This species has a superficial resemblance to E. charcoti. For a long time I considered that it should be treated as a well-marked sub-species of the latter, especially since only a single specimen is available, and that a female. The profound differences in radula, etc., were then discovered. The degeneration of the radula and loss of the ink sac, length of arms, depth of the web, number of gill filaments, the sculpture and, in a less degree, the shape of the funnel-organ components and head, form a highly peculiar and characteristic assemblage.
Upon examination of other species of Eledone from adjacent seas I find that E. brevis, Hoyle (1886), has a degrenerate radula of the same type as gunteri. It is also devoid of an ink sac. Though quite distinct specifically, I consider that these two interesting forms are congeneric.”
(Robson, 1930: 392-394)
Thaumeledone gunteri is a species of small, benthic, deep-sea octopus found in the bathyal zone in the Southern Ocean near South Georgia.[1]
The mantle length of Thaumeledone gunteri is typically about 5 cm (2.0 in) and the total length is 10 cm (3.9 in), the arms being relatively short at 5 cm. The background colour is whitish, but the dorsal and ventral surfaces are covered by large, irregular, deep purple tubercles. The web linking the arms is uniformly pale. The head is narrower than the mantle, with several large tubercles above the eye. The eight arms are joined by a deep web, with about 35 small suckers on each arm. The funnel organ is "VV"-shaped and there are five elements in the radula. The posterior salivary gland, a diagnostic feature in this genus, has a diameter of 11 mm.[2]
The funnel organ in T. gunteri is similar to that in Thaumeledone peninsulae and they both share a characteristic loop in the rectum. Thaumeledone rotunda is a circumpolar species found at greater depths and has several morphological features differing from the other two species. Despite this, a phylogenetic study undertaken in 2008 of the molecular relationships in the genus, determined that T. gunteri and T. rotunda are sister taxa and that T. peninsulae is more distantly related.[3]
T. gunteri is found in the far south Atlantic Ocean in an area around South Georgia, including the Shag Rocks, ranging from 53°S to 55°S and 39°W to 35°W.[4] It has been caught by trawling at depths of 364–964 m (1,194–3,163 ft), but may well occur at greater depths, as these waters are relatively underexplored.[2]
Thaumeledone gunteri is a species of small, benthic, deep-sea octopus found in the bathyal zone in the Southern Ocean near South Georgia.
Thaumeledone gunteri is een soort in de taxonomische indeling van de inktvissen, een klasse dieren die tot de stam der weekdieren (Mollusca) behoort. De inktvis komt enkel in zout water voor en is in staat om van kleur te veranderen. Hij beweegt zich voort door water in zijn mantel te pompen en het er via de sifon weer krachtig uit te persen. De inktvis is een carnivoor en zijn voedsel bestaat voornamelijk uit vis, krabben, kreeften en weekdieren die ze met de zuignappen op hun grijparmen vangen.
De inktvis komt uit het geslacht Thaumeledone en behoort tot de familie Octopodidae. Thaumeledone gunteri werd in 1930 beschreven door Robson.[1]
Bronnen, noten en/of referenties
