IUCN threat status:

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Comprehensive Description

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Description

Austrodecus glaciale

 

(Plate VIII., fig. 1.)

 

 

Specific characters: --

 

 

Body stout, segmented, with lateral processes close together.

 

Proboscis long, tapering and curved near the extremity.

 

Chelifori absent.

 

Palps 6-jointed; terminal joint articulated to one side of the penultimate.

 

Ovigers 6-jointed?

 

Legs short, first coxae armed dorsally with two spurs.

 

Abdomen long and slender.

 

 

This is a diminutive species; the entire animal does not cover a space 8 mm. square.

 

 

The trunk is stout and distinctly segmented; the lateral processes are not widely separated, but as they are rather short and tapering, the intervals at their distal extremities are very pronounced. The first coxae, which are the largest, all bear dorsally a pair of stout tubercular spines which are very prominent. Each of the four segments of the trunk bears a stout tubercle of some elevation in the middle line, and close to its posterior border.

 

 

The Cephalon is scarcely expanded, and almost fills the interval between the first pair of lateral processes and their first coxae. Anteriorly it bears a very long Ocular tubercle which is directed obliquely forwards, flask-shaped and truncated at its extremity, on the upper surface of which, in a compact group, are four very well-developed eyes.

 

 

From the truncated end of the trunk the Abdomen projects horizontally; it is rather long and not separated by an articulation. On the ventral surface of the trunk a slightly raised band passes transversely between the first three pairs of lateral processes, with the last pair the band is interrupted in the middle line.

 

 

The Proboscis is long and of a peculiar shape, not unlike the snout of a weevil beetle. It is movably articulated to the body, and for about one-third of its length it is not disproportionately slender, then it tapers rather rapidly to a long and very slender structure, curved downwards near the tip. It is quite smooth and presents an annular appearance which is less distinct proximally.

 

 

The Chelifori are quite absent.

 

 

The Palps are six-jointed and arise above but well to the side of the proboscis (fig. 1b). The first joint is short and very stout, the second is long and extends beyond the extremity of the ocular tubercle. The third is very short and its distal limit indistinct. The fourth joint is rather more than half the length of the second. The second joint bears the stumps of several spinous setae along its length; on the fourth joint a similar number of curved spinous setae occur, and these increase in size to the distal extremity of the joint, which also bears a few finer setae and a small distal fringe. The last two are quite small and rather densely clothed with small setae. The last one is articulated to one side, and not at the end, of the penultimate, and the setae occur mainly on the outer side.

 

 

The Ovigers arise ventro-laterally, close to the angel formed by the cephalon and the first lateral process. They are extremely small, and it is open to question whether they are mature or not. As the removal of one of these appendages involves serious risk to the only specimen, it cannot be very satisfactorily described. Not less than six joints can be distinguished, the first three of which are very small. A small body-process from which the appendage arises may be an additional joint. The terminal joint is the longest, it is rounded at the extremity and does not carry any trace of a claw, nor are setae of any kind discernible.

 

 

With regard to the Legs, the first coxa has already been alluded to as the larges of the three, the other two are very little if any shorter, and the second is dilated distally. It is difficult to get the limb in one plane for measurement, and the joints appear subject to some variation. The proportion of the joints appears to be 3.5 : 3 : 2.5 : 0.5 : 2.5. The femur is stout, and the two following joints decrease in caliber. The limb bears a very scattered setae, most numerous on the second tibia. The tarsus is very small and cup-like, with two or three spinous setae ventrally; the propodus is proportionately long, slightly curved, and bearing a few setwe. Of its ventral margin it carries a row of setae, but there is nothing very distinctive about them. The claw is short and stout, and is accompanied by two slender auxiliaries.

 

 

The only example of this peculiar species is a female, and the Genital aperatures are found in the middle of the second coxae of all the legs.

 

 

Taken by the dredge in Winter Quarters before the ship was frozen in. Ten fathoms or less.” (Hodgson 1907, p.53-54)

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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