Comprehensive Description

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Description

Colossendeis wilsoni, sp. n. (Text-fig. 2)

 

 

Occurrence. – Station 220, off Cape Adare, 45-50 fathoms; 1 female (Holotype).

 

 

Description. – Trunk very compact; its greatest width, across the first pair of lateral processes, little less than its length; lateral processes in contact except for a slit-like interval between the third and fourth pairs. Ocular tubercle very broad, transversely oval as seen from above, bluntly rounded; eyes dark, andterior pair (or at least their pigmented area) much larger than the posterior. On dorsal surface behind ocular tubercle is a strongly convex area defined posteriorly by a crescentic groove.

 

 

Proboscis decurved, a little longer than trunk, sub-cylindrical, slightly dilated about the middle and again at the tip.

 

 

Abdomen decurved, slightly dialated distally, bluntly rounded at the tip.

 

 

Palp consisting of eight segments only; second segment less than one and a half times as long as fourth; sixth a little longer than fifth or seventh, and about one and a half times as long as thick; eighth about two-thirds as long as seventh.

 

 

Oviger stout; fourth segment a little longer than sixth; spines (very much worn) set in about five rows; terminal claw rather long.

 

 

Legs short and stout, third pair not quite seven times as long as trunk. Femur not quite four times as long as its greatest diameter, slightly shorter than first tibia, which, again, is shorter than second. Tarsus a little shorter than propodus; claw stout and curved, about two-thirds as long as propodus.

 

 

Body and limbs very smooth and free from conspicuous setae.

 

 

Measurements, in mm. –

 

                                                                                          
 

 
 

Holotype.

 
 

Length of proboscis

 
 

6.56

 
 

Greatest diameter of proboscis

 
 

1.84

 
 

Length of trunk

 
 

5.28

 
 

Width across first lateral processes

 
 

4.96

 
 

Length of abdomen

 
 

2.08

 
 

Third right leg (distal segments from fourth) –

 
 

Coxae

 
 

3.75

 
 

Femur

 
 

6.8

 
 

First tibia

 
 

7.2

 
 

Second tibia

 
 

8.56

 
 

Tarsus

 
 

2.8

 
 

Propodus

 
 

3.2

 
 

Claw

 
 

2.08

 
 

Palp –

 
 

Second segment

 
 

2.96

 
 

Third “

 
 

0.64

 
 

Fourth “

 
 

2.08

 
 

Fifth “

 
 

0.8

 
 

Sixth “

 
 

0.96

 
 

Seventh “

 
 

0.72

 
 

Eighth “

 
 

0.48

 
 

 

Remarks. – The most noteworthy character of the specimen described above is the presence of only eight segments in the palp, as compared with the nine that are present in the other species of the genus. The condition of the palps in some specimens of C. lilliei, described below, suggests the possibility that the reduction may be the result of regeneration after injury, but the complete symmetry of the two palps in the present specimen is against this supposition. The relation of the species to Hodgson’s “Notoendeis” has already been alluded to. Apart from the character of the palps, the species is sufficiently distinguished from all other species of the genus by the characters given in the key.

 

 

The species is named in memory of Dr. E. A. Wilson, the chief of the scientific staff of the expedition.” (Calman 1915, p. 18-20)

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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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