359 



1. Parathemisto (Parathemisto) abyssorum Boeck, 1870 (Figs. 149, 

 150) 



Boeck, 1870: 87; Sars, 1883: 75; Bovallius, 1887c: 566; Stephensen 

 1923: 20 (Themisto); 1924: 95; Schellenberg, 1927: 629; Barnard, 1959: 

 125; Bowman, 1960: 36^.—oblivia Bovallius, 1889: 251; Sars, 1895: 

 10; Vosseler, 1901: 80. 



Length of sexually mature specimens 10-21 mm. 



The head is equal in length to the first two somites of the pereon. 

 In antennae I the peduncle is three-segmented and short; the flagellum 

 in females is just barely longer than the head, narrowly conical, and not 

 distinctly divided into segments; in sexually mature males the flagellum 

 consists of 13-15 segments and extends to the end of the pereon. 



The mandibles have a narrow denticulate cutting edge and an acces- 

 sory plate is present in the left mandible; the dentate process is strong and 

 broad; the 2nd segment of the thin palp is approximately twice longer 

 than the 1st and 1.5 times the 3rd segment. The outer lobe of maxillae I 

 bears a row of setae in addition to two strong apical spines and the palp 

 is broader than long. The outer lobe of maxillae II is narrow and apically 

 armed with two spines; the much broader inner lobe bears only one api- 

 cal spine. The outer lobes of the maxillipeds are narrow, sickle-shaped, 

 and unarmed along the convex outer margin; the inner lobes form a plate 

 with a straight or concave distal margin; the basal plate is unarmed. 



The 6th segment of pereopods I is shorter than the 5th and its pos- 

 terior margin very finely denticulate with a few submarginal short setae; 

 the claw bears a group of short setae in the proximal part of the inner 

 margin. Pereopods II are somewhat longer than pereopods I; the 5th seg- 

 ment has a spoon-shaped process extending to 2/3 the length of the 6th 



Fig. 149. Parathemisto (Parathemisto) abyssorum Boeck, female (after Barnard, 1959). 



