236 



Pereon somites II-VII and pleon somites I-III have backwardly 

 directed, acute, and smooth dorsal denticles. The posterior lower angle 

 of coxal plate V is stretched into a long acute denticle. 



The head has long lateral spines. The eyes are small. Antennae I are 

 equal in length to the pereon and pleon together; the outer margin of the 

 flagellum is armed with strong spines and the inner margin with setae; 

 in males the proximal part of the inner margin bulges so that a plate 

 is formed at the base of the flagellum; the plate has long sensory setae 

 along its margins. 



The lobes of maxillae II are proximally fused and bear two spines on 

 the upper distal angle and one on the lower distal angle. The protopodite 

 of the maxillipeds is almost rectangular, its breadth in the middle part 

 2/3 its length; the outer lobes have the form of narrow triangular plates 

 attached to the outer angles of the distal margin of the protopodite; the 

 distal margin of the lobes is rounded and armed with three spines. 



Pereopods I and II are thin and simple; their 4th segment is very 

 short and equal to the 3rd; the 5th segment of pereopods I is 1.5 times 

 and of pereopods II only slightly longer than the 6th segment; the claws 

 of both pairs are moderately long and almost straight. The 4th and 6th 

 segments of pereopods III and IV are roughly equal and each of them 

 somewhat shorter than the 5th; the claws are small and almost straight. 



196 Pereopods V are longer than the remaining pairs; the rod-shaped 2nd 

 segment has 4-5 long straight spines on its anterior margin and 6-7 on 

 its posterior margin; the distal process is thin and acute; the 4th, 5th, and 

 6th segments are fused; the claw is very small and thin. Pereopods VI 

 are shorter than pereopods V; the length ratios of the 2nd, 4th, 5th, and 

 6th segments are 20 : 10 : 14.5 : 16; the claw is small and curved. 

 Pereopods VII are somewhat longer than pereopods VI and have the 

 same proportions; the claw is straighter. 



The uropods are thin and rod-shaped. The telson is spatulate and 

 distally broadened. 



Distribution: Atlantic Ocean from 61° N to 28-39° S, tropical 

 regions of the Indian Ocean, southern tropical regions of the Pacific 

 Ocean at New Caledonia and New Zealand. Most records are confined 

 to the tropical regions. A. acanthodes lives in the near-surface layers to 

 a depth of 200-500 m. 



197 2. Acanthoscina birsteini Vinogradov, 1976 (Fig. 100) 



Vinogradov, 1976: 130. 



Size of sexually mature female 7 mm. 



Pereon somites II-VII have dorsal, backwardly directed denticles 

 which are particularly large on somites VI and VII; the pleon somites 

 have shorter denticles. The head has small lateral spines. The eyes are 

 not noticeable. 



