384 



for specimens from the Pacific versus the Atlantic Ocean, the number of 

 fused somites of the pereon also changes with age. In embryonal forms 

 (from the brood chamber of females) all the somites of the pereon are 

 free. According to Laval (1968a), in larvae which have just changed over 

 to a free mode of life and at subsequent larval stages, somites I-V are 

 fused. In females with rudimentary oostegites, somites I-IV are fused 

 but in sexually mature females, somites I-III. In young males with an as 

 yet unsegmented flagellum of the antennae, somites I-IV are fused but in 

 sexually mature males, only somites I-II. As shown by Laval, the post- 

 larval development of L. schizongeneios generally includes eight stages 

 in males and six stages in females; however, the number of stages may 

 vary. The entire cycle of development up to an adult animal takes less 

 than three months in tropical waters, but at much lower temperatures is 

 significantly retarded. 



Distribution: A circumtropical species. Tropical and warm-water 

 regions of the Atlantic Ocean from 47° N to 45° S, the Mediterranean 



313 Sea, the Indian Ocean, and tropical and subtropical regions of the Pacific 

 Ocean. It inhabits the upper 200 m layer. It is found everywhere on the 

 Leptomedusae Phialidium and the juvenilles(~ 2 mm) specimens some- 

 times on Syphonophozae Lensia. 



2. Lestrigonus shoemakeri Bowman, 1973 (Fig. 163) 



Bowman, 1973: 43. 



Length of sexually mature males 3.5-4.0 mm, of females 

 2.3-2.7 mm. 



The length of the head is less than half its height and 1/3 the length of 

 the pereon. In females somites I-IV of the pereon are fused, but furrows 

 remain between them in the dorsal part; somites I and II are fused in 

 males. 



The antennal gland (lateral view) covers the epistome but does not 

 extend to the lower margin of the mouth cone. The mandibles bear 

 eight-nine denticles on the cutting edge and seven-eight denticles on 

 the accessory plate. The outer lobe of maxillae II has two terminal and 

 one subterminal spine and the inner lobe has a short terminal spine. The 

 outer lobes of the maxillipeds are conical and have five submarginal and 

 two terminal spinules. 



The 2nd segment of pereopods I has a humped anterior margin; 

 the distal process of the 5th segment bears five-six spines; the 6th seg- 

 ment has a spine in the distal part of the anterior margin. The distal 

 process of the 5th segment of pereopods II exceeds half the length of 

 the 6th segment; the latter has one-two spines on the anterior margin. 



314 Pereopods III-IV are comparatively thin; the 5th segment bears two and 

 the 4th one spine on the posterior margin. The 2nd segment of pere- 

 opods V-VII is distally broadened; In pereopods VI-VII very distinct 



