357 



Distribution: All specimens (three females) were found in a catch 

 taken at a depth of 0-100 m in the central part of the Pacific Ocean 

 (22° N, 114° W). 



6. Genus Parathemisto Boeck, 1870 



Boeck, 1870: 87; Bovallius, 1889: 248; Barnard, 1930: 419; Bowman, 

 1960: l>AA.—Themisto Guerin, 1825: 772; Stephensen, 1923: 19; 

 1924: 94. ^Euthemisto Bovallius, 1887a: 21; 1889: 275. 



The body is elongated and laterally compressed. All the somites 

 of the pereon are free. The head is large and round, its height 

 exceeding its length. The eyes occupy the entire dorsolateral surface 

 of the head. In antennae I the flagellum has a long narrowly conical 

 segment.Antennae II have few segments and are about the same length 

 as antennae I. The mandibles in both sexes bear a palp and a strong 

 dentate process. The outer lobe of maxillae I has two strong apical spines. 

 The inner lobes of the maxillipeds are well developed. Pereopods I are 

 simple. Pereopods II have a chela formed by the 6th segment and the 

 narrow grooved process of the 5th segment. In pereopods III and FV the 

 5th segment is broadened and together with the 6th segment forms an 

 indistinct subchela. Pereopods V-VII are longer than pereopods III-IV. 



Type species: Parathemisto abyssorum Boeck, 1870. 



Boeck (1870) separated Parathemisto from the genus Themisto 

 Guerin on the basis of the approximately equal length of the 

 pereopods V-VII; in Themisto pereopods V are significantly longer than 

 pairs VI or VII. Subsequendy, Bovallius (1887a) noted that the name 

 Themisto was already occupied and accordingly renamed the genus 

 Themisto as Euthemisto. Stephensen (1924) showed that the differences 

 between the genera, as listed by Boeck, are not significant since based on 

 the ratio length of the legs, the male of some species could be related to 

 the genus Euthemisto but the female to the genus Parathemisto. Barnard 

 (1930) and subsequent authors considered Parathemisto and Euthemisto 

 subgenera of the single genus Parathemisto. 



The following features are characteristic of the subgenus Parath- 

 emisto: absence of dorsal denticles on the somites of the pereon and the 

 pleon, thil aid straight flagellum of antennae I in females, just slightly 

 broadened 5th segment of pereopods III and IV, and highly stretched 

 inner distal angle of the basipodite of uropods III. 



In representatives of the subgenus Euthemisto, dorsal denticles may 

 be present on the somites of the pereon or the pleon; the flagellum of 

 antennae I in females is generally strongly curved and more massive than 

 in Parathemisto (with the exception of P. {E. libellula); the 5th segment 

 of pereopods III and IV is highly broadened; pereopods V are generally 



