400 PROCEEDINGS OF THE NATIONAL AIUSEUM vol. 99 



KEY TO THE SPECIES OF PARANTHESSIUS 

 (Based on characters of females) 



1. Armature of terminal endopodite segment of fourth leg consisting of 2 



spines or setae or a spine and a seta 2 



Armature of this segment consisting of 3 spines or 2 spines and a seta 10 



Armature of this segment consisting of 4 spines or setae 12 



Armature of this segment consisting of 5 spines or setae 13 



2. Terminal antennal segment bearing heavy prehensile claw 3 



Terminal antennal segment without usual Iieavy claw, bearing instead 



3 jointed setae of about equal size parvus (Norman and Scott) 



3. Caudal rami 2 or more times as long as wide 4 



Caudal rami no more than one and one-half times as long as wide. 



validus (Sars) 



4. Rostrum a strongly curved, posteriorly directed, heavily chitinized 



beak 5 



Rostrum replaced by a gently curved, short prominence accompanied 

 by a bifurcate, weakly chitinized accessory structure, 



perplexus, new species 



5. Fifth leg the usual slightly modified cylinder, or with base expanded 6 



Fifth leg characteristically shaped: in outline an inverse truncated 



cone, the squared-off terminal surface about twice as wide as base. 



cynthiae (Brian) 



6. Length of longest antennal segment much more than twice width 7 



Length of longest antennal segment less than twice width pectinis (Pesta) 



7. Margins of fifth leg roughly parallel 8 



Free segment of fifth leg expanded basally 9 



8. Ventral surface of last abdominal somite with a pair of rows of long 



slender spinules columbiae (Thompson) 



No ornamentation on last abdominal somite rostratus (Canu) 



9. Lateral margin of terminal segment of fourth endopodite bearing 2 



spinous processes tivelae, new species 



Lateral margin of this segment without processes saxidomi, new species 



10. Second segment of fourth endopodite with a single seta 11 



Second segment of fourth endopodite bears 2 setae on medial surface. 



anemoniae Claus 



11. Terminal segment of fourth endopodite with 3 spines panopeae, new species 



Terminal segment of fourth endopodite with 2 spines and a ciliated seta. 



nasutum (Edwards) 



12. Length of caudal rami twice width robustus (Thompson and Scott) 



Length of caudal rami at least 4 times width. 



serendibicus (Thompson and Scott) 



13. Terminal antennal segment longer than penultimate segment 14 



Terminal antennal segment much smaller tlian penultimate. 



prehensilis (Sars) 



14. Third antennal segment bearing only setae 15 



Third antennal segment with a heavy spine on the distal ectal corner. 



propinquus NichoUs 



15. Length of caudal rami 4 times width finmarchicus (Scott) 



Length of caudal rami 10 times width tenuicaudis ( Sars) 



PARANTHESSIUS ANEMONIAE Claus, 1889 



Paranthessius anemoniae Claus, 1889, p. 343, figs. 8-15 (Trieste; host: Anemojiia 

 sp.).— Canu, 1894, p. 137 (lies Chausey, France) ; 1898, pp. 413-415, pi. 10.— 

 ZULUETA, 1912, p. 12.— MONOD and Dollfus, 1932, pp. 143, 145-146. 



