COPEPODA FROM IFALUK ATOLL 79 



Key to the Species of Harpacticus 



FEMALES 



1. Furcal rami 1)4 times or more longer than wide 2 



Furcal rami as long as wide or wider than long 3 



2. Furca IH times as long as wide; basis of maxillipede convex on both sides, 



twice as long as wide. 2nd segment of endopodite leg 4 with 1 seta. 



H. furcatus Lang 



Furoa more than twice as long as wide; basis of maxillipede only slightly 



convex on external border, internal border straight, 3 times as long as 



wide. 2nd segment endopodite leg 4 with 2 setae. . H. furcifer Giesbrecht 



3. Basis of maxillipede with straight or convex internal border 4 



Basis of maxillipede with concave internal border or margin deeply incised 



to form a square notch 5 



4. 2nd segment of endopodite leg 2 with 2 internal setae. 



H. superflexus Willey 

 2nd segment of endopodite leg 2 with 1 internal setae. 



H. flexus Brady and Robertson 



5. Antenna with pectinate spines 6 



Spines of antenna normally developed 7 



6. Total number of appendages on terminal exopodal segment of legs 2 to 4 



is 7, 8, and 8, respectively H. pulvinatus Brady 



Setae on terminal exopodal segment of legs 2 to 4 number 6, 7, and 8, 

 respectively H. compsonyx Monard 



7. Baso-endopodite with 3 spines or setae 8 



Baso-endopodite with 4 or 5 spines or setae, one of which may be 



small 12 



8. Expedite of leg 5 with 4 setae H. glaber Brady 



Exopodite with 5 setae 9 



9. Median seta of baso-endopodite leg 5 spinulose . . H.confusus, new species 

 Median seta of baso-endopodite leg 5 normally developed 10 



10. Terminal segment of exopodite leg 1 with 3 claws, no seta present. 



H. chelifer (O. F. Miiller) 

 Terminal segment of exopodite leg 1 with 3 or 4 claws and a seta .... 11 



11. Terminal segment of exopodite leg 1 with 3 claws and 1 seta. 



H. trisetosus Lang 

 Terminal segment of exopodite leg 1 with 4 claws and 1 seta. 



H. gurneyi Jakubisiak 



12. Baso-endopodite of leg 5 with 5 spiniform setae. 



H. meridionalis G. O. Sars 

 Baso-endopodite of leg 5 with 4 spiniform setae 13 



13. External spine on baso-endopodite of leg 5 very small, % the length of 



exopodite H. islandicus Klie 



External spine on baso-endopodite of leg 5 as long as exopodite of leg 5 or 

 slightly shorter 14 



14. Baso-endopodite of leg 5 with a transversal row of spinules. 



H. uniremis Kr0yer 

 No row of spinules on baso-endopodite of leg 5 15 



15. On terminal segment of endopodite leg 1 there are, in addition to claws, 



some small spines, one of which points upward . . H. nicaeensis Glaus 



In addition to claws on terminal segment of endopodite leg 1 there are 



some spinules or hairs, none of which points upward 16 



