CHIGGERS — ^FARRELL -125 



appear to have folded over the posterior portion of the scutum, 

 occasionally over the lateral margins. 



Key to species of Euschongastia of North America 



1. Tibiala III present 2 



No tibiala III 14 



2. No subterminala or parasubterminala I {"lacerta" group) 3 



Subterminala and parasubterminala I present 4 



3. One genuala I; microspur I distal to spur 1. E. lacerta Brennan 



Two genualae I; microspur I proximal to spur. 



2. E. bi genuala, new species 



4. Palpal claw with two prongs; a mastitarsala III present. 



3. E. nunezi (Hoffmann) 

 Papal claw with more than two prongs; no mastitarsala III 5 



5. Palpal claw with more than three prongs; sensillae elongate-clavate, 



joining with pedicels in gradual taper 6 



Palpal claw with three prongs; sensillae capitate or subcapitate, heads 

 more abruptly distinct from pedicels 9 



6. Three genualae I 4. E. trigenuala, new species 



Two genualae I 7 



7. One pair of eyes, or corneas indistinct or lacking; galeal seta nude. 



5. E. pipistrelli Brennan 

 Two pairs of eyes, corneas distinct; galeal seta branched 8 



8. Lateral seta on palpal tibia branched 6. E. oregonensis (E^ving) 



Lateral seta on palpal tibia nude 7. E. samboni (Radford) 



9. Scutum with only two crescentic ridges, one anterior to each pseudo- 



stigma 10 



Scutum with three joined ridges, one anterior to each pseudostigma and 

 a third extending from the apexes of these anteriorly around the 

 anterior median seta ("rubra" group) 11 



10. Ventral setal formula begins 2-2 8. E. peromysci (Ewing) 



Ventral setal formula begins 2-4 9. E. cordiremus Brennan 



11. Lateral seta on palpal tibia pectinate; anterior and posterior dorsal 



setae similar 12 



Lateral seta on palpal tibia usually nude; anterior dorsal setae with 

 numerous long setules, posterior dorsal setae with fewer, scalelike 

 setules {E. diversa, new species) 13 



12. Scutum smaller, PW less than 67 microns; range southern. 



10. E. rubra, new species 

 Scutum larger, PW about 77 microns; range northern. 



11. E. magna, new species 



13. Palpal claw shorter, branching on proximal half, accessory prongs inter- 



rupting contour of claw 12a. E. diversa diversa, new subspecies 



Palpal claw longer, branching on distal half, accessory prongs lying close. 



12b. E. diversa acuta, new subspecies 



14. Palpal claw with three prongs 15 



Palpal claw with more than three prongs 19 



15. Two setae on coxa III 13. E. guntheri (Radford) 



One seta on coxa III 16 



