Mesostigmata 53 



their respective families, but those with only two tines are more 

 difficult. 



Gamasids can be recognized readily in the males because the che- 

 licerae are more or less modified to function in the transfer of sper- 

 matophores to the females and the male opening is anterior to the 

 sternal plate. The females are recognized by the characteristic arrange- 

 ment of the ventral plates as described by Tragardh 1946. The lateral 

 plates are absent, and the metasternal plates are either free and fused 

 with the corresponding endopodal plates, or small, or fused with the 

 sternal plate. The epigynial plate bears a pair of setae and it may or 

 may not be fused with the ventral plate. 



Key to the Gamasides 



1. Lacking large bell- or bucket-shaped suckers at sides of anal open- 

 ing 2 



With large bell- or bucket-shaped suckers at sides of anal open- 

 ing Discozerconidae 



2. Male genital opening at anterior margin of sternal plate; no dark 

 transverse bands on sternal plate of nymph 3 



Male genital opening in special presternal plate; sternal plate 

 usually with dark transverse band in nymph Poecilochiridae 



3. Females without jugular plates; copulatory suckers absent in male 4 



Females with jugular plates; copulatory suckers on raised cone of 

 ventroanal plate Aceosejidae 



4. Podosoma and opisthosoma insensibly fused; no constriction be- 

 tween the two regions 5 



Body elongated; opisthosoma separated from podosoma by deep 

 furrow Rhodacaridae 



5. Lateral, ventral, anterior projections of pedipalpal coxae not har- 

 poon-shaped; chelicerae chelate or stylettiform 6 



Females with lateral, ventral, anterior projections of pedipalpal 

 coxae harpoon-shaped; chelicerae without fixed digit; movable 

 digit with large, recurved teeth Ixodorhynchidae 



6. Base of gnathosoma forms narrow sheath for chelicerae 7 



Base of gnathosoma forms broad cavity or camerostome that 

 encloses chelicerae but not palps Spelaeorhynchidae 



7. Coxae movable 8 



u^ 



