| 1 |
Body vermiform (worm-like) |
Demodex |
| Body not vermiform |
2 |
| 2 |
Body elongated; often appears laterally flattened |
Fur mite 3 |
| Body dorsoventrally flattened |
4 |
| 3 |
On cats; flap-like chitinous sternal extensions |
Lynxacarus |
| On guinea pigs |
Chirodiscoides |
4
|
With feather-like setae on dorsal surface |
5 |
| Setae on dorsal surface not feather-like |
6 |
5
|
Larvae only are parasitic |
Trombiculidae |
| Adults parasitic; palpi with claws; legs 3 & 4 separated from legs 1 & 2 |
Cheyletiella |
6
|
Coxae close together on anterior part of body; spiracles in middle of body lateral to coxae |
[Mesostigmata] 7 |
| Coxae spread around body |
10 |
| 7 |
Genital plate absent; from nasal passage or airway |
11 |
| Genital plate well-defined (can be difficult to see); external parasites |
8 |
| 8 |
Anal plate oval |
Ornithonyssus |
| Anal plate a rounded triangle |
9 |
| 9 |
Chelicerae with a single stylet, usually on poultry |
Dermayssus |
| Chelicerae large, with celae (long, scissor-like structures on the end of the chelicerae) |
Railletia |
10
|
Coxae evenly spread around body; all legs short; body disc-like |
Psorergates |
| Coxae 1 & 2 widely separated from coxae 3 & 4 |
12 |
| 11 |
From nasal cavity of dogs; peritreme short finishing between coxae 3 & 4 |
Peumonyssoides |
| In lungs of finches, canaries and other cage birds, no peritreme |
Sternostoma |
12
|
Posterior pairs of legs almost or completely concealed under abdomen |
[Sarcoptidae] 13 |
| At least 3 pairs of legs projecting beyond abdomen |
[Psoroptidae] 15 |
13
|
Dorsum with stout spines and pointed triangular scales; anus terminal |
Sarcoptes |
| Dorsum with pointed triangular scales but no stout spines; anus dorsal; on rodents (especially guinea pigs) |
Trixacarus |
| Dorsum with neither stout spines nor pointed triangular scales |
14 |
| 14 |
Very long seta on leg 3 (male) or legs 3 & 4 (female); anus dorsal; on mammals (especially cats or rodents) |
Notoedres |
| No long setae either on legs 3 or 4; parasitic on birds |
Cnemidocoptes |
15
|
Pedicels of tarsal suckers long and segmented |
Psoroptes |
| Pedicels of tarsal suckers short and non-segmented |
16 |
| 16 |
Male - prominent posterior lobes on tip of abdomen; tarsal suckers on all legs; Leg 3 with 1 long setae; Female - tarsal suckers on legs 1, 2 & 4;leg 3 with 2 long setae; Parasite of ungulates |
Chorioptes |
| Male - no posterior lobes; tarsal suckers on all legs; 2 long setae on legs 3 & 4; Female - tarsal suckers on legs 1 & 2; leg 4 vestigial; Parasite of small animals |
Otodectes |
