Key to species of Mesoplophora

1 Two pairs of anal setae present..................................................... subgenus Mesoplophora ....2

- Three to four pairs of anal setae present...............................................subgenus Parplophora ....23

2 Lamellar setae situated closer to rostral setae than to interlamellar setae............................. M. (M.) permodica

- Lamellar setae situated closer to interlamellar setae than to rostral setae........................................... 3

3 Sensilli with slightly fusiform head....................................................................... 4

- Sensilli without head................................................................................... 6

4 Sensilli smooth; lateral carinae of prodorsum absent.......................................... M. (M.) parapulchra

- Sensilli covered with spines; lateral carinae of prodorsum present............................................... 5

5 “Notogastral” setae long, setae c 3 longer than half of distance between setae c 3 and c p; nine pairs of rough ventral setae present........................................................................................ M. (M.) hauseri

- “Notogastral” setae short, setae c 3 shorter than half of distance between setae c 3 and c p; eight pairs of smooth ventral setae present......................................................................................... M. (M.) ignota

6 Prodorsal and most “notogastral” setae very short and fine..................................... M. (M.) brachysetosa

- Nearly all prodorsal and “notogastral” setae much longer and thicker than their alveoli............................... 7

7 Sensilli smooth....................................................................................... 8

- Sensilli covered with spines............................................................................ 13

8 Distance between rostral setae considerably longer than distance between interlamellar setae.............. M. (M.) bolivari

- Distance between rostral setae shorter than distance between interlamellar setae.....................................9

9 Exobothridial setae longer than diameter of bothridia; “notogastral” setae very long, setae c 3 longer than distance between setae c 3 and c p.......................................................................... M. (M.) longisetosa

- Exobothridial setae shorter than diameter of bothridia; “notogastral” setae in normal length, setae c 3 shorter than distance between setae c 3 and c p................................................................................10

10 Ten pairs of ventral setae present; formula of genital setae 5:2........................................ M. (M.) bacilla

- Eight or nine pairs of ventral setae present; formula of genital setae 6:1.......................................... 11

11 Nine pairs of ventral setae present; aggenital position with one pair of setae........................ M. (M.) parabacilla

- Eight pairs of ventral setae present; aggenital position without setae............................................. 12

12 Lateral carinae of prodorsum present; all “notogastral “setae similar in shape.......................... M. (M.) frogneri

- Lateral carinae of prodorsum absent; setae c 3 much thinner than other “notogastral” setae...... M. (M.) heterotricha sp. nov.

13 Formula of genital setae 5:2............................................................................ 14

- Formula of genital setae 6:1............................................................................ 16

14 Prodorsum with lateral carinae; setae e 1 and e 2 thicker than other “notogastral” setae.................... M. (M.) invisitata

- Prodorsum without lateral carinae; all “notogastral” setae similar in shape........................................15