Megaselia

Disney, R. Henry L., 2012, Scuttle flies (Diptera: Phoridae) caught at dead mice in S. W. Finland, Zootaxa 3298 (1), pp. 30-42 : 36-37

Key to Megaselia females caught at dead mice

Note: Variable species are keyed both ways at several couplets

1 Mesopleuron with hairs and sometimes bristles at hind margin.................................................. 2

- Mesopleuron bare.................................................................................... 13

2 Vein Sc does not reach vein 1 (R1)........................................................................ 3

- Vein Sc runs to and fuses with vein 1. (Labella with numerous small spinules below. Typically with at least one bifid spinule in the apical comb of the hind tibia. Abdominal tergite 4 to tip of abdomen as Fig. 1 . Lobes at rear of abdominal sternum 8 as Fig. 2 . DCM as Figs 3 and 4 ).................................................................... altifrons (Wood)

3 Scutellum with two pairs of robust bristles, even though the anterior pair may be a little shorter than those behind......... 4

- Scutellum with an anterior pair of small hairs and a posterior pair of bristles....................................... 6

4 With three robust bristles on the notopleuron................................................................ 5

- With only two robust bristles on the notopleuron............................................................ 13

5 Costal cilia of section 3 shorter than outermost axillary bristle. Hind femora entirely yellow.................. Species F5

- Costal cilia longer than outermost axillary bristle. Hind femora yellow with brown tips..................... Species F13

6 Hind femora brown....................................................................................7

- Hind femora yellow with brown tips............................................................... Species F2

7 With three robust bristles on the notopleuron................................................................ 8

- With only two robust bristles on the notopleuron. (More than 30 small spinules on each labellum below and apicolaterally)................................................................................................ Species 9

8 Haltere knob brown. Mesopleuron, in addition to the hairs, with a long bristle at rear margin. Posterodorsal on hind tibia robust. The lobes at rear of abdominal sternum 8 are extensions of a sternite 8 ( Fig. 19)................... major (Wood)

- Without this combination............................................................................... 9

9 Mesopleuron, in addition to the hairs, with a bristle at rear margin.............................................. 10

- Mesopleuron with hairs only............................................................................ 11

10 Costal cilia of section 3 subequal to or a little shorter than outermost axillary bristle. Abdominal tergite 6 with hind margin only about half as wide as maximum breadth....................................................... Species F10

- Costal cilia clearly longer than outermost axillary bristle. Breadth of hind margin of T6 only a little less than maximum breadth........................................................................................... Species F14

11 Fewer than 20 spinules on each labellum below and apicolaterally. Palps yellow................................... 12

- More than 30 small spinules on each labellum below and apicolaterally. Palps yellowish brown................ Species F7

12 Abdominal tergite 7 broader than long and not narrowing towards hind margin. Hind femora yellowish brown... Species F16

- T7 longer than broad and hind margin clearly less than width of front margin. Hind femora greyish brown...... Species F15

13 Scutellum with an anterior pair of short fine hairs and a posterior pair of robust bristles............................. 14

- Scutellum with two pairs of robust bristles, even though the anterior pair may be a little shorter than those behind........ 17

14 Vein Sc runs to and fuses with vein 1 (R1)................................................................. 15

- Vein Sc does not reach vein 1........................................................................... 16

15 Haltere knob yellow. Abdominal tergite 3 shorter than T4 and with a concave hind margin ( Fig. 12). (T5 and T6 as Fig. 11, Dufor’s crop mechanism variable – Figs 14–15 )............................................ breviterga (Lundbeck)

- Haltere knob brown. T3 as long as T4 and with a straight hind margin....................................Species F8

16 Hind femora yellow with brown tips. Only two bristles on notopleuron. With a single lobe with six long hairs at rear of abdominal sternum 8............................................................................... Species F11

- Hind femora brown. With three bristles on notopleuron. With a pair of lobes, each with three hairs, at rear of S8....................................................................................................... Species F6

17 Front margin of abdominal tergite 4 at most as wide as hind margin of T3 ( Fig. 23 and T 5 and T6 as Fig. 22 . Lobes at rear of abdominal sternum 8 as Fig. 24 and furca as Fig. 25 . Cerci less than twice as long as broad. Front margin of T7 almost as wide as hind margin of T6. Costa at least half length of wing......................................... ruficornis (Meigen)

- Without this combination.............................................................................. 18

18 Haltere knob yellow.................................................................................. 19

- Haltere knob brown. (Palps and all femora brown. Lobes at rear of abdominal sternum 8 whose microtrichia overreach their broadly convex tips)............................................................................ Species F4

19 With only 2 or 3 axillary bristles, which are all a little shorter than costal cilia of section 3. Hind femora yellowish brown. With sclerotised furca...............................................................................Species F1

- With at least 4 Ax bristles and without the other features in combination with this..................................20

20 Tips of lobes abdominal sternum 8 convex and devoid of microtrichia and lacking a sclerotised furca.................. 21

- Tips of lobes of S8 not so ( Fig. 9 ) and a sclerotised furca present ( Fig. 7 )............................. breviseta (Wood)

21 S8 lobes larger, tinged brown at rear and as Fig. 21. Abdominal tergites 4 to 6 as Fig. 20................ parnassia Disney

- S8 lobes smaller, with pale tips and as Fig. 16 . Abdominal tergites 4 to 6 as Fig. 18. (Dufour’s crop mechanism as Fig,17)........................................................................................... giraudii (Egger)

Figures

FIGURE 1. Megaselia altifrons female, dorsal face of abdomen from rear of tergite 3 onwards.

FIGURE 2. Megaselia altifrons female, left lobe at rear of ventral face of abdominal segment 8.

FIGURES 3–4. Megaselia altifrons female, Dufour’s mechanism from two different specimens.

FIGURES 14–15. Megaselia breviterga female, Dufour’s crop mechanism from two different specimens

FIGURES 22–23. Megaselia ruficornis female abdominal tergites. 22, T5 and T6; 23, T2 to T4. (Scale bar = 0.1mm).

FIGURES 5–10. Megaselia breviseta female, details of abdomen. 5, tergite 7; 6, sternite 7; 7, furca; 8, tubular organ; 9, right lobe at rear of sternum 8; 10, hypoproct. (Scale bars = 0.1mm).

FIGURES 24–25. Megaselia ruficornis female, details of abdomen. 24, lobes at rear of sternum 8; 25, furca. (Scale bar = 0.1mm).

FIGURES 16–17. Megaselia giraudii female, details of abdomen. 16, lobes at rear of sternum 8; 17, Dufour’s crop mechanism. (Scale bar = 0.1mm).