Scatopsidae

Amorim, Dalton de Souza & Brown, Brian V., 2020, Urban Scatopsidae (Diptera) of Los Angeles, California, United States, Insect Systematics and Diversity 4 (1), No. 1, pp. 1-41 : 38-39

Key to the genera and species of Scatopsidae of California (asterisk indicates genus or species collected in the BioSCAN project)

1. Area of frons between antennae and eye-bridge only with microtrichia; epimeron I undivided; wing membrane with no macrotrichia; base of M 1 + 2 with long fusion to R 5; apex of hind tibia slightly swollen and flattened ( Figs. 1 , 15 , and 28–32) ....... Ectaetiinae ... Ectaetia Enderlein ... Ectaetia betzi sp.nov. *

– Area of frons between antennae and eye-bridge with setae; epimeron I partially or entirely divided into a dorsal and a ventral sclerite connected anteriorly; wing membrane either with macrotrichia or bare; base of M 1 + 2 either not fused to R 5 or with a very incipient fusion; apex of hind tibia not swollen or flattened ................................................................................ 2

2. R 5 gradually approaching C; epimeron I partially divided, dorsal sclerite with anterior spiracle; scutellum only with fine setae; sperm pump attached to the terminalia ( Figs. 2 , 16 , and 33–41) ................... .................................................................. .... Psectrosciarinae ... Psectrosciara Enderlein * ...................... 3

– R 5 abruptly approaching C close to apex; epimeron I entirely divided into a dorsal sclerite with the spiracle completely separated from a ventral sclerite; scutellum with some longer setae besides shorter setae; sperm pump free in the abdomen ............ ........................................... Scatopsinae ................................ 6

3. Apex of tibiae and tarsal segments with stout setae..................4

– Apex of tibiae and tarsal segments without stout setae............ 5

4. Wings short, not projected beyond apex of abdomen, male gonocoxites very short .................... ............................................ ....................................................................... P. brevipennis Cook

– Wings extending beyond tip of abdomen, male gonocoxites apically extended ................................. ....................................... ............................................................................ P. californica (Cole)

5. Male tergite 10 slightly expanded apically ................................ ................................. P. bakeri Cook

– Male tergite 10 slightly slender, not expanded apically ............. .................... P. gonzalezae sp.nov. *

6. CuA sigmoid; setae present at least on CuA; stem of halter without setae .............................. ........................................... .......................................................... Rhegmoclematini ........ 7

– CuA with a single fold toward posterior margin; posterior wing veins and wing membrane without setae; stem of halter with setae or bare .......................................................................... 9

7. Male sternite 7 rectangular, not shield-shaped; without a regular row of supra-alar setae ..................... .................................. ...................................... Parascatopse Cook ... Parascatopse sonorensis Cook

– Male sternite 7 shield-shaped; regular row of supra-alar setae present .................................................. ................... .......................................................................................... Rhegmoclemina Enderlein ..................................................... 8

8. Male terminalia with a pair of digitiform distal extensions laterally on T9 ................................. ................................... ................................................. Rhegmoclemina bimaculata (Melander)

– Male terminalia with no digitiform distal extensions laterally on T9 ......................................... .................................................. .................................. Rhegmoclemina scrobicollis (Melander)

9. Palpus usually small, ovoid or obovate, never apically acute; R 5 extending well beyond mid of wing ........................................... ............................................................................................ 10

– Palpus well developed, reniform, sometimes acute apically; R 5 extending at most slightly beyond middle of wing, most reaching C often before middle of wing .............. Swammerdamellini ........ 13

10. Body shining; wing membrane shining, microtrichia short; CuA gently curved toward margin on basal third; sternite 1 produced laterally ...................................... Scatopsini .............. 11

– Body dull; wing membrane not shining, microtrichia long; CuA strongly curved toward margin on basal third; sternite 1 not produced laterally; dorsal arms of sternite 9 not elongate ......... ............................................... Colobostematini .................. 12

11. Supranumerary cross-vein arising from M 1; male hind leg tarsomere 1 at most as long as tarsomere 2, with some stouter setae ( Figs. 3 , 17 , and 42–46) .......... Scatopse Geoffroy ... Scatopse notata Linnaeus *

– Without supranumerary cross-vein on M1; male hind leg tarsomere 1 at least slightly longer than tarsomere 2, with no distinctive setae ..................................................................... ............................................................................................... Apiloscatopse Cook ... Apiloscatopse collaris (Melander)

12. Flagellomeres with regular crown of setulae; supranumerary vein R 5 -M 1 complete; CuA strongly curved towards posterior margin, no second fold towards distal margin on distal half of CuA; eyes holoptic in both sexes ( Figs. 47–51 ) ..... Holoplagia Enderlein ... Holoplagia guamensis (Johannsen) *

– Flagellomeres with irregularly distributed setulae; eyes incompletely holoptic, especially so in females; supranumerary R 5 -M 1 incomplete or absent; CuA not strongly curved towards posterior margin, a second fold toward distal margin present on distal half of CuA ................................... .................................. ............................................................................ Colobostema Enderlein

13. Medial fork restricted to distal end of wing, much shorter than stem; R 5 very short, reaching C close to R 1 ( Figs. 5, 6 , 21, 22 , and 57–61) ... Swammerdamella Enderlein ... Swammerdamella marginata Cook *

– Medial fork much longer than stem; R 5 reaching C not close to R 1 ........................................................................................ 14

14. Abdominal sternite 2 and 3 sclerotized ................................. 15

Abdominal sternites 2 and 3 unsclerotized, typical abdominal pleura covering ventral side of abdomen in these segments ... 16

15. Spiracular sclerite elongated; male tergite 7 with conspicuous asymmetrical medial distal process; aedeagus long, coiled; female sternite 7 with lunular medial posterior incision ( Figs. 7, 8 , 19, 20 , and 62–65) .......................................................... Coboldia Melander ... Coboldia fuscipes (Meigen) *

– Spiracular sclerite about as high as long, with acute anterodorsal process; male tergite 7 with no asymetrical medial process, aedeagus not coiled; female sternite 7 without lunular medial posterior incision ( Figs. 4 , 18 , and 52–56) ................ Aztecatopse Haenni and Huerta ... Aztecatopse huertai , sp.nov. *

16. Scutum and abdomen shining; tergite 9 projected posteriorly ....................... Akorhexoza Cook

– Scutum and abdomen mostly dull; tergite 9 not projected posteriorly ................................................................................ 17

17. Sternite 4 produced. Tergite 9 produced ventrally as a beak-like process ( Figs. 9, 10 , 23 , 24, and 67–74) ............................... ................................................ Quateiella Cook ... Quateiella quatei (Cook) *

– Sternite 4 not produced. Tergite 9 without beak-like ventral extension ................................................................................ 18

18. Aedeagal plate absent; base of parameres not displaced distally .... Abrhexosa Freeman * ..................................................... 19

Aedeagal plate present; base of parameres displaced distally ( Figs. 14 and 27 ) ....................................... ........................... ..................................................... Cooka Amorim ... Cooka melanderi Cook *

19. Meral setae on thorax pleura present, male tergite 7 with median notch on posterior margin; female tergite 8 with a pair of lateral projections wide distally inclined towards mid of terminalia ( Figs. 11, 12 , 25, 26 , and 75–81) .............................. ....................................................... Abrhexosa grossa (Cook) *

– Meral setae on thorax pleura absent, male tergite 7 entire; female tergite 8 with a pair of digitiform projections medially ( Figs. 13 and 82–86 ) .................................. Abrhexosa ryckmanni (Cook) *

Figures

Figs. 1–6. Habitus. 1. Ectaetia betzi sp.nov., male holotype. 2. Psectrosciara gonzalezae sp.nov., female paratype. 3. Scatopse notata (Linnaeus), female. 4. Aztecatopse huertai sp.nov., female paratype. 5. Swammerdamella marginata Cook, male. 6. Swammerdamella marginata Cook, female.

Figs. 15–20. Abdomen. 15. Ectaetia betzi sp.nov, male holotype. 16. Psectrosciara gonzalezae sp.nov., female paratype. 17. Scatopse notata (Linnaeus), female. 18. Aztecatopse huertai sp.nov., female paratype. 19. Coboldia fuscipes (Meigen), male. 20. Coboldia fuscipes (Meigen), female (white arrow indicates the diagnostic lunulate sternite 7 posterior incision).

Figs. 47–51. Holoplagia guamensis (Johannsen), male. 47. Head, lateral view. 48.Thorax, lateral view. 49.Wing. 50. Segment 8 and terminalia, ventral view. 51. Segment 8 and terminalia, dorsal view.

Figs. 21–23. Abdomen. 21. Swammerdamella marginata Cook, male. 22. Swammerdamella marginata Cook, female. 23. Quateiella quatei (Cook), male. 24. Quateiella quatei (Cook), female.

Figs. 7–10. Habitus. 7. Coboldia fuscipes (Meigen), male (black arrow indicates the diagnostic tergite 8 spatulate projection). 8. Coboldia fuscipes (Meigen), female. 9. Quateiella quatei (Cook), male. 10. Quateiella quatei (Cook), female.

Figs. 11–14. Habitus. 11. Abrhexosa grossa (Cook), male. 12. Akorhexosa grossa (Cook), female. 13. 10. Abrhexosa ryckmani (Cook), male. 14. Cooka melanderi (Cook), male.

Figs. 25–27. Abdomen.25. Akorhexosa grossa (Cook), male. 26. Akorhexosa grossa (Cook), female. 27. Cooka melanderi (Cook), male.

Figs. 82–84. Abrhexosa ryckmani (Cook), male. 82. Head, lateral view. 83.Thorax, lateral view. 84.Wing.

Figs. 85–86. Abrhexosa ryckmani (Cook), male. 85. Segment 8 and terminalia, ventral view. 86.Terminalia,ventral view.