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) *