Leptocera Olivier, 1813

Buck, Matthias & Marshall, Stephen A., 2009, Revision of New World Leptocera Olivier (Diptera, Sphaeroceridae), Zootaxa 2039 (1), pp. 1-139 : 16-20

Key to New World species of Leptocera Olivier

1 Most species micropterous ( Figs. 11–15; except L. duplicata ). Mid tibia with lowermost bristle of proximal posterodorsal series very long ( Fig. 17: l pd; longer than other bristles on mid tibia), more or less shifted distally (usually inserted at or below middle of tibia) ( Chile: Robinson Crusoe I.).................( L. cultellipennis subgroup) ... 2

- Macropterous. Mid tibia with lowermost bristle of proximal posterodorsal series shorter at least than distal dorsal bristle ( Fig. 16), not shifted distally (inserted at least slightly above middle of tibia) (widespread, absent from Robinson Crusoe I. except L. caenosa )......................................................................................................................... 5

2 Wings fully developed ................................................................................................................. L. duplicata Richards

- Micropterous ( Figs. 11–15)........................................................................................................................................... 3

3 Wing rudiment elongate with pointed apex ( Fig. 13); wing blade lacking veins beyond R 1 and behind costa. Scutum with four dorsocentral bristles (as in Fig. 109). Hind margin of male sternite 5 without enlarged scales ( Fig. 113). Fused female tergite 10 + cerci fairly well developed, ca. twice as wide as long ( Fig. 114) ......................................... ............................................................................................................................................ L. cultellipennis (Enderlein)

- Wing rudiment wedge-shaped with truncate apex; wing blade with several veins beyond R 1 and behind costa. Scutum with 5 or 4 dorsocentrals. Hind margin of male sternite 5 with or without enlarged scales. Fused female tergite 10 + cerci extremely reduced, over 5x as wide as long (e.g., Fig. 128) ............................................................ 4

4 Wing veins R 4+5 and M not fused or with point-like fusion at level of r-m ( Figs. 11, 12); last sector of R 4+5 thus arising far basad of level of apex of discal cell. Mid tibia with small dorsal and ventral posteroapical setae ( Fig. 19). Posterior margin of male sternite 5 with 3–5 conspicuously enlarged scales ( Fig. 127). Distal portion of spermathecae with bumpy surface ( Fig. 129) ......................................................................... L. ellipsipennis Richards

- Wing veins R 4+5 and M fused along apical portion of discal cell ( Figs. 14, 15); last sector of R 4+5 thus arising at or just basad of level of apex of discal cell. Mid tibia with small dorsal posteroapical seta ( Fig. 18, ventral posteroapical indistinguishable from surrounding setulae). Posterior margin of sternite 5 without enlarged scales ( Fig. 134). Distal portion of spermathecae with finely striate surface ( Fig. 136) ........................................ L. parallelipennis Buck sp.n.

5 Thorax bicoloured, brown with clearly delimited yellow stripes extending from postpronotal lobe to posterior corner of notopleuron ( Fig. 1). No hairs between paramedian rows of enlarged acrostichals. Setulae of costal sector 1 unusually short ............................................................................................................................. L. schlingeri Richards

- Thorax more or less unicolorous; coloration at most a little lighter along sutures; sometimes with distinct pruinose pattern. Scutum with 1–2 rows of hairs between rows of enlarged acrostichals, or acrostichals of uniform size. Setulae of costal sector 1 normal, long ( Fig. 10) .......................................................................................................... 6

6 Orbit with 1(–4) additional setulae between upper orbital and inner vertical bristles ( Fig. 2: ad s; sometimes absent on one side). Posteroapical bristles of mid tibia short (as in Figs. 19, 20; except L. sphaerotheca sp.n.). Male cerci desclerotized and small, pad-like (e.g., Figs. 38, 39). Female tergite 7 long, its medial length at least as great as length of fused tergite 10 + cerci (e.g., Figs. 42, 66) ...............................................................( L. caenosa group*) ... 7

- Orbit without additional setulae between upper orbital and inner vertical bristles. Posteroapical bristles of mid tibia frequently long ( Figs. 24–29). Male cerci usually well developed and sclerotized (except L. plax group), variously shaped. Female tergite 7 short, its medial length less than length of fused tergite 10 + cerci (e.g., Figs. 152, 236, 284; except L. insularum sp.n.)........................................................................................................................................... 17 * Excluding L. cultellipennis subgroup.

7 Palpus inflated, at most 3.5x as long as wide. Uppermost orbital setula inclinate (sometimes absent on one side). Arista long-pubescent ( Fig. 6). Scales at hind margin of male sternite 5 slender, with fine tips ( Figs. 49, 58) ........... 8

- Palpus slender, at least 4.5x as long as wide. Uppermost orbital setula usually exclinate (except in L. mendozana and exceptional specimens of L. gongylotheca sp.n. and L. argentinica sp.n.). Arista short- to long-pubescent ( Figs. 4–6). Scales at hind margin of male sternite 5 usually stout, with narrowly rounded tips (e.g., Figs. 65, 72; except L. aequilimbata : Fig. 41)................................................................................................................................................... 9

8 Male sternite 5 with desclerotized posteromedial area wide ( Fig. 49). Posterior section of surstylus slender, curved medially ( Fig. 48); anterior process of surstylus with apex conspicuously pointed ( Fig. 50). Female tergite 7 usually with narrow shining median stripe ( Fig. 52) (widespread).......................................................... L. caenosa (Rondani)

- Male sternite 5 with desclerotized posteromedial area small, triangular ( Fig. 58). Posterior section of surstylus stout and straight ( Fig. 56); apex of anterior process weakly pointed ( Fig. 55). Female tergite 7 pruinose throughout ( Fig. 59) (California, Argentina) ......................................................................................................... L. erratica Buck sp.n.

9 Mid tibia with bristle above distal dorsal short, at most as long as bristle above distal anterodorsal. Male sternite 5 with posteromedial emargination ( Fig. 65). Female tergite 7 pruinose throughout, paramedian pair of setae neither unusually enlarged nor cruciate ( Fig. 66). Female sternite 7 with simple hind margin (widespread)........................ 10

- Mid tibia with bristle above distal dorsal long, clearly longer than bristle above distal anterodorsal. Male sternite 5 with straight hind margin (e.g., Fig. 72; often appearing emarginate in undissected specimens through inward folding of posteromedial desclerotized area). Female tergite 7 usually with shining median stripe ( Fig. 73, except in L. aequilimbata and probably L. longilimbata sp.n.), paramedian pair of setae strongly developed and usually cruciate (non-cruciate in atypical specimens). Female sternite 7 with hind margin thickened and shining (Andean countries from Ecuador to Tierra del Fuego) .............................................................................................................. 11

10 Mid tibia with short posteroapical bristles ( Fig. 20). Female spermatheca elongate ( Fig. 67). Neotropical specimens usually with well developed yellow areas on lower frons, face, gena and legs. 0–1,800 m in Central America ( Canada to Argentina including Caribbean) ............................................................................. L. erythrocera (Becker)

- Mid tibia usually with long posteroapical bristles* ( Fig. 21). Female spermatheca spherical ( Fig. 107). Usually darker than Neotropical L. erythrocera . 700–2,950 m in Central America (southern TX, AZ to Panama) ................... ............................................................................................................................................. L. sphaerotheca Buck sp.n. *Note. This character shows geographic variation: towards the southern part of the range the bristles become shorter, and the character is thus not very reliable for separating specimens from Costa Rica and Panama. Males from these countries can sometimes not be identified with certainty.

11 Mesoscutum and scutellum with heavy greyish-brown pruinosity ( Fig. 2). Frons orange-brown between orbital plates and in front of ocellar triangle ( Fig. 2). Arista short- to medium-pubescent ( Figs. 4, 5) ( Argentina, Bolivia).... ..................................................................................................................................................................................... 12

- Mesoscutum and scutellum lightly pruinose, subshining (as in Fig. 37). Frons at most obscure reddish anteriorly (except in some L. mendozana , which has the arista long-pubescent as in Fig. 6)..................................................... 13

12 Spermatheca spherical ( Fig. 74) .......................................................................................... L. gongylotheca Buck sp.n.

- Spermatheca elongate ( Fig. 46) ............................................................................................. L. argentinica Buck sp.n. Note: Males of these two species cannot be distinguished morphologically.

13 Arista short-pubescent ( Fig. 4).................................................................................................................................... 14

- Arista medium- to long-pubescent ( Figs. 5, 6) ........................................................................................................... 15

14 Hind margin of male sternite 5 with shorter, apically tapered scales that become shorter laterally ( Fig. 41). Female terminalia as in Figs. 42–44 ( Peru to Argentina) ......................................................................... L. aequilimbata Duda

- Hind margin of male sternite 5 with long, blunt-tipped scales of subequal length ( Fig. 79). Female unknown ( Chile) .............................................................................................................................................. L. longilimbata Buck sp.n.

15 Mid tibia with bristle above distal dorsal bristle long, usually more than 0.75x (rarely only 0.6x) as long as distal anterodorsal. Male sternite 5 without pale desclerotized area in front of posteromedian field of dense microtrichia; hind margin with 4–6 long scales ( Fig. 98). Male cercus with small, finger-like medial process ( Fig. 95). Distal portion of female spermatheca with bumpy surface ( Fig. 100) ( Ecuador, Peru) .................... L. papallacta Buck sp.n.

- Mid tibia with bristle above distal dorsal bristle shorter, at most 0.6x as long as distal anterodorsal. Male sternite 5 with pale desclerotized area ( Fig. 83: da) in front of posteromedian field of dense microtrichia; hind margin with 6–14 smaller scales. Male cercus without finger-like process. Distal portion of female spermatheca with striate or bumpy surface ( Peru to Argentina, Chile) .................................................................................................................. 16

16 Male sternite 5 with pale medial desclerotized area bare, its hind margin with 11–14 long scales ( Fig. 83). Male cercus simple ( Fig. 81). Posterior section of surstylus with three spine-like apical bristles ( Fig. 81). Distal portion of female spermatheca with bumpy surface ( Fig. 85). Uppermost orbital setula inclinate (sometimes absent on one side). Arista long-pubescent (similar to Fig. 6) (south Peru to north Argentina) ..................... L. mendozana Richards

- Male sternite 5 with pale medial desclerotized area microtrichose, its hind margin with 6–10 long scales ( Fig. 90). Male cercus with transparent medial lamella ( Fig. 88: lp). Posterior section of surstylus with two spine-like apical bristles ( Fig. 88). Distal portion of female spermatheca with weakly striate surface ( Fig. 92). Uppermost orbital setula exclinate. Arista medium-pubescent ( Fig. 5) ( Chile, central and south Argentina) ............................................. .............................................................................................................................................. L. neocurvinervis Richards

17 Mid tibia with posteroapical bristles extremely unequal: ventral one greatly enlarged and dorsal one very short ( Fig. 29). Acrostichals uniform. Male sternite 5 with spinulose lobe on each side of deep posteromedial emargination ( Fig. 275) ( Venezuela) ............................................................................................................................ L. nigra Olivier

- Mid tibia with posteroapical bristles of similar length (or ventral one absent: L. plax sp.n.), short or long but always shorter than in L. nigra . Often with enlarged acrostichals near middle of scutum (except L. fulva group). Male sternite 5 without lobes and at most with shallow posteromedial emargination ........................................................ 18

18 Lower orbital bristle short, 0.5–0.6x as long as upper one ( Fig. 3). Acrostichals completely uniform, short and hairlike. Basal half of mid tibia with lowermost bristle of posterodorsal row short, 0.5–0.6x as long as lowermost bristle of anterodorsal row. Scutellum velvety, contrasting with subshining scutum ( Fig. 9) (Neotropical, south Florida) ..... ......................................................................................................................................................... ( L. fulva group)...19

- Lower orbital of normal size, only slightly shorter than upper one (at least 0.8x as long). At least some acrostichals of paramedian rows enlarged and/or mid tibia with lowermost bristle of proximal posterodorsal series long, subequal in length to lowermost bristle of anterodorsal row. Scutellum usually subshining, if velvety then scutum also in part velvety......................................................................................................................................................................... 23

19 Male cercus bifurcate. Posterior section of surstylus lacking series of short, stout, blunt-tipped bristles ( Figs. 233, 247). Female sternite 7 emarginate or slightly convex posteromedially ( Figs. 238, 252).......................................... 20

- Male cercus simple. Posterior section of surstylus frequently with three short, stout, blunt-tipped bristles near apex (e.g., Fig. 240). Posterior margin of female sternite 7 distinctly biemarginate (e.g., Fig. 266).................................. 21

20 Male sternite 5 with scales at posterior margin very numerous ( Fig. 235). Posterior section of surstylus with thick apical bristle relatively short and only slightly curved ( Fig. 233). Fused female tergite 10 + cerci with a very long and conspicuous pair of setae in basal half ( Fig. 236). Female sternite 7 emarginate posteromedially ( Fig. 238) ( Mexico to Peru, Brazil) ........................................................................................................... L. dicrofulva Buck sp.n .

- Male sternite 5 with scales at posterior margin less numerous ( Fig. 249). Posterior section of surstylus with thick apical medially directed bristle long and curved ventrally in a wide arc ( Fig. 247). Enlarged pair of setae of fused female tergite 10 + cerci much shorter and inserted in distal half ( Fig. 250). Female sternite 7 slightly convex posteromedially ( Fig. 252) ( Puerto Rico, Dominican Republic) ............................................. L. insularum Buck sp.n.

21 Posterior section of surstylus with three hair-like tapered bristles apically ( Fig. 261). Posteromedian projection of female sternite 7 broadly rounded ( Fig. 266) ( Venezuela to northern Argentina) ............... L. rhadinofulva Buck sp.n.

- Posterior section of surstylus with three stout blunt-tipped bristles apically (e.g., Fig. 240). Posteromedian projection of female sternite 7 more prominent and pointed, sometimes more or less arrow-shaped (e.g., Fig. 259) ................ 22

22 Posterior section of surstylus with strong, medially directed bristle inserted slightly above level of uppermost stout, blunt-tipped bristle of apical series ( Fig. 240) (south Florida, Caribbean, Mexico to Bolivia, Paraguay)..................... ............................................................................................................................................................ L. fulva (Malloch)

- Posterior section of surstylus with strong, medially directed bristle inserted well above apical series of stout bristles ( Fig. 254) ( Panama to Ecuador, Venezuela) .......................................................................... L. prolixofulva Buck sp.n. Note: Females of these two species cannot be reliably separated.

23 Arista long-pubescent (similar to Fig. 6). Neotropical species (southern Mexico to Ecuador).................................. 24

- Arista short-pubescent (similar to Fig. 4). Nearctic species ( Canada, U.S.A.)......................( L. fontinalis group*)...28 * Excluding L. cymatonota subgroup.

24 Mid tibia with bristle above distal dorsal long: distinctly longer than bristle above distal anterodorsal, and about half as long as distal anterodorsal. Male sternite 5 without enlarged scales at posterior margin ( Fig. 214). Female sternite 7 with densely microtrichose posteromedial tab ( Fig. 217)............................................( L. cymatonota subgroup)...25

- Mid tibia with bristle above distal dorsal short: at most as long as bristle above distal anterodorsal, and at most 1/3 length of distal anterodorsal. Male sternite 5 with heavily sclerotized enlarged scales at posterior margin ( Fig. 283, 293). Female sternite 7 with straight hind margin or with shining, bare posteromedial projection ............................... ........................................................................................................................................................ ( L. plax group) ... 26

25 Scutellum with six pairs of bristles, three of which are small and hair-like. Thoracic scutum with weak pruinose pattern as in Fig. 8 ( Costa Rica, Panama). ................................................................................. L. hexadike Buck sp.n.

- Scutellum with the usual four pairs of bristles. Thoracic scutum with conspicuous, irregular, pruinose pattern as in Fig. 7 ( Mexico, Guatemala) ................................................................................................... L. cymatonota Buck sp.n.

26 Mid tibia with one posteroapical bristle only ( Fig. 22). Male sternite 5 with ca. 8 enlarged scales at posterior margin ( Fig. 283). Fused female tergite 10 + cerci with more or less parallel lateral margins ( Fig. 284) ( Ecuador)................. ........................................................................................................................................................... L. plax Buck sp.n.

- Mid tibia with two posteroapical bristles ( Fig. 23). Male sternite 5 only with a pair of enlarged scales at posterior margin ( Fig. 293; male of L. posteronitens sp.n. unknown). Fused female tergite 10 + cerci with lateral margins converging towards apex from almost near base ( Figs. 287, 294) (C. America) ....................................................... 27

27 Female sternite 7 only slightly convex posteriorly, uniformly dull grey ( Fig. 296). Male terminalia as in Figs. 290–293 ( Costa Rica, Panama) ..................................................................................................... L. tapanti Buck sp.n .

- Female sternite 7 strongly protruding posteromedially, medial lobe shining black ( Fig. 289). Male unknown ( Mexico, Guatemala) .......................................................................................................... L. posteronitens Buck sp.n.

28 Mid tibia with bristle above distal dorsal bristle long, distinctly longer than anteroapical bristles............................ 29

- Mid tibia with bristle above distal dorsal short, at most as long as anteroapical bristles ........................................... 36 Note: the variable L. kanata sp.n. keys both ways.

29 Males ........................................................................................................................................................................... 30

- Females ....................................................................................................................................................................... 33

30 Ventral lobe of surstylus somewhat angulate and with scattered short bristles, posterior section of surstylus with few bristles (at most four) on dorsal (posterior) surface ( Fig. 185) (NU to AK, in Rocky Mts. south to CO) ..................... .......................................................................................................................................................... L. parafinalis Papp

- Ventral lobe of surstylus either evenly rounded ( Figs. 158, 163) or distinctly notched (Fig. 177); posterior section of surstylus with numerous bristles (more than four) on dorsal (posterior) surface, usually restricted to basal half ( Figs. 159, 164, 178) ............................................................................................................................................................. 31

31 Ventral lobe of surstylus with distinct notch in front of large, posterior bristle (Fig. 177). Enlarged acrostichals normal, longest one at most 0.75x as long as lower orbital bristle (YT, AK, in Rocky Mts. south to NM) .................. ............................................................................................................................................. L. neovomerata Buck sp.n.

- Ventral lobe of surstylus evenly rounded in front of large, posterior bristle ( Figs. 158, 163). Enlarged acrostichals long, longest one usually>0.75x as long (up to same length) as lower orbital bristle ............................................... 32

32 Sternite 5 with numerous long soft pale hairs in desclerotized posteromedial area. Anterior section of surstylus with anterior process stouter; ventral lobe with bristles more slender, and enlarged posterior bristle inserted more dorsally (posteriorly) ( Fig. 158) (Atlantic Coast from NF to NH) .............................................................. L. fontinalis (Fallén)

- Sternite 5 with fewer shorter straight hairs in desclerotized posteromedial area ( Fig. 166). Anterior section of surstylus with anterior process more slender; ventral lobe with bristles stouter (less so in western specimens), and enlarged posterior bristle inserted more ventrally (anteriorly) ( Fig. 163) (QC and MA to AK;?Rocky Mtn. states) ... ......................................................................................................................................... L. kanata Buck sp.n. (in part) Note: most specimens of L. kanata sp.n. key to couplet 39 below.

33 Hind margin of sternite 7 straight, with sharply defined, slightly darkened and shining edge (i.e., devoid of microtrichia) ( Fig. 162)............................................................................................................................................... 34

- Hind margin of sternite 7 sometimes produced medially ( Fig. 169), with poorly defined, dull, microtrichose edge (i.e., sternite gradually becoming paler and more membranous posteriorly) ............................................................. 35

34 Enlarged acrostichals very long, longest one at least 0.8x (usually as long) as lower orbital bristle (Atlantic Coast from NF to NH) ............................................................................................................................. L. fontinalis (Fallén)

- Enlarged acrostichals normal, longest one at most 0.65x as long as lower orbital bristle (YT, AK, in Rocky Mts. south to NM) ....................................................................................................................... L. neovomerata Buck sp.n.

35 Hind margin of sternite 7 straight; sternite 8 with lateral margins slightly convex near middle, hind margin with narrow, shallow notch between posteromedial and posterolateral lobes ( Fig. 191) (NU to AK, in Rocky Mts. south to CO) ................................................................................................................................................... L. parafinalis Papp

- Hind margin of sternite 7 produced medially; sternite 8 with lateral margins distinctly angulate near middle, hind margin with wide, deep notch between posteromedial and posterolateral lobes ( Fig. 169) (QC and MA to AK;?Rocky Mtn. states) ........................................................................................................ L. kanata Buck sp.n. (in part) Note: most specimens of L. kanata sp.n. key to couplet 39 below.

36 Posteroapical bristles of mid tibia unequal (with dorsal one clearly shorter than ventral one) and usually longer, ventral bristle often clearly extending beyond level of insertion of ventrobasal metatarsal bristle ( Fig. 26). Hind margin of female sternite 7 straight ( Fig. 176). Spermathecae without or with small and very shallow apical invagination, surface spiculate mainly near base ( Fig. 175)....................................................................................... 37

- Posteroapical bristles of mid tibia of same length and usually shorter, ventral one not clearly extending beyond level of insertion of ventrobasal metatarsal bristle ( Fig. 28). Hind margin of female sternite 7 with more or less developed medial projection ( Figs. 154, 169). Spermathecae with narrow but deep apical invagination, surface fairly evenly spiculate ( Fig. 197) ..................................................................................................................................................... 38

37 Anterior section of surstylus with anterolateral corner angulate and darker than surrounding area ( Figs. 170, 172: as). Relatively common ( Canada and northern U.S., in mountains south to WY, northern CA) .... L. neofinalis Buck sp.n.

- Anterior section of surstylus with anterolateral corner rounded and concolorous with surrounding area ( Figs. 155, 156). Rare (LB, NS to AK) ................................................................................................................. L. finalis (Collin) Note: we were unable to separate females of these two species.

38 Anterior process of surstylus angulate and stout ( Fig. 148). Female sternite 8 with lateral margins slightly sinuate ( Fig. 154) (YT, AK) .............................................................................................................. L. angulispina Buck sp.n.

- Anterior process of surstylus rounded and more slender ( Figs. 163, 192). Female sternite 8 with lateral margins angulate ( Figs. 169, 198) ............................................................................................................................................ 39

39 Anterior section of surstylus with at least one long bristle that is more than half as long as the large posterior bristle; anterior process moderately slender ( Fig. 163) (QC and MA to AK;?Rocky Mtn. states) ........................................... ......................................................................................................................................... L. kanata Buck sp.n. (in part)

- Anterior section of surstylus with short bristles only, all of which are less than half as long as the large posterior bristle; anterior process very slender ( Fig. 192) (BC,?Rocky Mtn. states) ............................. L. tenuispina Buck sp.n. Note. We were unable to separate females of these two species. The identity of females from Rocky Mountain states remains uncertain.