Mesoconius Enderlein, 1922

Marshall, Stephen A., 2019, A revision of the genus Mesoconius Enderlein (Diptera, Micropezidae, Taeniapterinae), European Journal of Taxonomy 548, pp. 1-126 : 4-12

publication ID

https://doi.org/ 10.5852/ejt.2019.548

publication LSID

lsid:zoobank.org:pub:7BA0D937-437E-4252-8EF4-4F35E6B59445

persistent identifier

https://treatment.plazi.org/id/03DB2535-6F7D-FF98-0931-F84BFB48FCB7

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Plazi

scientific name

Mesoconius Enderlein, 1922
status

 

Mesoconius Enderlein, 1922 View in CoL

Mesoconius Enderlein, 1922: 176 View in CoL (type species: Mesoconius infestus Enderlein, 1922 View in CoL ).

Zelatractodes Enderlein, 1922: 169 (type species: Zelatractodes filipes Enderlein, 1922 View in CoL ) (synonymized in Marshall 2015).

Aristobata Frey, 1927: 69 (type species: Aristobata melini Frey, 1927 View in CoL = Zelatractodes filipes Enderlein, 1922 View in CoL ) (synonymized in Steyskal 1968).

Description

Length 11–21 mm. Colour variable between, and often within, species.

HEAD. Arista bare. Fronto-orbital bristles weak to strong, in one–two pairs with upper pair (if present) at or above level of upper ocelli, lower pair below level of lower ocellus near overlap between epicephalon and orbital plate. Postocellar and outer vertical bristles present or absent, inner vertical bristles always present, although sometimes very small. Lower frons usually elevated, forming a transverse, slightly scooped band in front of frontal vitta; frontal vitta usually broad and diamond- or teardrop-shaped and slightly elevated in front of ocelli but shape, elevation and extent variable. Face pale and weakly sclerotized on ventral third to half, broadly elevated to narrowly carinate dorsally; frons usually separated from antennal socket, exposing a suprantennal shelf or antennal base between antenna and lower margin of frontal plate. Clypeus shiny medially, microtrichose laterally or posterolaterally, normally slightly angled forward on pinned specimens. Palpus parallel-sided or nearly so, usually broad.

THORAX. Cervical sclerite usually with a swollen microtrichose posterior section sometimes (females only) with a whitish or dull posterior patch of sensillae; anterior section depressed, flat, bare and sometimes divided by a carina. Prosternum on two planes, anterior part depressed and narrow, posterior (main) part usually broad (narrow in M. bipleuron sp. nov.), usually microtrichose, often setose, rarely bare. Pronotum microtrichose, except for narrow anterolateral lobe. Scutum with two notopleural bristles and one posterior (prescutellar) dorsocentral bristle (rarely absent); scutellum usually with a few discal setulae and a single pair of long apical bristles (absent in M. garyi sp. nov. only). One or more fore tarsomeres of one or both sexes sometimes enlarged and flattened. Fore tibia longitudinally grooved, often inconspicuously so but sometimes strongly flattened and conspicuously sulcate on posterior face. Mid and hind femora densely microtrichose distally, bare or almost bare and shiny basally; hind femur usually at least slightly swollen distally. Katatergite usually at least slightly swollen, often very prominent with a nipple-like central process. Dorsocentral bristles in a single posterior pair, often reduced, rarely absent. Wing variable in colour, but usually darkened at least in distal half and often with an indistinct preapical clear area that is partially or completely divided into patches; some species with clear, uniformly pigmented or distinctly banded wing. Third costal sector (between R 2+3 and R 4+5) short, much less than half as long as second costal sector. Anal cell short, with a strong longitudinal crease or false vein in basal third. Costagial bristle relatively short, extending approximately to humeral crossvein.

ABDOMEN. Usually distinctly petiolate, with syntergite 1+2 elongate and pleuron of at least segment one reduced, rendering the base of the abdomen conspicuously slender (the closely related M. nigra sp. nov., M. quadritheca sp. nov. and M. ruficrus sp. nov. are exceptions, with only the basal portion of segment 1 constricted).

FEMALE ABDOMEN. Oviscape short and stout, with upper and lower surfaces fused to form a cylinder, usually directed posteriorly or ventrally, rather than strongly deflexed anteriorly as in many Taeniapterinae . Spermathecae (1+2, rarely 2+2) and associated ducts typically complex and often species-specific, usually with a distinct ventral receptacle on a broad bursa. In most species a relatively thick duct (paired spermathecal duct) leads to paired spermathecae, each of which is on a frequently elaborately sculptured or swollen stem; a smaller duct (single spermathecal duct) leads to a single (or rarely a pair of) small spermatheca(e). Spermathecal ducts either arise independently from apex of bursa or from a short or long common duct before splitting into paired and single ducts.

MALE ABDOMEN. Male S5 small to entirely reduced, S6 elongate to greatly reduced, often expanded posteriorly; S8 usually large and often different in colour and texture from preceding tergites and from epandrium; epandrium small to very small; ejaculatory apodeme variable in size. Hypandrium forming a short to long loop anteriorly (anterior margin either belt-like, scoop-like, or broad and twisted), posteriorly articulating with long anteroventral epandrial extensions and extending medially into a robust and microtrichose phallic plate. Postgonite small and inconspicuous, but apically broad, with small apical or preapical setae, basiphallus usually small and frame-like, but sometimes extended well beyond base of distiphallus; distiphallus divided into a broad basal part, a prominent phallic bulb, and (usually) a variously developed distal part.

Keys to the South American species of Mesoconius Enderlein, 1922 View in CoL

Some species of Mesoconius are sexually dimorphic for colour, and most show intraspecific variation in the conspicuous colour characters traditionally used to distinguish species. This infraspecific colour variation, combined with a very high level of local endemism, often made it difficult to match the limited fresh material to older names. Many species remain known only from single specimens taken at type localities that have not been practical to re-sample, such as Thiele’s collection localities in the Colombian Andes and the infamous late 19 th century Peruvian collection locality of “Callanga” ( Woytkowski 1974). For several of the species known only from older type specimens, genitalic characters are unavailable and chaetotaxy can only be inferred. Inclusion of these species in the keys demands the use of colour as a key character, despite intraspecific variability in pigmentation patterns.

Key one: general key and key to species of the Mesoconius infestus group

1. Katatergite almost always swollen ( Fig. 5E View Fig ), usually conspicuously swollen with a nipple-like apex ( Fig. 9E View Fig ); exceptions (three species of the M. eques View in CoL group with an indistinctly swollen katatergite) lack postocellar bristles ( Fig. 5B View Fig ). Outer vertical bristle absent ( Fig. 5B View Fig )..................2

– Katatergite weakly swollen and gently rounded, without a nipple-like apex ( Fig. 38D View Fig ); postocellar bristle always present. Outer vertical bristle present or absent ...........................Key three

2. Mid and hind legs uniformly orange, without bands; body entirely black to very dark brown, notum with indistinct silvery vitta ( Fig. 23A View Fig ). Wing brown, with three small clear spots distally ........................................................... Mesoconius flavipes Enderlein, 1922 ( Colombia) View in CoL

– If legs uniformly orange, then body also entirely or partly orange. Wing and notum variable....3

3. Postocellar bristle absent, upper back of head thus with only inner vertical bristle ( Fig. 3F View Fig ). Stems of paired spermathecae conspicuously multi-branched and/or spermathecal ducts sharing a common stem well beyond apex of bursa ( Fig. 3C View Fig ). Hypandrium anteriorly narrow and ribbon-like ( Fig. 6D View Fig ) .......................... Mesoconius eques View in CoL group ..........................Key two

– Postocellar and inner vertical bristles present. Stems of paired spermathecae sometimes swollen but not branched or tuberculate. Spermathecal ducts arising separately from a short distal extension of bursa ( Fig. 27C View Fig ). Hypandrium anteriorly very broad and conspicuously twisted ( Fig. 21B View Fig ) ..................................... Mesoconius infestus View in CoL group.....................................4

4. Thorax black or dark brown, at least dorsally..............................................................................5 – Thorax orange ....................................................................................................................................9

5. Hind tibia black and posteroventral part of pleuron, mid coxa and hind coxa orange.........6 – Hind tibia yellow or orange. Pleuron and coxae black.............................................................7

6. Katepisternum and part of abdominal T1 orange or red ( Fig. 22H View Fig ). Oviscape bare, shiny .............. ................................................. Mesoconius albimanus Enderlein, 1922 View in CoL ( Peru, Colombia, Bolivia)

– Katepisternum and abdominal T1 black ( Fig. 22G View Fig ). Oviscape largely setulose ................................. .......................................................................................... Mesoconius albipedis View in CoL sp. nov. ( Colombia)

7. Fore tarsus white, contrasting with bright yellow hind tarsomeres 1 and 2 ( Fig. 27A View Fig ). Hind femur black, except for orange apex ................................................... Mesoconius notacca View in CoL sp. nov. ( Peru)

– Fore tarsus yellow, similar in colour to hind tarsomeres 1 and 2. Hind femur orange with black bands ..................................................................................................................................................8

8. Sternite 8 of male (the dorsal sclerite immediately anterior to the epandrium) mostly microtrichose, shiny only on anterior quarter ( Fig. 21A View Fig ). Frontal vitta more or less diamond-shaped ( Fig. 20B View Fig ). Length about 20 mm .................................................... Mesoconius acca View in CoL sp. nov. ( Peru)

– Sternite 8 of male entirely bare and shiny ( Fig. 24B View Fig ). Frontal vitta teardrop-shaped ( Fig. 24E View Fig ). Length less than 19 mm .................................................................... Mesoconius infestus Enderlein, 1922 View in CoL ( Bolivia, Colombia, Ecuador) (possibly a species complex; highly variable in leg colour)

9. Head black ................................................ Mesoconius nigricephala View in CoL sp. nov. ( Ecuador, Colombia) – Head orange .....................................................................................................................................10

10. Mid and hind femora entirely orange ( Fig. 23C View Fig ) ...... Mesoconius fulvus Enderlein, 1922 ( Ecuador) View in CoL – Mid and hind femora with broad black bands at midlength ( Fig. 23D View Fig ).................................11

11. Fore tibia black, except for extreme apex. Frontal vitta rounded anteriorly, not sharply demarcated from lower frons ( Fig. 29D View Fig ) ........... Mesoconius ujhelyianus Enderlein, 1922 ( Colombia, Ecuador)

– Fore tibia yellow-brown. Frontal vitta distinctly triangular, upper margin tapered, and lower margin straight and forming a sharp line of demarcation between the black frontal vitta and the yellow lower frons ( Fig. 23F View Fig ) ....................... Mesoconius garleppi Enderlein, 1922 ( Peru) View in CoL

Key two: the Mesoconius eques group (outer vertical and postocellar bristles absent)

1. Katatergite conspicuously swollen, with a prominent nipple-like apex ( Fig. 16B View Fig ).....................2 – Katatergite at most slightly swollen, without a prominent nipple-like apex ( Fig. 18D View Fig )............14

2. Mid and hind leg entirely or almost entirely black, femora sometimes with narrow pale rings or with narrow reddish basal and distal parts. Body colour black or blue-black; hind tarsus never white ...................................................................................................................................................3

– No leg entirely or almost entirely black. Body colour variable, if black then hind tarsus white......5

3. Fore tarsus mostly white, first tarsomere not enlarged ( Fig. 15A View Fig ) ....................................................... ............................................................................................ Mesoconius pasachoa View in CoL sp. nov. ( Ecuador)

– Fore tarsus black, first tarsomere sometimes enlarged.....................................................................4

4. First tarsomere of fore leg of both sexes enlarged, broad and flat ( Fig. 9B View Fig ). Mid coxa with comb of black anteroventral bristles. White bands on hind femur usually distinct ...................... ................................................................. Mesoconius eques ( Schiner, 1868) View in CoL ( Ecuador, Venezuela)

– First tarsomere of females slender ( Fig. 13C View Fig ), males unknown. Mid coxa with comb of golden anteroventral bristles. Bands on mid and hind femora indistict to obsolete ................................... ................................................................................................. Mesoconius noteques View in CoL sp. nov. ( Peru)

5. Thorax entirely or mostly yellow or orange......................................................................................6 – Thorax entirely or mostly black or very dark brown........................................................................9

6. Thorax, base of abdomen and basal third of mid and hind femora orange to red, without vittae. Abdominal pleuron with black vertical stripes; tergites black ( Fig. 17A View Fig ) .......................................... ............................................................... Mesoconius rufithorax Enderlein, 1922 View in CoL ( Peru and Bolivia)

– Thorax colour not totally orange to red, notum distinctly vittate. Abdominal pleuron unmarked; tergites 3–6 usually pale or desclerotized...........................................................................................7

7. Fore tarsus (of females and known males) unmodified. Abdomen of males white, tergites pale and lightly sclerotized (males of M. cosanga View in CoL sp. nov. unknown).................8

– Fore tarsomere 1 of female greatly enlarged, wider and longer than remainder of tarsus ( Fig. 4C View Fig ). Abdomen of male dark, tergites sclerotized .............. Mesoconius anchitarsus View in CoL sp. nov. ( Venezuela)

8. Fore tarsus black. Notum with broad black vittae. Ocellar triangle elevated, orange ( Fig. 3F View Fig ) .. ..................................................................................... Mesoconius albitergum View in CoL sp. nov. ( Colombia)

– Fore tarsus white. Notum orange, with narrow golden vittae interrupted by suture ( Fig. 7C View Fig ). Ocellar triangle not elevated, mostly black ( Fig. 7A View Fig ) .......... Mesoconius cosanga View in CoL sp. nov. ( Ecuador)

9. Mid and hind femora with a pale yellow or orange band at middle, sometimes margined with darker bands....................................................................................................................................10

– Mid and hind femora without a pale band, instead either bicoloured, concolourous reddish or with darker bands ......................................................................................................................…12

10. Fore tarsus mostly yellow (base of basal tarsomere black). Mid and hind femora reddish brown, with an inconspicuous pale middle band. Abdominal pleuron pink, tergites and oviscape mostly orange ( Fig. 16E View Fig ) ......................... Mesoconius rufipleuron View in CoL sp. nov. ( Ecuador)

– Fore tarsus entirely black. Mid and hind femora orange or yellow, with a pale yellow band at middle. Abdomen darker, differently pigmented, usually part black and part yellow..................11

11. Males with cercus tapered and simple ( Fig. 6A View Fig ). Notum with two presutural and four postsutural narrow golden longitudinal vittae; katatergite prominent and orange, in contrast with otherwise mostly dark mesopleuron ( Fig. 5E View Fig ). Black preapical bands on mid and hind femora weak and narrow ( Fig. 5A View Fig ) ........................... Mesoconius auristrigatus Enderlein, 1922 View in CoL ( Ecuador, Colombia)

– Males with cercus bilobed ( Fig. 12E View Fig ). Notum with a broad median black strip flanked by broad lateral golden vittae; katatergite not contrasting with surrounding mesopleuron. Black preapical bands on mid and hind femora broad and strong ( Fig. 11D View Fig ) ................................................................ ................................................................... Mesoconius nigripleuron View in CoL sp. nov., in part ( Peru, Bolivia)

12. Katatergite orange. Mid and hind femora entirely red-orange exept for a narrow black base. Mid and hind tibiae orange ( Fig. 10A View Fig ) ........................... Mesoconius hirsutimamma View in CoL sp. nov. ( Colombia)

– Katatergite dark. Mid and hind femora yellow-red at least distally, usually with black rings or black base. Tibiae yellow to brown................................................................................................13

13. Frontal vitta with a tapered point reaching anterior margin of frons and with lateral extensions almost reaching eye. Epandrium with a pointed tuft of densely packed setae at posteroventral corner ( Fig. 8C View Fig ). Female abdominal pleuron pale ..... Mesoconius epandribarba View in CoL sp. nov. ( Colombia)

– Frontal vitta broadly rounded anteriorly, widely separated from both frons margin and eye. Epandrium without a pointed tuft of densely packed setae at posteroventral corner ( Fig. 12A View Fig ). Female abdominal pleuron darkly pigmented ( Fig. 11A View Fig ) ... Mesoconius nigripleuron View in CoL sp. nov., in part ( Peru)

14. Hind femur orange on basal half and black on distal third, with a yellow or white ring between black and orange parts; mid femur basally orange, distally black ( Fig. 14F View Fig ). Tergites 1–3 orange, distal tergites black. Males unknown. ... Mesoconius obtusiconus Enderlein, 1922 View in CoL ( Peru, Colombia)

– Mid and hind femora black with orange apices and a white central band, or femora orange with a black band near middle. Tergites uniformly coloured or darkest near base of abdomen............15

15. Mid and hind femora black with orange apices and a white central band. Male fore tarsus black, distal tarsomeres greatly enlarged ( Fig. 1B View Fig ). Female fore tarsus white basally and black distally ( Fig. 1C View Fig ). Body mostly black. Male S5 and S6 elongate, well developed. Wing uniformly pigmented ............................................................................. Mesoconius albiseta View in CoL sp. nov. ( Ecuador)

– Mid and hind femora orange with brown rings ( Fig. 19 View Fig ), basal two thirds of hind femur sometimes more extensively pigmented. Fore tarsus entirely white, male fore tarsus with apex of tarsomere 1 curved to meet an enlarged tarsomere two Fig. 19D View Fig ). Body usually mostly orange. Sternite 5 of male greatly reduced, S6 reduced to two widely separated sclerites ( Fig. 18E View Fig ). Males with wing clear, except for a dark apical spot ( Fig. 19D View Fig ), female wing uniformly yellowishclear ................................................................................ Mesoconius suzukii View in CoL sp. nov. ( Colombia)

Key three: the Mesoconius oblitus and nono groups

Species with a postocellar bristle but without a swollen katepisternum will key out here. These species are divided into the ʻ M. nono groupʼ (with an outer vertical bristle) and the ʻ M. oblitus groupʼ (without an outer vertical bristle), but the vertical bristles are often broken and can be difficult to assess. Both groups are infrequently collected, and most species are known from either a single sex, a single specimen, or from inadequate older type specimens.

1. Thorax orange to reddish brown; head entirely black.....................................................................2

– Thorax usually dark brown or black, but if orange then head similarly coloured at least on posterior half .....................................................................................................................................................6

2. Wing mostly clear, with a broad and distinct but incomplete dark discal band ( Fig. 36A View Fig ). Anterior spiracle black .................................................. Mesoconius uchumachi View in CoL sp. nov. ( Bolivia)

– Wing either uniformly pigmented, uniformly clear, or infuscated with one–three clear areas distally. Anterior spiracle orange to reddish brown...........................................................................3

3. Mid and hind femora with a white ring near the middle...............................................................4 – Mid and hind femora uniformly pigmented or black distally, without a white ring....................5

4. Basal half of mid and hind femora orange to brown, darker adjacent to white distomedian ring; distal part beyond white ring black, broad and sulcate ( Fig. 30E View Fig ) ...................................................... .................................................................................... Mesoconius scurrus ( Hennig, 1935) ( Bolivia) View in CoL

– Mid and hind femora brown, except for broad white ring near middle; distal part of hind femora neither strongly swollen nor sulcate ( Fig. 40G View Fig ) .................................................................................. ................................................... Mesoconius versicolorus ( Enderlein, 1922) View in CoL ( Colombia, Venezuela)

5. Prothorax black. Hind femur sharply bicoloured, distal half black ( Fig. 40E View Fig ) ................................... ........................................................................................ Mesoconius filipes ( Enderlein, 1922) ( Peru) View in CoL

– Prothorax brown, similar to mesothorax. Hind femur uniformly brown in typical specimens ( Fig. 40C View Fig ) ............................................................... Mesoconius cyclops ( Hennig, 1935) ( Bolivia) View in CoL

6. Thorax orange....................................................................................................................................7 – Thorax dark .....................................................................................................................................12

7. Mid and/or hind femora with basal or distomedian black rings ( Figs 33A View Fig , 38A View Fig ). Frontal vitta black ( Fig. 38C View Fig ). Outer vertical bristle present or absent................................................................8

– Mid and hind femora uniformly pigmented. Frontal vitta orange ( Fig. 31A View Fig ). Outer vertical bristle present ( Fig. 31A View Fig )...........................................................................................................................11

8. Scutellum with a pair of long apical bristles ( Fig. 38B View Fig ). Postpronotal lobe orange. Frontal vitta black, but not extending to anterior margin of frons, or entire lower frons black; flat to strongly convex ................................................................................................................................................9

– Scutellum without apical or other bristles. Thorax with a distinct black spot over postpronotal lobe ( Fig. 33A View Fig ). Frontal vitta flat, black, elongate-triangular and reaching or almost reaching anterior margin of an otherwise reddish frons ( Fig. 33F View Fig ) ........... Mesoconius garyi View in CoL sp. nov. ( Peru)

9. Mid and hind femora with distomedian rings. Fore tarsomere 1 mostly black. Frontal vitta strongly convex or lower frons black.............................................................................................10

– Hind femur with basal black ring, mid femur uniformly orange. Fore tarsus entirely yellow. Frontal vitta almost flat, black, widely separated from anterior margin of frons, lower frons orange ( Fig. 30C View Fig ) ..........................................................................................… Mesoconius ottoi View in CoL (new replacement name for M. garleppi ( Enderlein, 1922) View in CoL ; Bolivia and perhaps Colombia)

10. Outer vertical bristle present ( Fig. 38C View Fig ). Wing uniformly infuscated. Lower frons entirely black, concolourous with frontal vitta and contrasting with yellow face and antennal bases ( Fig. 38C View Fig ). Fore tarsus black distally. Hind femur with two black rings ..... Mesoconius zorro View in CoL sp. nov. ( Peru)

– Outer vertical bristle absent. Wing with distal clear areas ( Fig. 40B View Fig ). Anterior margin of frontal vitta separated from frons margin by pale area. Fore tarsus white distally. Hind femur with a single incomplete ring ...................... Mesoconius braueri ( Hennig, 1935) ( Venezuela) View in CoL

11. Mid and hind femora uniformly brown ( Fig. 30A View Fig ). Fore tarsus and tibia similarly pale brown ... ............................................................................. Mesoconius hoffmannsi ( Enderlein, 1922) ( Peru) View in CoL

– Mid and hind femora uniformly orange ( Fig. 31A View Fig ). Fore tarsomeres 2–5 white, contrasting with black fore tibia and base of tarsomere 1 ............................... Mesoconius aurantium View in CoL sp. nov. ( Peru)

12. Outer vertical bristle absent ( Fig. 48B View Fig ).......................................................................................13 – Outer vertical bristle present ( Fig. 37B View Fig ).......................................................................................25

13. Frons sharply bicoloured: lower frons, face and antennae orange to yellow, remainder of head black. Fore tarsomere 1 expanded, strongly and conspicuously so in male ( Fig. 43C View Fig ). Hind femur dark, with a reddish distomedian ring ........................ Mesoconius lobopoda View in CoL sp. nov. ( Colombia)

– Lower frons dark, not sharply contrasting with upper frons. Fore tarsomere 1 similar in diameter to tibia, not strongly flattened in either sex. Hind femur without a reddish distomedian ring.........14

14. Face and lunule yellow ( Fig. 42A View Fig ). Frontal vitta broadly reaching frontal margin. Mid and hind femora with broad basal and distal black bands, similar in length to intervening middle orange band ( Fig. 41D View Fig )................................................................................................................................15

– Face and lunule at least partially dark. Frontal vitta tapered, reaching frontal margin at most as a point. Femoral colour variable.....................................................................................................16

15. Mid and hind femoral apices orange ( Fig. 41D View Fig ). Postocellar portion of frontal vitta tapered to a narrow point; parafacial orange ( Fig. 41E View Fig ). Oviscape orange ............................................................. ............................................................................................... Mesoconius apicalis View in CoL sp. nov. ( Ecuador)

– Mid and hind femoral apices black ( Fig. 42B View Fig ). Postocellar portion of frontal vitta broad; parafacial black ( Fig. 42A View Fig ). Oviscape black .................. Mesoconius gelbifacies View in CoL sp. nov. ( Ecuador)

16. Hind femur with a broad distomedian pale ring ( Fig. 45B View Fig )......................................................18 – Hind femur with at most a narrow distomedian pale ring............................................................21

18. Frontal vitta strongly convex and dome-like ( Fig. 45E View Fig ). Epicephalon microtrichose .......................... ..................................... Mesoconius oblitus ( Hennig, 1935) View in CoL species complex ( Venezuela, Colombia) – Frontal vitta at most slightly convex, not dome-like. Epicephalon shiny....................................19

19. Body dark metallic blue ( Fig. 48A View Fig ). Mid and hind femora black with white bases and white distomedian rings. Fore and hind tarsi black ........................... Mesoconius rex View in CoL sp. nov. ( Colombia) – Body black to dark brown. Femora without white basal rings. Fore and/or hind tarsi all or mostly white .................................................................................................................................................20

20. Hind femur with pale ring between basal yellow half and distal brown third; mid femur darkened in distal third but without pale ring ( Fig. 40A View Fig ) ............................................................... ........................................................................... Mesoconius afurcatus ( Hennig, 1935) ( Venezuela) View in CoL

– Mid and hind femur dark basally and distally and with a broad pale ring at middle ( Fig. 42E View Fig ) .. .................................................................................................. Mesoconius keili View in CoL sp. nov. ( Ecuador)

21. Abdomen all or mostly reddish or orange. Mid and hind femora orange, with or without darker rings .................................................................................................................................................22

– Abdomen all or mostly black or metallic blue-black. Mid and hind femora mostly black, sometimes with paler rings.....................................................................................................................23

22. Mid and hind femora orange with indistinct distomedian rings. Scutellum brown. Wing lightly infuscated, with clear distal areas ( Fig. 40F View Fig ) .. Mesoconius rufiventris ( Enderlein, 1922) ( Colombia) View in CoL

– Mid and hind femora orange, without distomedian rings. Scutellum orange. Wing heavily and evenly infuscated, yellow, without clear distal areas ( Fig. 49D View Fig ) ...... Mesoconius ruficrus View in CoL sp. nov. ( Peru)

23. Hind femur with an indistinct reddish mediodistal ring, femora otherwise black. Wing with clear distal patches ( Fig. 41A View Fig ) ............................................................. Mesoconius apa View in CoL sp. nov. ( Bolivia)

– Mid and hind femur with white distomedian ring. Wing darkly infuscated, without clear patches ..........................................................................................................................................24

24. Inner vertical and postocellar bristles greatly reduced, barely distinguishable from surrounding setulae ( Fig. 47A View Fig ) ................................................................ Mesoconius quadritheca View in CoL sp. nov. ( Peru)

– Inner vertical and postocellar bristles large, distinct ( Fig. 44A View Fig ) ..................................................... .................................................................................................. Mesoconius nigra View in CoL sp. nov. ( Bolivia)

25. Thorax sharply bicoloured: notum black, balance of thorax entirely yellow ( Fig. 37A View Fig ). First abdominal tergite and base of T2 entirely yellow to orange, abdomen otherwise black ................... .............................................................................................. Mesoconius wytkowskii sp. nov. ( Peru)

– Neither thorax nor abdomen sharply bicoloured...........................................................................26

26. Thorax and abdomen entirely black or metallic blue...............................................................27 – Thorax partially black, but with orange or reddish-brown patches at least on pleuron; abdominal tergites orange (females) or brown (males) ( Fig. 32 View Fig ) .... Mesoconius bipleuron View in CoL sp. nov. ( Colombia)

27. Thorax and abdomen black, notum silvery microtrichose, except for broad central strip ( Fig. 34A View Fig ). Legs variable in colour, but hind femora either uniform in colour or with basal half dark. Abdominal pleuron dark ...................................................... Mesoconius nono View in CoL sp. nov. ( Ecuador)

– Thorax and abdominal tergites metallic blue with light pruinosity. Mid and hind femora black, with broad white distomedian bands ( Fig. 35A View Fig ). Abdominal pleuron white, except for upper part of P2 ......................................................................... Mesoconius reinai View in CoL sp. nov. ( Colombia)

Species descriptions

The species treatments below are in alphabetical order within each of four groups: the M. eques group, the M. infestus group, the M. nono group and the M. oblitus group. The latter two, loosely equivalent to ʻ Zelatractodes ʼ of previous authors, are weakly supported groups diagnosed on the presence ( M. nono group) or absence ( M. oblitus group) of outer vertical bristles. Species descriptions are prefaced with a brief summary of readily visible colour characters, followed by descriptions of the head, thorax and abdomen. Previously described species known only from undissected type material are briefly diagnosed rather than redescribed. Previously described species known from undissected type material as well as dissected non-type material are redescribed based in part on the dissected non-type material.

Kingdom

Animalia

Phylum

Arthropoda

Class

Insecta

Order

Diptera

Family

Micropezidae

Loc

Mesoconius Enderlein, 1922

Marshall, Stephen A. 2019
2019
Loc

Aristobata

Steyskal 1968: 5
Frey 1927: 5
Frey 1927: 5
Enderlein 1922: 5
1927
Loc

Mesoconius

Enderlein 1922: 4
Enderlein 1922: 4
1922
Loc

Zelatractodes

Marshall 2015: 5
Enderlein 1922: 5
Enderlein 1922: 5
1922
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