Genus Achradocera Becker, 1922

Achradocera Becker, 1922: 207 (Figs 78, 79).

Type species: Achradocera femoralis Becker, 1922

(but see discussion under species description). Subsequent designation by Robinson (1970, treated as subgenus of Chrysotus) [Robinson (1975) and subsequent works recognized Achradocera as a valid genus].

Error: Accradocera (Vanschuytbroeck, 1952: 6, 11), Acradocera (Vanschuytbroeck, 1951: 74, 128), Acrodocera (Lamb, 1933: 113, 72).

Diagnosis. Postpedicel (Fig. 1B–D) enlarged, with broad base constricted into short or long narrow tip; arista-like stylus subapical (MSSC); lower postoccipital setae multiseriate and flattened, forming prominent, stiff white “beard” (MSSC); FI and FII mostly yellow, usually with dark brown line on dorsal surface; FIII wholly dark brown to metallic green (color of femora is the main diagnosis for females); males of some species with modified structures on tarsomeres, TII and/or FIII; phallus with dorsal saw-like or lump-like grooves; lateral epandrial lobe appressed to base of surstylus.

Description. Small to medium sized (1.5–3.0 mm), metallic green with bronze, blue and/or violet reflections. Head. Face narrow (MSSC); front broad, diverging above; scape and pedicel black and short; male postpedicel (Fig. 1B–D) enlarged, with broad base constricted into short or long narrow tip; arista-like stylus subapical; lower postoccipital setae multiseriate and flattened, forming prominent, stiff white “beard” in male (Fig. 1A); female postpedicel short and rounded, bearing long apical arista-like stylus. Thorax. Mesonotum posteriorly rounded; ac short, biseriate; 5 pairs of distinct strong dc, decreasing in size anteriorly; scutellum with pair of setae and pair of small setae laterad. Wing (Fig. 4C). Membrane hyaline, veins brown. Costa ending at M 1 near wing apex; R 1 ending at 2/5 of wing length, R 4+5 and M 1 parallel to apex, with M 1 ending at wing apex. M 4 not reaching wing margin; lower calypter with fan of brownish setae; halter white or pale yellow. Legs. Mostly yellow, except coxae, dorsal surface of FI, FIII and last segments of tarsi brown to metallic green; FII sometimes dorsally infuscated and tibiae rusty yellow; TI, It 1–2, TII, IIt 1, FIII and IIIt 2–4 may show conspicuous modifications in male (e.g. excavations, special setae, projections). Abdomen. Usually about as long as thorax; sternites 1 and 2 with white setae. Hypopygium (Figs 10A–D, 23A–D). Dark brown with brownish cercus; Epandrium circular; phallus with dorsal saw-like or lump-like grooves; lateral epandrial lobe appressed to base of surstylus; surstylus with 2 strong, horn-like setae; cercus small and rounded; postgonite covered with short setae, projecting two ventral arms (hypandrial apodeme), and dorsally connected with base of phallus; ejaculatory apodeme straight and digitiform. Female terminalia (Fig. 24A, B). Anterior margin of tergites 6–7 with deep inverted U-shaped incision. Tergite 8 rod-like and sternite 8 laterally Y-shaped, sternite 8 connected ventrally by sclerotized bridge; dorsal surface of acantophorites (tergite 9+10) with crest of about 5 rhomboid spines and 1 lateral seta; cercus membranous; sternite 10 bowl-like, with rugose and bulged membrane below.

Terminalia Variation. Minimal variations in the size and enlargement of the structures in male and female terminalia may be observed as interspecific variations and should not be considered diagnostic characters. Other small setae are often seen near the apex, displaying an irregular pattern among the species.

Identification key to the species of the genus Achradocera [adult males]

1 It 1 slightly broadened apically, bearing ventral row of distinct setae; It 2 as long as It 3, bulged and squared (Fig. 9D); hypopygium large; surstylus subrectangular, bearing 1 strong apicoventral bristle; apex folded up, with thumb-like bulged seta (Figs 7A–D, 10A–D)............................................................................................. 2

- It 1–2 simple; hypopygium small; surstylus subtriangular, tapered and bearing 1 apical and 1 subapical, strong horn-like seta (e.g., Fig. 3A)............................................................................................. 3

2 FIII with ventral protuberance at basal 1/4 bearing conspicuous setae (Figs 6A–C) [West North America]................................................................................................. A. arcuata (Van Duzee)

- FIII simple (Fig. 9A) [East North America]................................................... A. barbata (Loew)

3 Legs with modified TII and/or FIII (i.e., with excavation, notch, bulge, specialized setae or protrusion) (e.g., Fig. 11B, C).. 4

- Legs without conspicuous modifications on TII and/or FIII .................................................... 8

4 FIII simple, without major setae; TII arched at middle and bearing some strong setae on apical 1/4 of ventral surface (Fig. 17D); IIt 1 and IIIt 3–4 simple [South America: Argentina, Brazil, and Paraguay]............................ A. insignis Parent

- FIII bulged, concave posteriorly, bearing cluster of long setae at middle of anterior surface (Figs 20G, 22D); TII with conspicuous ventral excavation near middle, sometimes with strong black setae basal and/or apical to excavation (Figs 11B, 13E, 20E, 22E); IIt 1 arched, with ring of setae at basal 1/3 and anteroventral tubercule within ring; IIIt 3–4 concave (Fig. 20D)............. 5

5 Basal half or more of FI–II dark brown, apex yellow......................................................... 6

- FI–II entirely yellow with infuscate patch only on dorsal surface (FII sometimes entirely yellow, without infuscation)...... 7

6 TI entirely yellow; FIII with row of short, stout ventral setae near base, close to medial cluster of long setae (Fig. 22D) [South America, East side of Andes]...................................................... A. tuberculata (Van Duzee)

- TI with mid and apical brown infuscation (Fig. 20C); FIII with medial cluster of long setae, but without short, stout ventral setae near base (Fig. 20G) [Central and South America, West side of Andes]......................... A. meridionalis Becker

7 TI slightly bent and brownish infuscation at apical 3/4 (Fig. 11B); TII yellow with brownish dorsal infuscation at apical half; FII yellow with brownish dorsal infuscation, brown area larger basally [West Indies, Greater Antilles]................................................................................................... A. excavata (Van Duzee)

- TI straight and entirely yellow; TII entirely yellow; FII entirely yellow (Fig. 13D) [South America: Colombia and Curaçao]...................................................................................... A. femoralis Becker

8 Leg III with one or more arched tarsomeres (Fig. 8E)......................................................... 9

- Leg III with straight tarsomeres (Fig. 15A)................................................................ 10

9 Postpedicel shorter than arista-like stylus (Fig. 8B); IIIt 2 arched (Fig. 8E); IIIt 3–4 straight [South America: Brazil]................................................................................................. A. balin sp. nov.

- Postpedicel longer than arista-like stylus (Fig. 2C); IIIt 2 straight; IIIt 3–4 concave (Fig. 2B) [South America: Chile]................................................................................... A. angustifacies Becker stat. rev.

10 Postpedicel quite shorter than arista-like stylus (Fig. 4D) [West Indies, Lesser Antilles].............. A. apicalis (Aldrich)

- Postpedicel longer than arista-like stylus (Fig. 13A, B)....................................................... 11

11 Lower postoccipital setae dense (Fig. 15B); tibiae rusty yellow and FII with brownish infuscation on dorsal surface (Fig. 15A); face metallic green, without coppery reflections [South America: Brazil]............................. A. gimli sp. nov.

- Lower postoccipital setae sparse (Fig. 19B); tibiae and FII wholly yellow (Fig. 19A); face metallic green with evident coppery reflections (Fig. 19C) [South America: Argentina]............................................ A. longiseta Parent