Achradocera barbata (Loew, 1861)

(Figs 1A–C, 9, 10, 26)

Synarthus barbatus Loew, 1861: 138 .

Type-locality: “Middle States” of USA. Transferred to Chrysotus by Aldrich, 1902: 90. Holotype male, MCZ .

Chrysotus validus Loew, 1861: 68 (described from a female). Type-locality: both described from “Middle States” of USA. Synonymized with Chrysotus barbatus by Aldrich, 1902: 90. Holotype female, MCZ.

Xiphandrium americanum Wheeler, 1896: 154 . Type-locality: USA: Wisconsin, Milwaukee; Illinois, Chicago; Indiana, Whiting. Synonymized with Chrysotus barbatus by Wheeler, 1899: 37. Syntypes male and female, AMNH.

Diagnosis (male). Postpedicel longer than arista-like stylus; lower postcranial setae dense. Legs mostly yellow, except for FIII, dorsal surface of FI and FII, TIII at basal 1/4 and apical 1/5, and distal tarsi, which are all brown infuscated; It 1 slightly broad apically, bearing ventral row of distinct setae; It 2 as long as It 3, bulged and squared; mid and hind legs simple. Hypopygium large; surstylus subrectangular, bearing 1 strong apicoventral bristle; apex folded up, with thumb-like bulged seta, rounded by small setulae basally; postgonite reduced, with anterior side fissured and bearing some small setula.

Redescription. Similar to A. angustifacies stat. rev., except as noted. Male. Body length: 2.5–2.7 mm. Wing: 2.2–2.4 mm long, 0.7–0.8 mm wide. Antenna. Postpedicel (Fig. 9, C) longer than arista-like stylus (MSSC); FAr ratio, 2.6. Thorax. 6–8 ac, and 5 dc pairs of setae. Wing. CuAx: 0.6; RMx: 1.65. Leg I. 35, 30, 15, 4, 5, 4, 4. Tarsomere 1 slightly broad apically, bearing ventral row of distinct setae (MSSC); t 2 about same length as t 3, bulged and squared (MSSC). Leg II. 40, 45, 20, 8, 5, 4, 3. F brown infuscated dorsally, but infuscation weaker than FI; T with anterior seta at basal 1/4 and 4 setae at apex (1 ad, 1 pd, 1 av and 1 pv). Leg III. 38, 42, 13, 9, 5, 4, 3. F with metallic green reflections; T bearing 3 pd at basal 2/3, 2 ad on basal half and 4 apical setae (1 v, 1 d, 1 ad and 1 av). Abdomen. Longer than head plus thorax length; sternite 5 with distinct setae posteriorly. Hypopygium (Fig. 10A–D). Long, dark brown with brown cercus; epandrium circular; epandrial lobe appressed and bearing some small hair-like setae; foramen rounded; surstylus suture not evident; phallus dorsally serrate on apical half, slightly bulged at mid-length; surstylus subrectangular, bearing 1 strong apicoventral seta; apex folded up, with thumb-like expanded seta, surrounded by small setulae basally, and small apicodorsal seta; cercus longer than wide, with setae as figured; postgonite reduced, with anterior side fissured and bearing some small setulae, carrying two enlarged posterior arms (hypandrium apodeme) and dorsal projection connected to basiphallus; ejaculatory apodeme digitiform, long and straight.

Female. Similar to males, except by MSSC and as noted. Body length: 2.6–2.67 mm. Wing: 2.7–2.76 mm long, 0.98–1.04 mm wide. Terminalia. As in generic description (similar to Fig. 24).

Distribution. Eastern Canada and eastern USA (Fig. 26).

Wisconsin. 1♂, “PotatoLake | 9/7/33 WISC | ALMelander”, “ALMelander | Collection | 1961”. [Most specimens housed in USNM, except specimens collected by J. Runyon and/or R. Hurley, housed in MTEC and the Canadian specimen, housed in CNC] .

Remarks. Previously, A. barbata was traditionally considered as a species with a broad range distribution in the New World, reaching Tonga French Polynesia (likely dispersed to Hawaii by accidental human introduction; see Bickel 2000). Despite the historic misleads regarding the taxonomy of A. barbata, Runyon (2020) clarified its identity, and the species was straightforward recognized by the features mentioned in the comparative diagnoses of the species. After an extensive survey, the distribution range of A. barbata is now well-defined and restricted to eastern North America.