Achradocera arcuata (Van Duzee, 1924)

(Figs 6, 7, 26)

Chrysotus arcuatus Van Duzee, 1924: 48, figs 17–18.

Type-locality: Alpine, San Diego Co., California. Holotype male, USNM .

Diagnosis (male). Postpedicel longer than arista-like stylus; lower postoccipital 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 broadened apically, bearing a ventral row of distinct setae; It 2 as long as It 3, bulged and squared; leg II simple; FIII bearing a ventral protuberance at basal 1/4 bearing conspicuous setae. Hypopygium large; surstylus subrectangular, bearing 1 strong apicoventral seta; apex folded up, with a thumb-like bulged seta, surrounded by small setulae basally; postgonite reduced, with anterior side fissured and bearing some small setulae.

Redescription. Similar to A. angustifacies stat. rev., except as noted. Male. Body length: 2.7–2.8 mm. Wing: 2.4–2.5 mm long, 0.75–0.85 mm wide. Antenna. Postpedicel (Fig. 6D) longer than arista-like stylus (MSSC); FAr ratio, 1.18. Thorax. About 8 pairs of ac setae. Wing. CuAx: 0.65; RMx: 1.4; lower calypter yellow with fan bearing about 10 brownish setae. Leg I. 33, 27, 13, 4, 5, 3, 3. Tarsomere 1 slightly broadened apically, bearing ventral row of distinct setae (MSSC); It 2 about same length as It 3, bulged and squared (MSSC). Leg II. 28, 38, 13, 7, 4, 3, 3. T with anterior seta at basal 1/4 and 4 setae apically (1 a, 1 ad, 1 av, and 1 p). Leg III. 35, 38, 15, 9, 4, 3, 3. F with metallic green reflections, bearing ventral protuberance at basal 1/4, bearing conspicuous setae; T with 4 pd, 3 ad, and 4 apical setae (1 v, 1 d, 1 ad and 1 av) (MSSC). Abdomen. Longer than thorax length; sternite 5 bearing strong posterior setae. Hypopygium (Fig. 7A–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 preapical mid-length; surstylus subrectangular, bearing 1 strong apicoventral seta; apex folded up, with thumb-like bulged 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 with basiphallus; ejaculatory apodeme digitiform, long and straight.

Female. Similar to males, except by MSSC and as noted. Body length: 2.55–2.6 mm. Wing: 2.55–2.63 mm long, 0.93–0.98 mm wide. Terminalia. As in generic description (Fig. 24).

Distribution. Western USA [and Hawaii, probably introduced] and Mexico (Fig. 26).

Type material examined. PARATYPE 1♂, labelled: “ Alpine, Cal. | Apr. 8 ’15 | MCVanDuzee”, “Collection | J M Aldrich ”, “PARATYPE”, “ Chrysotus arcuatus V. D. [handwritten]” [USNM] .

Remarks. In general, A. arcuata is a readily recognizable species, primarily due to the unique modification in FIII. Its geographic distribution (Fig. 26) is extensive, yet apparently well-defined. However, it is interesting to note the record for Mexico, which may suggest that A. arcuata also occurs in the Neotropics. Nonetheless, this locality is at a high altitude (approximately 2,240 m), still exhibiting Nearctic traits.