Chrysotus wirthi (Robinson) Robinson, 2010

Capellari, Renato Soares & Amorim, Dalton De Souza, 2010, Re-description and new combination of five New World species of Chrysotus Meigen, with comments on the Neotropical genus Lyroneurus Loew (Diptera: Dolichopodidae), Zootaxa 2520, pp. 49-65 : 60-62

Chrysotus wirthi (Robinson) , comb.nov.

( Figs. 16–17 , 23 )

Diaphorus wirthi Robinson, 1975: 94 .

Diagnosis. Male: Eyes approximate above antennae, but not contiguous; vt absent; FI and apical half of FII yellow; pulvilli I and II as long as t5, claws present; abdominal sternites with long vestiture, St8 without striking bristles. Dorsal surface of surstylus with a long apical seta; arms of postgonite ca. 3 times longer than anterior proccesses.

Material examined. DOMINICA, Clarke Hall, holotype, 1 ɗ, 21–31.iii.1965, W.W. Wirth, leg. ( USNM). Paratype, 1 ɗ, 12–17.xi.1964, P.J. Spangler, leg. ( USNM).

Re-description. Male. Body length: 3.8–4.3mm. Wing: 2.2–3.8 mm long, 1.2––1.6 mm wide. Head. Dichoptic, frons converging at middle, same width as ocellar mound, becoming wider above and below, metallic green; face slightly broader than broadest width of frons, shining gray, bluish; palpus yellow, with some brownish setae; proboscis brown with many pale setae; 1 pair of strong, slightly divergent oc and 1 pair of minute poc; vt absent, 1 pair of pavt; row of pale pocl, dorsal 8–11 dark, occiput slightly concave, lower surface with many long scattered pale setae. Antenna brown, scape conical, short; pedicel short, with crown of setulae at apex, dorsalmost longer; postpedicel rectangular to trapezoidal, clearly pubescent, ventral half slightly projected, stylus apical, pubescent, bi-articulated at base. Thorax. Shining green. Dorsum of mesonotum, anepisternum and scutellum with bluish reflections; notopleuron around transverse suture and katepisternum with bronze reflections; pleura covered by silvery pruinosity. Ac irregularly biseriate, extending to 6th of 8 pairs of dc (in holotype; apparently 6 pairs of dc in paratype, but thorax damaged by pin); dc not perfectly symmetrical; 1 pre- and 1 sutural ia; 1 pre- and 2 post-sutural sa; 1 large pa with 1 minute anterior seta; 2 npl; anterior end of mesonotum with some scattered short setae on each side of median suture; 4 pprn (in holotype; 3 in paratype), 1 very strong and 3 minute; lower surface of proepisternum with 2–3 pale setae, ventralmost longer; upper surface of proepisternum in front of anterior spiracle bare; scutellum light green, with pair of strong medial scutellars and 2 pairs smaller laterad, about half as long as medial scutellars. Wing ( Fig. 23 ). Membrane hyaline. C ending slightly beyond wing apex; R1 ending on basal fourth of wing; R2+3 not bent anteriorly at distal end; R4+5 and M parallel, curving slightly backwards at level of R2+3; CuAx ratio, 0.5; A1 present, not reaching wing margin; anal angle slightly enlarged. Lower calypter and cilia yellowish; halter yellow. Legs. I: 2.6, 2.8, 1.1, 0.9, 0.5, 0.4, 0.2. II: 3.1, 3.3, 1.9, 1.0, 0.5, 0.3, 0.2. III: 3.6, 3.8, 1.1, 0.9, 0.5, 0.3, 0.2. Brown coxae (except apical 3/4 of CxI), trochanters, basal half of FII, FIII except tip, apex of TIII and tarsi except bases of tarsi I and II; apical 3/4 of CxI, FI, apical half of FII, tip of FIII, tibiae (except apex of TIII), and bases of tarsus I and tarsus II yellow; basal half of dorsal surface of FI slightly infuscate. Anterior surface of CxI covered by pale setae, distal half and outer edge with brownish setae; anterior surface of CxII with 1 conspicuous lateral seta at base and with diagonal row of black setae descendent internally; lateral of CxIII with 1 long black basal seta and 1 minute pale seta apically. FI with row of 4–6 pv on apical third; FIII with 1–2 anterior setae more conspicuous at apex. TI with 1 minute ad at base, ventral surface with short serration; TII with 1 large ad and 2–3 smaller dorsal setae, 1 near base and 2 near middle; TIII with 2 ad and row of indistinct pd, 5–7 larger. Apical tibial setae: 0, 4, 4. Pulvilli slightly developed, as long as t 5 in I and II; claws present in all legs. Abdomen. Shining green, with slight bluish reflections dorsally on Tg2–3, bronze reflections on Tg4–6. Tergites covered by long black bristles, those on distal margin longer. St2–4 covered by long pale setae, St4–5 also with few black setae. St8 only with pale setae on distal margin. Hypopygium ( Figs. 16–17 ). Anterior margin of epandrium straight at level of emergence of hypandrium; lateral epandrial lobe slightly projected, bearing 2–3 setae, basiventral seta present; surstylus elongate, two strong spines and 1 seta medially, 1 long dorsal seta apically. Proximal portion of hypandrium with short projection; dorsal surface of distal portion serrate, after emerging from epandrium. Arms of postgonite ca. 3 times longer than anterior proccesses. Cercus elongate, subtriangular, pale brown. Female. Unknown.

Comments. Similar to C. robustus , but can be distinguished from it as noted above. The original description of Robinson (1975) does not mention the asymmetrical rows of dc, neither the presence of four postpronotal setae in the holotype (not visible in the paratype). This may be teratogenic, so examination of more material may resolve this question.

Figures

FIGURES 16 – 17. Chrysotus wirthi (Robinson) comb. nov., paratype, male hypopygium (16, ventral view; 17, left lateral view). Scale bar: 0.1 mm.

FIGURES 18 – 25. Wings of Chrysotus and Lyroneurus. 18. C. angustifrons (Robinson) comb. nov., male paratype. 19 – 20. C. maculatus (Parent) comb. nov. (= Diaphorus maculipennis Robinson) (19, male; 20, female). 21. C. robustus (Robinson) comb. nov., male paratype. 22. C. spectabilis (Loew), male. 23. C. wirthi (Robinson) comb. nov., male paratype. 24 – 25. L. adustus (Wiedemann), male. Scale bars: 1.0 mm.