Chrysotus robustus (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 : 54-57

Chrysotus robustus (Robinson) , comb.nov.

( Figs. 9–10 , 21 )

Diaphorus robustus Robinson, 1975: 94 .

Diagnosis. Male: Eyes approximate but not contiguous above antennae; vt absent; femora mainly brown, except apically; 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 crease; arms of postgonite with few microtrichia proximally; male cercus subtriangular.

Type material examined. DOMINICA, Clarke Hall. Holotype, 1 ɗ, 20.ii.1964, H. Robinson, leg.; Paratypes, same data of holotype, but 2 ɗ, 29.i.1964; 1 Ψ, 19.ii.1964; 1 ɗ, 20.ii.1964 ( USNM).

Re-description. Male. Body length: 3.3–4.6 mm. Wing: 3.3–4.2 mm long, 0.9–1.6 mm wide. Head. Dichoptic, frons converging at middle, as wide as ocellar mound, becoming wider above and below (mssc), metallic green, with some bluish reflections; face as broad as broadest width of frons, metallic green, with some bluish reflections, covered by silvery pruinosity, sometimes with few, not conspicuous, scattered pale setae; palpus yellow, with some brownish setae; proboscis brown with many pale setae; 1 pair of strong, 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, clearly pubescent, stylus apical, bi-articulated at base, also pubescent. Thorax. Shining green. Bluish reflections on mesonotum, scutellum and anepisternum (sometimes also katepisternum); bronze reflections on notopleuron and katepisternum; pleura slightly covered by silvery pruinosity. Ac irregularly biseriate, extending to between 4th and 5th pairs of dc; 6 pairs of long dc, except 1st pair short; 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 only few setulae on each side of median suture; 3 pprn, 1 very strong and 2 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 1 pair smaller laterad, about 1/3 as long as medial scutellars. Wing ( Fig. 21 ). Membrane somewhat infuscate along anterior margin. C ending slightly beyond wing apex; R1 ending before basal fourth of wing; R2+3 not bent anteriorly at distal end; R4+5 and M parallel, curving backwards at level of R2+3; CuAx ratio, 0.7; A1 present, not reaching wing margin; anal angle slightly enlarged. Lower calypter and cilia yellowish; halter yellow. Legs. I: 2.7, 2.7, 1.8, 0.8, 0.5, 0.3, 0.2. II: 2.9, 3.2, 2.0, 1.0, 0.7, 0.3, 0.2. III: 3.7, 4.0, 1.2, 1.0, 0.7, 0.3, 0.2. Coxae brown (except tip of CxI), trochanters and femora (except apical 1/3–1/4 of FI and FII and tip of FIII), with slight green shine; apical 1/4 of TIII and tarsi, except bases of tarsi I and tarsi II, brown; apex of CxI, apical 1/3–1/4 of FI and FII and tip of FIII, tibiae, except apical 1/4 of TIII, and base of tarsi I and tarsi II yellow. Anterior surface of CxI covered by many long pale setae and few brownish setae on distal half, outer edge with black setae; anterior surface of CxII with 1 conspicuous lateral seta at base and with diagonal row of black setae descendent internally; CxIII laterally with 1 long, black basal seta and 1 minute pale seta apically. FI with row of 5–8 pv on apical third and some erect ventral scattered setae; FII with 2–3 pv more conspicuous at apex; FIII with 1 av more conspicuous at apex. TI with 1 minute ad at base, ventral surface with short serration; TII with 1 large ad at base, 1 short ad to dorsal seta near middle, 1 ventral seta at middle; TIII with irregular row of dorsal setae, 2 ad and 3–4 pd larger. Apical tibial setae: 0, 4, 4. Pulvilli slightly developed, as long as t5 on I and II; claws present in all legs. Abdomen. Shining green, with some bluish reflection dorsally on Tg3–5, and bronze reflection laterally on Tg5. Tergites covered by long black bristles, distal margins with clearly stronger bristles. St2–4 covered by long pale setae, St4–5 also with few black setae. St8 with only pale setae on distal margin. Hypopygium ( Figs. 9–10 ). Anterior margin of epandrium straight at level of emergence of hypandrium; lateral epandrial lobe slightly projected, bearing 2 setae, basiventral seta present; surstylus short, dorsal surface with crease, 2 strong spines and 1 setae medially at apex, 1 dorsal seta near middle. Proximal portion of hypandrium with short projection; dorsal surface of distal portion serrate after emerging from epandrium. Arms of postgonite slightly longer than anterior processes and with few microtrichia proximally. Cercus short, subtriangular, pale brown. Female. Body length: 3.3 mm. Wing: 3.4 mm long, 1.2 mm wide. Very similar to males, except as noted. Frons as broad as face, about 1.5 times as high as broad, clypeal suture evident; palpus dark, yellow at apex. Legs: I: 2.5, 2.5; 1.3, 0.6, 0.4, 0.2, 0.2. II: 2.8, 3.0, 1.7, 0.8. 0.4, 0.2, 0.1. III: 3.2, 3.4, 1.1, 0.9, 0.5, 0.2, 0.2. Anterior surface of CxI with pale setae only; FI without row of pv or ventral setae; TII with 1 large ad at base, 3 dorsal and 1 ad seta near middle; pulvilli not developed. Terminalia. Similar to C. angustifrons .

Comments. This species is very similar to C. wirthi and is distinguished from the latter by the mainly brown or greenish CxI and FI (mainly yellow in C. wirthi ), and by the surstylus: surstylar seta and arm of postgonite longer in C. wirthi than in C. robustus .

Figures

FIGURES 9 – 10. Chrysotus robustus (Robinson) comb. nov., paratype, male hypopygium (9, ventral view; 10, 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.