Empis angustipennis Bezzi, 1909

Rafael, J. A. & Câmara, J. T., 2012, Revision of Neotropical species of Empididae (Diptera) described by Mario Bezzi. XI. The species described in Empis Linnaeus, Zootaxa 3488, pp. 63-79 : 64-66

Empis angustipennis Bezzi

( Figs. 1 – 11, 78)

Empis angustipennis Bezzi, 1909: 351 ; Melander, 1928: 147 (checklist); Collin, 1933: 231 (citation); Smith, 1967: 21 (catalogue); Yang et al., 2007: 130 (catalogue).

Diagnosis. Dark brown to black, subshiny; proboscis 2X head height; scutum with faint dark stripes visible in certain angles; acrostichals present; legs dark yellow basally, brown after femora; fore tarsomere 1 slightly wider than apex of tibia and around 0.8X length of fore tibia; wing brown, long and narrow; female cercus elongate.

Re-description. Lectotype female. Body length 5.0 mm; wing length 5.7 mm. Dichoptic. Frons ( Fig. 3) shiny black in dorsal view, grey pruinescent between small setae, with 4 pairs of small lateral proclinate setae, wider than ocellar tubercle, roughly 1.5X higher than wide. Ocellar tubercle shiny black, pruinescent posteriorly, with divergent anterior setae and 5–6 small posterior setae (not represented in figure). Ocellus glassy, yellow. Face ( Fig. 4) bare, shiny black, protuberant at apex ( Fig. 1), with inverted U-shaped grey pruinescent spot (better seen in dorsal view ( Fig. 4)). Postcranium ( Fig. 2) dark brown to black, grey pruinescent, with uniserial postocular and occipital setae; vertical and occipital setae stouter and longer than postocular row. Gena with small slender setae, postgena with slightly stronger setae. Scape and pedicel yellow to light brown, with small black setae and sparsely grey pruinescent; postpedicel missing. Proboscis ( Fig. 1) 2X head height; labrum shiny yellow; labium dark brown. Palpus hidden, brown.

Thorax ( Fig. 5) dark brown to black, except postpronotal lobe, postalar callus, scutellum, laterotergite and pleural sutures with marginal yellow tones. Thorax with fine grey pruinescence visible at certain angles. Scutum with 3 rather inconspicuous velvety matte-black stripes, extending slightly beyond transverse suture, one medially under acrostichal row and paramedian pair under dorsocentral rows. Chaetotaxy: 4–5 distinct antepronotals; 1 strong and 3–4 slender postpronotals; 1 strong and 2–3 slender proepimerals; 5–6 small uniserial acrostichals, last pair after transverse suture; roughly 7 misaligned dorsocentrals, apparently uniserial; 1 presutural intra-alar; 1 postsutural intraalar; 1 presutural supra-alar; 1 postsutural supra-alar; 4 notopleurals; 1 postalar; 2 pairs of scutellars, the apical pair longer and crossed; 15–17 laterotergitals, anterior row fan-like, with stout setae, longer than halter.

Legs setulose, dark yellow basally, brown after femora. Hind coxa smaller, thicker than fore and mid coxae. Foreleg ( Fig. 6): tibia with series of 6 equidistant anterodorsal and posterodorsal setae, besides 2 anteroventral, 1 submedian and 1 apical; 1 posteroventral, 1 anterior and posterior apicals, latter two weaker; tarsomere 1 slightly wider than tibia, almost as long as respective tibia, with series of 3 anterodorsals, 3 equidistant posterodorsals and 1 anterior and posterior subbasal, 1 anterior, 1 posterior, 1 anteroventral and posteroventral apical setae; remaining tarsomeres, except last, with 1 anteroventral and 1 posteroventral more stronger than background setae. Midleg ( Fig. 7): femur with small spiniform anteroventral and posteroventral setae on basal 0.33, posterior row shorter; tibia with row of 5 longer, equidistant anterodorsal and posterodorsal setae, 4 anteroventral equidistant setae on distal 0.67 and posteroventral row of short setae, slightly longer than background setae; tarsomere 1 with 4 anteroventral, 4 posteroventral equidistant setae, 1 ventral subbasal, 1 anterior, 1 posterior, 1 anterodorsal and 1 subapical posterodorsal, latter two weaker, other tarsomeres same as anterior pair. Hindleg ( Fig. 8): femur with 2–3 stouter apical anterodorsal setae; tibia with row of 7 – 8 equidistant anterodorsal and posterodorsal setae; 3 equidistant anteroventral setae on distal half, 2 posteroventrals, 1 median and 1 apical; tarsomere 1 with 2 anterodorsal, 2 posterodorsal on distal half, 1 anterior, 1 posterior apical, 2 anteroventral on distal third and 1 ventral subbasal; remaining tarsomeres same as anterior pair.

Wing ( Fig. 78) light brown, narrow and long, pterostigma inconspicuous; costal vein with 1 robust basal seta. Vein R 1 bare dorsally, slightly wider at apex. Halter with stem yellow, capitulum dark brown.

Abdomen brown, subshiny, with fine grey pruinescence visible at certain angles; setae short, lateral setae of tergite 1 distinctly longer. Sternites with same color as tergites.

Terminalia in lateral view as in Figure 9. Tergites 7 and 10 with distinct basal sinus ( Fig. 10); sternite 7 with narrow, more sclerotized longitudinal median line ( Fig. 11); tergite 8 with sclerotized area at base with medial projection extending to middle of tergite ( Fig. 10); sternite 8 sclerotized basally and laterally, membranous medially ( Fig. 11); genital fork ( Fig. 11) with arms V-shaped; cercus elongate, cylindrical.

Male. Unknown.

Geographical distribution. Peru.

Material examined. LECTOTYPE ♀ (here designated), “ PERU, Umahuankilia , Urubambafl. [= Urubamba river], 19.ix.1903)” (SMT) ; PARALECTOTYPE ♀, same data, except 13.ix.1903 (SMT) .

Lectotype condition. Postpedicel lost. Left wing on microslide. Basal abdominal sternites damaged by pests; terminalia in microvial with glycerin.

Remarks. This species was described based on three female specimens from the same locality. The paralectotype is with less distinct yellow tones on the postpronotal lobe and postalar callus.

Discussion. The female specimens of Empis angustipennis were identified as part of group II in Collin’s (1933) key through the following couplets: (1) “numerous acrostichals present, and more than 3–4 pairs of dorsocentrals”; (5) “subcostal vein (= vein R 1) entirely bare above, face bare, seldom with more than 2–3 small hairs above mouth-edge”; (13) “last tarsal joint normal, with overhanging hairs at tip”; (14) “no even comb of hairs at tip of front tibiae, but a few bristly hairs of mixed lengths; no anteroventral spine or bristle at base of first joint of front tarsi; subcostal vein (= vein R 1) not dilated towards tip”. Except for the last character of couplet (14), in which R 1 vein is slightly wider at apex, E. angustipennis fits Empis group II. Further in the key it runs to couplet 18 of E. polita Macquart, 1838 through: (16) “thorax with three dark stripes”; (16b) “face bare” and (18) “only hind tibiae at base (♂), or much more extensively (♀) yellowish”. When compared to the re-description of E. polita ( Rafael 2001) , E. angustipennis differs by: incomplete stripes on scutum (complete in E. polita ), fore tarsomere 1 slightly wider than tibia (thinner than tibia in E. polita ) and female terminalia entirely different (compare Rafael (2001, figs 15, 16) with Fig. 9). Since the leg coloration does not exactly fit the couplet’s characters, one would proceed to couplet (20) “legs black”; (21) “anal vein (= vein A 1) abbreviated” and then reach E. retroversa Collin, 1933 . However E. angustipennis has a complete A 1 vein. Based on the characters presented here, E. angustipennis is not conspecific with the two species discussed here.