Syneches luteus (Wiedemann)

Soares, Matheus M. M., Freitas-Silva, Rafael A. P. & Ale-Rocha, Rosaly, 2021, Review of Brazilian species of Syneches Walker (Diptera, Hybotidae, Hybotinae), with description of ten new species, Zootaxa 5049 (1), pp. 1-84 : 43-45

Syneches luteus (Wiedemann)

( Figs 28A–C )

Hybos luteus Wiedemann, 1830: 647 .

Syneches luteus: Bezzi, 1909: 314 ; Smith, 1962: 213 (cit.); 1967: 10 (cat.); Yang et al., 2007: 310 (cat.). Type locality: Brazil. Diagnosis. Medium size (5.0 mm) ( Fig. 28A ). Antenna yellow, with postpedicel dark brown ( Fig. 28B ). Scutum rounded, as broad as mesopleuron in lateral view, covered with pale golden pruinescence ( Fig. 28A ). Hind femur slightly swollen; legs mostly yellow, fore tibia dark yellow, hind femur with brown spot on apex, fore and mid tarsomeres 3–5 darker ( Fig. 28A ). Wing hyaline, pterostigma inconspicuous; second section of M 1 2 x longer than crossvein r-m ( Fig. 28C ).

Re-description. Holotype ♀ ( Fig. 28A ). Body length: 5.0 mm. Wing length: 4.3 mm. Head ( Fig. 28B ). Ocellar triangle protuberant, covered with gray pruinescence; 2 pairs of ocellar bristles, anterior pair long, about 2 x longer than posterior pair. Face black covered with gray pruinescence. Antenna yellow except postpedicel dark brown; postpedicel oval, about 1.6 x longer than wide, about as long as preceding segments combined, covered with pale golden pruinescence, bearing 2 long mediodorsal bristles, about as long as postpedicel; antennal stylus brown, about 3 x longer than preceding segments combined, short pubescent, except apical 1/5 bare. Proboscis dark yellow; palpus and palpifer brown, palpus short, about 1/5 length of proboscis, covered with concolorous pruinescence, with 2 long bristles (1 apical and 1 medioventral). Postcranium black, covered with gray pruinescence. Thorax ( Fig. 28A ). Proepisternum short; prosternum isolated, not fused to proepisternum. Pronotum brown, covered with golden pruinescence. Scutum rounded, as broad as mesopleuron in lateral view, covered with pale golden pruinescence. Pleura pale brown, katepisternum and meron darker. Chaetotaxy: prescutellar disc with 1 long and thin acr bristle and 1 long and strong dc bristle; 2 npl long and strong bristle, 2 pal bristles (anterior short and thin, posterior long and strong); scutellum with 18 marginal bristles (3 bristles longer than others). Legs ( Fig. 28A ). Fore femur slightly swollen on basal half; mid femur slender; hind femur slightly swollen. Legs mostly yellow, fore tibia dark yellow, brown spot on apex of hind femur, fore and mid tarsomeres 3–5 darker. Chaetotaxy: mid tibia with 1 PV long subapical bristle, exceeding half-length of mid tarsomere 1, 1 PD bristle at mid-length, 1 AD subapical bristle and 1 AV apical bristle; hind femur with 2 AD long and strong bristles on apical third, 2 AV spiniform bristles (1 on mid-length, 1 subapical), 3 V spiniform bristles on apical third; hind tibia with 2 AD long and strong subapical bristles, 2 PD long subapical bristles reaching half-length of hind tarsomere 1, 1A apical bristle. Wing ( Fig. 28C ). Hyaline; pterostigma inconspicuous; vein R 2+3 slightly angulate near apex; second section of M 1 2 x longer than crossvein r-m; cells br and bm subequally long, both slightly longer than cell cua. Abdomen.About 2 x longer than thorax; dark brown, covered with reddish brown pruinescence; dorsal bristles shorter and brown, laterodorsal bristles longest and yellow.

Male. Unknown.

Type material examined. HOLOTYPE ♀ ( SMF) labelled: “ Brasilia [ BRAZIL], [Georg Wilhelm] Freyreiss ” . Holotype condition: body covered with fungi, thorax damaged by the pin, abdomen not dissected.

Distribution. Brazil.

Remarks. Syneches luteus is a medium size species with 18 marginal scutellar bristles. This great number of scutellar bristles and the second section of M 1 twice longer than crossvein r-m is shared with S. atratus , S. catarinae , S. curvipes and S. walkeri , which are medium to large size species. However, Syneches luteus does not have the wide prosternum nor colored pterostigma. Syneches luteus can be differentiated from the above mentioned species by the antenna yellow with dark brown postpedicel, legs mostly yellow and wing hyaline with pterostigma inconspicuous.

The extensive damage on the scutum of the holotype did not allow us to describe the acrostichal and dorsocentral series and we were not able to associate this female with any male, or even include additional specimens to this species. Wiedemann (1830) described the species based upon the specimens collected by Mr. Wilhelm Freyreiss, a German naturalist who made expeditions between 1812–1814 through the current Brazilian administrative States of Rio de Janeiro, Espírito Santo, Bahia and Minas Gerais ( Papavero 1973). Hence, despite not being able to provide a more precise distribution of the species other than that provided above, it is reasonable to suppose that S. luteus occurs in the Atlantic Forest biome and it may occur from the northern Southeast to southern Northeast Brazil.

Figures

FIGURE 28. Syneches luteus (Wiedemann, 1830). Holotype female. A. Habitus, lateral view; B. Head, lateral view; C. Wing. Figures provided by Isis Menezes.