Neohybos, Ale-Rocha, R. & De Carvalho, C. J. B., 2003

Ale-Rocha, R. & De Carvalho, C. J. B., 2003, Neohybos gen. nov. (Diptera, Empidoidea, Hybotinae) from the Neotropical Region, Zootaxa 387, pp. 1-16 : 3-5

Neohybos gen . nov.

Hybos Meigen, 1803:269 (part).

Euhybus Coquillett, 1895:437 (part).

Type­species. Hybos luridus Bezzi, 1909 , by the present designation.

Etymology. neo (Greek): new + Hybos = New Hybos . Gender masculine.

Diagnosis. Distinguished from other genera of the Hybotinae by the narrowly dichoptic eyes on face; flagellum ovate, arista bare, apical; proboscis short; labellum membranous bearing pseudotracheae; scutum with reduced number of bristles, dc and acr arranged in discrete series on prescutellar disc; wing narrow, elongated, costal cell and anal lobe narrow; Rs short; cell cup longer than cell bm; male terminalia asymmetrical; male eighth abdominal segment not rotated to right, hypandrial arms forming narrow, sclerotized dorsal bridge around phallus; Tg8 of female with a single sclerotized plate.

Description. Body length 3.5–5.5 mm.

Head. Frons holoptic. Eyes narrowly dichoptic on face, upper ommatidia enlarged.

Antenna placed at middle or slightly below head's middle; flagellum small, oval; arista bare, apical. Proboscis short; labellum membranous with pseudotracheae and short sensorial bristles. Ocellar triangle not protuberant with 1 ocellar pair of bristles. Post­cranium pruinose, convex; post­ocular series discontinuous, upper bristles bent forwards; occipital setae variable, frequently numerous.

Thorax. Scutum usually pruinose, rarely shiny, with scattered bristles, anterior ones reclinate and posterior ones, on prescutellar disc, proclinate; dc row uniserial and acr row uniserial to biserial, arranged in discrete rows on the prescutellar disc; ial numerous. Outstanding setae: 2 npl; 1 pal; 1 or more sctl. Propleural bristle present.

Wing narrow, elongate, hyaline or slightly brown tinged. Rs short. R4+5 and M1 parallel or convergent. Cell cup longer than bm, convex apically. Costal cell and anal lobe narrow, alular incision straight to obtuse. Vein CuA2 faint, long and sinuous close of wing margin.

Legs with following outstanding bristles: fore and mid tarsomere 1 with 1A and 1P preapical, mid tibia with several apical AD and 1AV bristles, first fore and mid tarsomere with 3 preapical bristles (1D, 1A and 1P) and 1D in middle, first mid tarsomere with 1 subbasal PV; hind femur with series of AD and A bristles and spine­like AV, V and PV bristles.

Abdomen shiny, with pruinescence confined to Tg1 and Tg8; lateral of Tg1­Tg3 with long bristles. Tergite 8 short, entirely sclerotized; male eighth abdominal segment not rotated 45º to right.

Male terminalia pruinose, asymmetrical. Epandrium divided dorsally, surstyli not articulated. Bacilliform sclerite strongly sclerotized, connected with hypandrial bridge dorsally. Subepandrial sclerite usually projected beyond posterodorsal margin of left epandrial lamella. Hypandrium prolonged distally with apically developed hypandrial lobe; hypandrial arms narrowed and sclerotized forming ring (dorsal bridge) around phallus. Postgonites united ventrally forming continuous structure, belt­like, around base of phallus ventrolaterally. Phallus robust. Dorsal and ventral ejaculatory apodemes developed and sclerotized. Female terminalia with sclerites modified starting from segment 7, with protuberances, reentrances, thorns or elongate spine­like setae; Tg 8 with single sclerotized plate; St 8 usually divided basally.

Distribution. Neotropical with records from the Antilles, Central America and northern South America.

Included species. The genus currently includes: Neohybos hallexus (Smith) , comb. nov.; Neohybos halteralis (Bezzi) , comb. nov.; Neohybos luridus (Bezzi) , comb. nov.; Neohybos leptogaster (Melander) , comb. nov.; Neohybos derodactylus (Melander) , comb. nov. and several undescribed species.

Remarks. Adults of Neohybos are distinguished from Euhybus Coquillett and Cerathybos Bezzi by the combination of following characters: face dichoptic and usually short; anal lobe narrowed; alular incision obtuse; scutum with reduced number of bristles, dc and acr arranged in discrete series on prescutellar disc; narrow hypandrial arms forming a sclerotized ring around the phallus and the hypandrium with the medium portion wider than or at least as wide as the base; male eighth abdominal segment not rotated; Tg 8 of female with single sclerotized plate. Neohybos stands out from other genera of Hybotinae by the characters above, plus the apical and bare arista, proboscis short with a membra­

nous labellum bearing pseudotracheae, vein Rs short, veins R4+5 and M1 parallel or slightly convergent, cell cup longer than cell bm and male terminalia asymmetrical.

The male terminalia of Neohybos are derived in several aspects in relation to the ground plan of the subfamily and provide its main diagnostic characters, of great taxonomic and phylogenetic importance. In the ground­plan of Hybotinae , the epandrium is deeply emarginate, with the epandrial lamellae united dorsally by a narrow bridge; distal margin of hypandrium with a pair of posterior lobes; surstyli not articulated; postgonites long, articulated with the hypandrial arms; ventral apodeme long, uniting the postgonites ventrally. These characters are distributed throughout related subfamilies; e.g. Bicellaria Macquart ( Sinclair 1996, Figs. 26–29 ) and Oedalea ( Chvála 1983, Figs. 318–320, 341– 347). In Neohybos , the epandrial lamellae are separated dorsally; hypandrium is prolonged distally with a developed apical hypandrial lobe usually on the right side, the left hypandrial lobe reduced or lacking; the phallus is robust, tubular, with two ejaculatory apodemes dilated apically, articulated at the base of the phallus, the right apodeme sloping, almost horizontal and the left one vertically positioned; the postgonites, positioned at the base of the phallus, are short and united ventrally forming a single ventrolateral structure, belt­like around the base of the phallus. However, the surstyli are not articulate, the bacilliform sclerite is still strongly sclerotized and articulated with the hypandrial bridge dorsally as in the Atelestinae and in the most basal genera of the Hybotinae and in the primitive genera of the Ocydromiinae ( Chvála 1983, Figs. 311, 312; Cumming et al. 1995, Figs. 10 a, b, c; 12a, b).

Phylogenetic relationships. The genus belongs to the Neotropical group of hybotine genera with a short membranous proboscis bearing pseudotracheae. Neohybos is the sistergroup of the lineage formed by Euhybus Coquillett and Cerathybos Bezzi , the most derived monophyletic group within the subfamily Hybotinae . These three genera share the reduced or absent ventral apodeme of the postgonites; furca and epifurca (Kristoph 1961) thin and longitudinal, and pseudotracheae present.

The pseudotracheae are present in the most basal genera of Hybotinae ( Chillcottomyia , Lamachella , Stenoproctus , Acarterus and Afrohybos ) and they were lost in the group with proboscis strongly sclerotized ( Syneches , Hybos , Syndyas , Lactistomyia and Smithybos ). The presence of pseudotracheae in the group formed by Euhybus , Cerathybos and Neohybos is considered a reversal. The furcal plates are plesiomorphycally wide in the most genera of the Hybotinae .

Euhybus and Cerathybos share holoptic eyes in the face, separate postgonites, membranous hypandrial arms, male eighth abdominal segment rotated, bacilliform sclerite parcially incomplete, and tergite 8 of female with three plates. However, in Neohybos those structures still keep the primitive state found in basal genera of Hybotinae : face dichoptic and usually short; postgonites united ventrally; hypandrial arms narrow; male eighth abdominal segment not rotated, bacilliform sclerite directly articulated with the hypandrium (just the right in Neohybos ) and tergite 8 of the female formed by a single plate.

Figures

FIGURES 26 – 30. Neohybos species, wings: 26, N. derodactylus comb. nov.; 27, N. hallexus comb. nov.; 28, N. halteralis comb. nov.; 29, N. leptogaster comb. nov.; 30, N. luridus comb. nov.

FIGURES 8 – 15. Neohybos species, terminalia. N. hallexus comb. nov., paratype female: 8, 9, 10, ovipositor, dorsal, ventral and right lateral view. Figs 11 – 5. N. leptogaster comb. nov., lectotype male: 11, epandrium, ventral view; 12, epandrium and cerci, dorsal view; 13, 14, epandrium, left and right lateral view; 15, hypandrium, ventral view. Figs 8 – 10; 11 – 14; in the same scale (scale bar = 0.5 mm); 15 (scale bar = 0.5 mm).