Opacifrons DUDA, 1918

Papp, L., 2012, Five New Afrotropical Species Of Opacifrons (Diptera: Sphaeroceridae), Acta Zoologica Academiae Scientiarum Hungaricae 58 (2), pp. 121-143 : 122-123

Opacifrons DUDA, 1918

Opacifrons DUDA, 1918: 22 , as subgenus of Limosina MACQUART, 1835 .

Type species: Limosina coxata STENHAMMAR, 1855 (subsequent designation by SPULER, 1924: 121).

Gender: female.

Its Latin name means “opaque frons” and indeed, the (post)frons is not shiny. Cephalic setae: 2 pairs of fronto-orbitals; ocellars, outer and inner verticals, both outer and inner occipitals very long, postocellars very small. Some setulae present just medially and anteriorly to anterior fronto-orbital pair. No inner orbital setae. Genal seta always conspicuous. Vibrissa as long as eye. Scape rather small, its medial seta indistinct. Pedicel with very long setae. First flagellomere broader than long, with a blunt upper apex. Lunule linear, a triangle present between antennal bases. Mouth edge broadly but only moderately protruding. No bulbous emergence below inter-antennal triangle, but a moderately high ridge may be developed (e.g. in O. afrobreviscutellata ); even sagittal line is always concave.

Thoracic chaetotaxy: 1 postpronotal, 2 notopleurals, posterior one emerges on a large prealar callus (so it may be named as prealar), 1 presutural just posterior to the level of anterior notopleural (rather high on mesonotum); the posterior dorsocentral and 2 scutellar pairs rather strong; one very strong supra-alar in postalar position; in the intra-alar line a smaller intra-alar just above wing base and a postalar behind the level of posterior dorsocentral pair; a shorter dorsocentral pair emerge anterior to prealar seta. One (posterior) katepisternal seta, not even a setula in the place of anterior katepisternal. Pleura otherwise bare.

Wing not patterned. First costal section of wing with medium-long setae (only 2 to 3 times as long as costal vein diameter) but 1 long pair of sub-basal costal setae (c. 0.1 mm) always present.

Mid tibia without proximal posterodorsal seta, i.e. no paired setae on mid tibia proximally. Mid basitarsus with a sub-basal ventral seta both in males and females. No ventral apical or subapical seta on male mid tibia ventrally. Male with a partial or complete row of anteroventral, black, thick, thorn-like setae on mid tibia, a partial row of posteroventral (weaker) setae may also be present. In some species, thorn-like seta may also be present anteroventrally and posteroventrally on basal half of mid femur. Females always with subapical ventral seta on mid tibia. I do not consider the conspicuous feature of perpendicular short setulae in a distinct complete row on second hind tarsomere as well as on basitarsus as a characteristic feature (as it occurs also in numerous species); for instance, O. pseudimpudica (DEEMING) females are also with that feature. Male postabdomen and genitalia comparatively simple but very characteristic. No medial rod of hypandrium (at most a flap of membrane there), hypandrium short and strongly fused to epandrium ( Fig. 42 ). Modified cerci (cercal part of epandrial complex) with or without a pair of large cercal pegs. Subepandrial sclerite connected to the medial sclerite of the surstylus through a distinct lath (e.g. Fig. 21 ). A single pair of surstyli. Surstylus (as usual) with a lateral and a medial wall, the movement of surstylus is dependent on the muscular connections of the two walls, outer (lateral) sclerite of surstylus hamshaped (cf. ROHÁČEK 1975: fig. 5) or otherwise shaped (e.g. Figs 6, 8 ), surstylus asymmetrical in cases, and connected but not fused to the epandrium. Distiphallus short, basiphallus with a large ventral epiphallus.

Female abdomen rather short, without long setae. Sternite 7 ( Figs 47, 53 ) rather large and much longer than tergite 7, causing the anal opening to turn dorsally. Epiproct comparatively large ( Figs 50, 55 ), sagittally less melanised and sclerotised, houseroof-shaped. Cerci ( Figs 50–51, 55 ) short, not or not much longer than broad, upright with or without distinct hair-like setae but always with 2 pairs of discoloured thick thorns (in numerous cases: pegs); apices always sharp and may be lengthened in thin curved projections, cercal pegs without/with ventral incisions. Spectacles shaped sclerites comparatively large ( Fig. 52 ). Spermathecae ( ROHÁČEK 1975: figs 13–14, Figs 48, 54 , PAPP 1991: fig. 41,) globular or long, common duct of paired spermathecae rather short.

I do not think that Opacifrons is closely related to the Pseudocollinella complex. The most important paper to judge relationships is MARSHALL and SMITH’S (1993) revision of the Nearctic Pseudocollinella species. Some shared features, i.e. mid basitarsal ventral seta may be a convergent characteristic. In any case, I think the male genital structures are far more suitable to judge relationships, than features of legs. Having said that some specimens of Pseudocollinella from Africa may indeed key out to Opacifrons . The Pseudocollinella species from the Old World tropics will be discussed in a forthcoming paper.

In the male genitalia of the Opacifrons species , cercal part of the epandrial complex, the surstylus, the postgonite, basi-and distiphallus as well as subepandrial sclerite carry important differentiating characters. Here I name the sclerotised structures above the basiphallus (phallobase) and ventral to the cerci (connecting ventral arms of epandrium) as subepandrial sclerite, although its origin may be more complex. In the female postabdomen cerci and spermathecae may hold specific features (mostly not, so not all species are described in this respect in this paper).

Figures

Figs 41–46. Opacifrons subserrata sp. n., male postabdomen and genitalia. 41 = medio-caudal part of sternite 5, ventral view, 42 = surstylus with ventral edge of epandrium and lateral part of hypandrium,broadest view, 43 = sternite 5 and postabdominal sclerites (sternite 8 part slightly dislocated caudally), 44 = postgonite, broadest view, 45 = modified cerci with pegs and subepandrial sclerite (covered), caudal view, 46 = postgonite with connecting lath to hypandrium and phallapodeme, lateral

Figs 17–24. Opacifrons dilatata sp. n., male postabdomen and genitalia.17 = sternite 5, ventral view, 18 = same, medio-caudal part in higher magnification, 19 = postabdominal sclerites with contours of tergite 5, 20 = epiphallus, basiphallus and caudal end of distiphallus, 21 = surstylus, with connection to subepandrial sclerite, broadest view, 22 = postgonite, broadest view, 23 = modified cerci with holes (bases) of thin cercal pegs, caudal view, 24 = distiphallus, ventral view.Scales:0.2 mm for Figs

Figs 1–8. 1–7 = Opacifrons afrobrevisecunda sp. n., paratype male, postabdomen and genitalia. 1 = sternite 5, ventral view, 2 = same, medio-caudal part in higher magnification, 3 = postabdominal sclerites (synsternite), ventral view, 4 = subepandrial sclerite (inside) and modified cerci, caudal view (outset: cercal peg at its longest), 5 = postgonite, broadest (slightly sublateral) view, 6 = surstylus, broadest (sublateral-subventral) view, 7 = phallus, lateral view. 8 = O. brevisecunda L. PAPP, a male from Taiwan, surstylus, broadest (sublateral-subventral) view. Scales: 0.2 mm for Figs

Figs 47–55. Opacifrons spp. paratypes, female postabdomen and genitalia. 47–51 = O. compacta sp. n.: 47 = sternite 7, ventral view, 48 = spermathecae, 49 = spectacles shaped sclerite, 50 = epiproct and cerci, dorsal view, 51 = cerci, ventral view. 52–55 = O. subserrata sp. n.: 52 = spectacles shaped sclerite, 53 = sternite 7, ventral view, 54 = spermathecae, 55 = epiproct and cerci, dorsal view.Scales: