Rhopalosyrphus

Rhopalosyrphus is a genus of hoverflies, with nine known species. The adults flies mimic wasps, such as Zethus. The larvae are predators of ant brood. They are native to from southern United States to northern Argentina.

Rhopalosyrphus es un género con nueve especies conocidas de insectos dípteros pertenecientes a la subfamilia Microdontinae (familia Syrphidae o moscas de las flores).​ Antes recibía el nombre de Holmbergia.​

Los adultos imitan a las avispas tales como las del género Zethus.​​ Las larvas son detritivoras en los nidos de hormigas.

Rhopalosyrphus là một chi ruồi trong họ Syrphidae.

Body length: 9–15 mm. Slender flies with long antennae and petiolate abdomen. Head a little wider than thorax. Face more or less convexly produced on ventral half; narrower than an eye. Lateral oral margins produced. Vertex flat, entirely pilose. Occiput ventrally narrow, dorsally strongly widened. Eye bare. Eye margins in male converging at level of frons, with mutual distance 1-2 times width of antennal fossa. Antennal fossa about 1.5 times as wide as high. Antenna longer than distance between antennal fossa and anterior oral margin; basoflagellomere longer than scape, oval; bare. Postpronotum pilose. Scutellum semicircular; with or without calcars, if present, then small and with mutual distance small. Anepisternum convex or with weak sulcus; entirely pilose. Anepimeron entirely pilose. Katepimeron flat to weakly convex; with wrinkled texture; bare, partly pilose or entirely pilose. Wing: vein R4+5 with posterior appendix; vein M1 perpendicular to vein R4+5; postero-apical corner of cell r4+5 widely rounded to rectangular, with or without small appendix; crossvein r-m located between basal 1/8 to 1/4 of cell dm. Abdomen elongate, more than three times as long as wide, constricted, with narrowest point between halfway tergite 2 and transition between tergites 2 and 3. Tergites 3 and 4 fused. Sternite 1 pilose or bare. Male genitalia: phallus furcate near apex, with dorsal process long and whip-like, ventral process very short; epandrium with ventrolateral ridge.

Adult male. Body size: 9 mm. Head. Face occupying slightly less than 1/3 of head width in frontal view; black, except yellow on lateral 1/4 on dorsal 2/3; golden yellow pilose, most densely at yellow lateral parts. Gena black, yellow pilose. Lateral oral margins produced. Frons black; yellow pilose. Vertex black; yellow pilose, except black pilose posteriad of ocelli. Occiput black; yellow pilose. Eye bare; with narrow, horizontal area frontally at level of antenna with enlarged ommatidia. Antennal fossa about 1.5 times as wide as high. Antenna black; antennal ratio approximately as 5:1:8; longer than distance between antennal fossa and anterior oral margin. Thorax. Black with faint metallic hues. Mesoscutum black pilose, except narrowly white pilose along anterior margin and with small patches of white pile at notopleuron. Postpronotum and postalar callus white pilose. Scutellum semicircular; black pilose dorsally, white pilose along margins; with small apical calcars, with mutual distance about 1/5 of basal width of scutellum. Anepisternum without sulcus; entirely white pilose, except for small patch of black pile posterodorsally. Anepimeron entirely white pilose. Katepisternum white pilose dorsally, bare ventrally. Katepimeron white pilose anteriorly. Katatergum long microtrichose, anatergum short microtrichose. Calypter and halter yellowish white. Wing: Hyaline, except faintly infuscated around spur on vein R4+5, vein dm-cu, r-m and bm-cu. Microtrichose, except bare on cell bc, basal 1/2 of cell c, basally on cell r1 along vein Rs, entirely on cell br, basal 3/4 of cell bm, anterobasal 1/2 of cell cup and basomedian 1/10 of alula. Legs: Front and mid femora blackish brown, except narrowly yellow at apex; white pilose, except for sparse long, black pile posterodorsally. Front and mid tibiae pale yellow basally, dark yellow apically; white pilose, except for sparse black pile postero-apically. Front and mid tarsi yellow; black pilose dorsally, yellow pilose ventrally. Hind femur black; white pilose anteriorly and dorsally, black pilose posteriorly and with dense, bristly to spiny black pile ventrally. Hind tibia pale yellow on basal 3/5; yellow pilose, except black pilose posteriorly at apical 1/4. Hind tarsus brown; black pilose dorsally, yellow pilose ventrally. Coxae and trochanters brown to blackish; white pilose. Abdomen. Constricted, about as wide as thorax, with narrowest point just before posterior margin of tergite 2. Tergites black with bronze hues, except tergite 2 yellow along posterior margin. Tergite 1 white pilose, except white pilose on median 1/4. Tergite 2 white pilose, except black pilose dorsomedially on apical 1/2. Tergite 3 white pilose, except for dorsomedian triangle of black pile over entire length, which is widest at posterior margin; white pile posterolaterally thicker and more conspicuous, thus forming a medially interrupted fascia at posterior margin. Tergite 4 black pilose, except white pilose along lateral margins and with fascia of golden yellow pile on posterior 1/3, which is partly interrupted by black pile anteromedially. Sternite 1 dark brown; bare. Sternite 2 brown on anterior 2/3, yellow on posterior 1/3; white pilose. Sternite 3 yellow anteriorly and along posterior margin, brown medially; white pilose. Sternite 4 brown; black pilose, except white pilose along posterior margin. Male genitalia as in Fig. 352. Female. Unknown.

Adult female. Body size: 14.5 mm. Head. Face occupying about 1/4 of head width in frontal view; black, except yellow on lateral 1/6 on dorsal 2/3; entirely silvery white pilose. Gena black, white pilose. Lateral oral margins produced. Frons black; silvery white pilose. Vertex black; black pilose, except white pilose along eye margin. Occiput black; white pilose, except black pilose dorsolaterally. Eye bare; with narrow, horizontal area frontally at level of antenna where ommatidia are separated from each other by wide spaces; the ommatidia present in this area are larger than elsewhere on the eye. Antennal fossa about 1.5 times as wide as high. Antenna black; antennal ratio approximately as 5:1:9; longer than distance between antennal fossa and anterior oral margin. Thorax. Black with faint metallic hues. Mesoscutum anteriad of transverse suture appressed white pilose, except for three patches of appressed black pile, and narrowly erect white pilose along anterior margin; mesoscutum posteriad of transverse suture appressed black pilose, except erect white pilose on posterior 1/3. Postpronotum and postalar callus white pilose, except postalar callus laterally black pilose. Scutellum semicircular; white pilose dorsally, golden pilose along margins; without calcars. Anepisternum with shallow sulcus; entirely silvery white pilose. Anepimeron entirely silvery white pilose. Katepisternum silvery white pilose dorsally, bare ventrally. Katepimeron almost bare: with very sparse white pile along anterior margin. Katatergum long microtrichose, anatergum short microtrichose. Calypter and halter yellow. Wing: Hyaline, faintly infuscated on anterior 1/3. Microtrichose, except bare on cell bc, basal 1/3 of cell r1, entirely on cell br, posterobasally on cell r4+5 posteriad of vena spuria, posterior 1/2 of cell bm, anterior 1/2 of cell cup, and basomedian 3/5 of alula. Legs: Front femur brown dorsally, black ventrally; white pilose, except for sparse black pile posteriorly. Front tibia black, except brown anteriorly on basal 1/4 and apical 1/3; white pilose, except black pilose ventrally. Front tarsus black, except fifth tarsomere brown; yellow pilose. Mid femur black, except brown anteriorly on basal half; white pilose. Mid tibia black, except yellowish on basal 1/6; white pilose. Mid tarsus black on basal three tarsomeres (other tarsomeres missing in holotype); yellow pilose. Hind femur strongly swollen, about 5 times as wide as mid femur; black; white pilose, except sparsely black pilose dorsally and densely occupied with short, bristly, black pile ventrally. Front coxa and trochanter brown; white pilose. Mid coxa black; white pilose. Mid trochanter brown; white pilose. Hind coxa and trochanter black; white pilose. Abdomen. Constricted, about as wide as thorax, narrowest just before posterior margin of tergite 2. Tergites black with faint metallic hues, except tergite 2 with pair of large, elongate yellow maculae from anterior 1/4 to posterior 1/3. Tergite 1 white pilose. Tergite 2 white pilose, except for patch of black pile dorsally between middle of tergite and posterior 1/6. Tergite 3 black pilose, except narrowly white pilose along posterior and lateral margins. Tergite 4 pilose as tergite 3, but with sparse yellowish pile intermixed among the black pile on posterior 2/3. Tergite 5 mostly yellowish white pilose, with sparse black pile intermixed anteriorly, and colour of pile more whitish near posterior and lateral margins. Sternite 1 brown; white pilose. Sternite 2 yellow; white pilose. Sternite 3 brown; white pilose. Sternite 4 brown; white pilose, on anterior half, mostly black pilose on posterior half, yellowish pilose along posterior margin. Sternite 5 brown; mixed yellowish and black pilose. Male. Unknown.

Adult male. Body size: 11 mm. Head. Face occupying a little less than 1/3 of head width in frontal view; yellow, with narrow, vaguely defined brown median vitta; entirely golden yellow pilose. Gena black, white pilose. Lateral oral margins produced. Frons black; silvery white pilose. Vertex black; black pilose, except yellow pilose along anterior and lateral margins. Occiput black; black pilose dorsally, golden pilose laterally, silvery white pilose on ventral half. Eye bare; with narrow, horizontal area frontally at level of antenna where ommatidia are separated from each other by wide spaces; the ommatidia present in this area are larger than elsewhere on the eye. Antennal fossa about 1.5 times as wide as high. Antenna black; antennal ratio approximately as 4:1:9; longer than distance between antennal fossa and anterior oral margin. Thorax. Blackish brown with bronze and green metallic hues. Mesoscutum appressed black pilose, except for fasciae of appressed golden pile along anterior margin, transverse suture and posterior margin. Postpronotum and postalar callus white pilose. Scutellum semicircular; golden pilose; without calcars. Anepisternum with shallow sulcus; golden pilose anterodorsally, silvery white pilose posteriorly, widely bare anteroventrally. Anepimeron entirely silvery white pilose. Katepisternum silvery white pilose dorsally, bare ventrally. Katatergum long microtrichose, anatergum short microtrichose. Calypter and halter yellow. Wing: Hyaline. Microtrichose, except bare on cell bc, basal 5/6 of cell br, basal 1/6 of cell cup. Legs: Yellow, except hind femur dark brown and hind tibia medially dark brown. Front and mid legs white to yellow pilose, except mid femur dorsally, anteriorly and ventrally black pilose. Hind leg white to yellow pilose, except femur ventrally densely occupied with short, black, bristly pile. Front coxa orange, mid and hind coxae brown; all coxae white pilose. Front and mid trochanters yellow, hind trochanter brown; all trochanters white pilose. Abdomen. Constricted, narrower than thorax, with narrowest point halfway tergite 2. Tergites brown with faint metallic hues, except tergite 2 with pair of large rectangular yellow maculae on basal 3/5. Tergite 1 white pilose. Tergite 2 yellow pilose, except sparsely black pilose medially and white pilose along posterior margin. Tergite 3 black pilose, except white pilose anterolaterally and along lateral margin, and with fascia of golden pile along posterior margin; this fascia medially interrupted and gradually narrowing towards lateral margins. Tergite 4 black pilose, except golden pilose anterolaterally and along lateral margin, and with pair of large triangular patches of golden pile over posterior 2/3. Sternite 1 brown; bare. Sternite 2 yellow; short yellow pilose. Sternites 3 and 4 brown; white pilose. Male genitalia as in Fig. 353. Female. Unknown.

Adult male. Body size: 13 mm. Head. Face occupying a little more than 1/3 of head width in frontal view; black; entirely white pilose; ventral part of face anteriad of oral margin with lateral bulges, medially separated by shallow, smooth sulcus. Gena black, white pilose. Lateral oral margins slightly produced. Frons, vertex and occiput black; white pilose, except for sparse black pile on frons. Eye bare. Antennal fossa about as high as wide. Antenna brown; antennal ratio approximately as 4:1:3; slightly shorter than distance between antennal fossa and anterior oral margin. Thorax. Black. Mesoscutum black pilose, except for fasciae of white pile along anterior margin and transverse suture, and patches of white pile posterolaterally. Postpronotum and postalar callus white pilose. Scutellum semicircular; white pilose; with small calcars with mutual distance about equal to 1/4 of width of scutellum. Anepisternum with deep sulcus; black pilose anterodorsally, white pilose posteriorly, widely bare in between. Anepimeron entirely white pilose. Katepisternum white pilose dorsally, bare ventrally. Katatergum long microtrichose, anatergum short microtrichose. Calypter yellow. Halter brown. Wing: Hyaline, but infuscated at apical 1/2 of cell c, cell sc, around vein r-m, around vein R4+5 and posterior appendix of that vein, around vein dm-cu and around bm-cu. Microtrichose, except bare on cell bc, basal 1/2 of cell c, basal 1/2 of cell r1, basal 1/3 of cell r2+3, posterobasal 1/4 of cell r4+5, entirely bare on cell br, basal 9/10 of cell bm, basal 2/3 of cell cup, and entirely on alula. Legs: Front and mid legs orange brown, except mid femur blackish brown on basal 2/5; white pilose, except front tibia black pilose on apicodorsal 1/4, tarsi dorsally black pilose and mid femur on apical 1/2 posterodorsally with sparse bristle-like pile among long white pile. Hind leg black, except basal 1/2 of tibia and apical four tarsomeres dark brown; white pilose, except tarsus dorsally black pilose and femur on apical 1/5 with row of short, black, bristle-like pile anteroventrally; femur swollen: about 2.5 times as wide as mid femur. Front coxa brown, mid and hind coxae black; all coxae white pilose. Front and mid trochanters brown, hind trochanter black; all trochanters white pilose. Abdomen. Constricted, narrower than thorax, with narrowest point at transition between segments 2 and 3. Tergites black, except tergite 2 with pair of large elongate yellow maculae on basal 3/5 and narrowly yellow along posterior margin, and tergite 3 vaguely brownish yellow along anterior margin. Tergite 1 white pilose. Tergite 2 short black pilose, except with long white pile anterolaterally and with thick, appressed white pile along posterior margin. Tergite 3 short black pilose, except for medially interrupted fasciae of thick, appressed white pile along anterior and posterior margins. Tergite 4 yellow pilose on lateral 1/4 and posterior 3/5, black pilose anteromedially and on narrow median vitta on posterior 3/5. Sternite 1 black; bare. Sternite 2 yellow except black along posterior margin; with sparse long white pile. Sternite 3 yellow at anterior 3/5, black posteriorly; short black pilose on posterior 1/2 to 3/5, long, thick white pilose along posterior and posterolateral margins. Sternite 4 brown; black pilose medially, yellow pilose laterally. Male genitalia as in Fig. 355. Female. Unknown.

Described species: 9. Mainly Neotropical, with two species in southern parts of the U.S.A. (Arizona, Texas, Florida).