Rhopalosyrphus (s.s.) robustus Reemer

Reemer, Menno & Stahls, Gunilla, 2013, Generic revision and species classification of the Microdontinae (Diptera, Syrphidae), ZooKeys 288, pp. 1-213 : 115-117

Rhopalosyrphus (s.s.) robustus Reemer sp. n. Figs 337-341

Type specimens.

HOLOTYPE. Adult female. FRENCH GUYANA. Label 1: "FRENCH GUYANA. Patawa, / 4°32.658"N-52°9.132"W / VIII.2008. Malaise trap in / pine forest. Leg. O. Morvan"; label 2: "J. Skevington / mol. specimen no / JS3616 - CNC coll."; label 3: "Voucher code M. Reemer / 271 / DNA voucher labcode MZH:Y1066". Coll. CNC.

Diagnosis.

Care should be taken in assessing the presence of pile on the katepimeron: in this species this pilosity is very sparse and limited to the anterior margin. Within Rhopalosyrphus s.s. this species is readily distinguished by the pair of large yellow maculae on tergite 2.

Description (based on holotype).

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.

Etymology.

The Latin adjective robustus (strong as oak - Robur) was chosen as the specific epithet because of the size, robustness and stout hind femora of this species, which evoke the impression of a stout fly (strong animal).