The single species of Notosyrphus is almost certainly related to Dasysyrphus but differs from that genus in the parallel-sided face, in the more extensive katepisternal pilosity, in the reduction of wing microtrichia, in the much larger non-lunulate abdominal markings and in many features of the genitalia. Among the latter are the elongate and slender surstylus, superior lobe and lingula, and the very different configuration of the aedeagus. The skatepisternal pilosity of Notosyrphus is very similar to that of Scaeva. The reduction of the wing microtrichia also suggests a relationship with Scaeva, although it has not extended nearly as far as in that genus. The enlarged dorsal eye facets of the males of Scaeva also serve to distinguish the two genera, as do many differences in the genitalia (from Vockeroth 1969).
Adapted from Vockeroth (1969).
Moderately large robust species with three pairs of large rounded oblique yellow maculae on abdomen.
Head: Eye pilose. Face parallel-sided, yellow, densely pollinose, with moderately distinct dark brown medial vitta. Thorax: Scutum black, subshining, with broad faint submedian grey-pollinose vittae on anterior 2/3, notopleuron weakly pollinose, postsutural margin sometimes obscurely yellowish. Scutellum yellow-brown. Pleura black, shining, with obscurely pollinose areas on anepisternum and katepisternum. Dorsal and ventral katepisternal pile patches narrowly joined posteriorly; anterodorsal corner of katepisternum with tuft of hairs which is scarcely separated from an anterodorsal extension of the ventral patch. Metasternum bare. Wing membrane with extensive bare areas on rather more than basal half-second costal cell with only a few scattered microtrichia, cell R4+5 entirely bare behind spurious vein, alula with large bare area on anterior half; apical fifth of wing with dense and uniform microtrichia. Abdomen oval, moderately broad, with distinct margin from near middle of tergum 2 to end of tergum 5. Terga 2 to 4 each with a pair of large, rounded, oblique, non-Iunulate yellow maculae none of which extend to the lateral margins. Sterna yellow or with obscure dark median maculae or triangles.
Male genitalia: Surstylus extremely long, slender, curved slightly ventrad, with a slight dorsomedian swelling on basal half. Sternite 9 deepened, much longer ventrally than dorsally, with shallow anteriorly broadened posteroventral emargination and moderately long slender curved lingula which extends caudad beyond base of superior lobe. Superior lobe elongate, directed caudad, compressed, broad basally and tapering to rounded apex, with dense fine pile on most of inner surface. Aedeagal base short, elongate dorsoventrally, posterior and dorsal surfaces rounded, ventral half slightly compressed and apically with broad depressed tapering subacute anteroventrally directed process. Distal portion of aedeagus tubular, very slightly enlarged towards apex, distinctly sclerotized only posteriorly, with preapical posterior notch; apex slightly depressed, with weak lateral flange, and with a few scarcely discernible spicules anteriorly.
Body length: 10.4 to 11.5 mm (Vockeroth 1969).
Notosyrphus golbachi is known from Argentina and Brazil.