Specimen Info

Dorsal view of two specimens of Monoceromyia pulchra from the collection of the California Academy of Sciences.

[Note: The species would be referred to as Ceriana (Monoceromyia) pulchra by those who follow the 'subgenera scheme' for nomenclature of subtaxa within the tribe Cerioidini. For more on this issue, see the last 5 paragraphs of my comment below this iNat post.]

Specimen at left collected from Oumé, Côte d'Ivoire (Ivory Coast) on Jan. 20, 1991 by W. J. Pulawski.

Specimen at right collected 15 miles southwest of Windhoek, Namibia at 1800 m elevation on Dec. 29, 1966 by E. S. Ross & K. Lorenzen.

The curated museum identifications for both specimens were made by A. E. Whittington, who has authored a number of papers on Afrotropical Syrphidae.

From contiguous eyes at top of head, both specimens are males. And (assuming they're correctly determined to species) together they exhibit noticeable intraspecies variation in terms of color, size, shape of abdomen, and the absence (resp. presence) of posterior yellow bands on tergites II and beyond.

Identification Notes & Reference Links

From the length of frontal prominence here (i.e. longer than the first true antennal segment) and the very narrowed & elongate 2nd abdominal segments...both these specimens would clearly be placed in the contemporary group Monoceromyia, with older synonymous genus names including Ceria and Cerioides.

The original description of Cerioides pulchra was written in 1913 by Hérve-Bazin based on two female specimens. His key to (the then known) species is here. The specimen on the left goes unambiguously to pulchra in that key, but not the specimen on the right (due to the presence of yellow posterior borders on the abdominal segments, it would go to afra).

Both specimens go to Cerioides pulchra using the (very limited) key in Bezzi(1915), though he states that pulchra is ''very closely allied to hopei, Saund., but distinguished by having the lateral stripes on the thorax dark reddish and less distinct, instead of broad and yellow''. Bezzi's 'lateral stripes on the thorax' presumably refers to those connecting the humeri to the suture (anterior to the wing bases)...which are yellow in the specimens here. The discrepancy could be due to intraspecies variation. Bezzi indicated he examined just one female specimen of pulchra, which presumably had those stripes reddish, and from that he may have presumed this was a consistent character of pulchra. But while Hérve-Bazin's original description (in French) initially indicates the borders of the (dorsum) of the thorax were reddish, he also states the humeral callus was yellow...with that yellow sometimes extending as a band to the suture (italic emphasis mine...see Hérve-Bazin's 2nd & 3rd sentences in the 2nd paragraph on pg. 82 here).

Using the key in Curran(1938) this goes to either Cerioides pulchra or perhaps C. gambiana or C. hopei due to ambiguity at couplet 9 in the key. Saunders 1845 descriptions of gambiana and hopei appear here and here, and are dipicted in his Figures 4 and 6 here.

Personally, I'm well-persuaded the specimen of the left (from Ivory Coast) fits well under pulchra...but less so for the specimen on the right (from Windhoek), due to its paler ferruginous & yellow-banded abdomen and the two narrow brown medial stripes on its face connecting connecting the antennal bases to the top of the oral margin (see this photo). Those characters suggust Ceriodes gambiana per Curran's 1938 key...and Hérve-Bazin's original description of pulchra seems to make clear that the abdomen from the posterior of the 2nd segment and beyond is uniformly dark...as in the Ivory Coast specimen on the left here. For a putative post of Monoceromyia gambiana, see here.

This species is listed as Ceriana (Monoceromyia) pulchra on pg. 95 of the 2010 Afrotropical Syrphidae catalog (unpublished manuscript) by Dirickx, De Meyer, Ssymank, and Thompson. The species entry there cites a 2004 reference by Whittington on Afrotropical Syrphidae. Note that neither of the localities here (i.e. Côte d'Ivoire & Namibia) are within the range indicated in the catalog, which was given as ''Zaire, Nigeria, Zimbabwe, and Zambia''. (And the ranges of M. gambiana and M. hopei are given as ''Gambia'' and ''Sierra Leone'', respectively...so the situation for the 2nd specimen is not clarified by currently recorded species ranges.)