Holopogon

Like Cerotainia, these are also tiny twig-perchers, but they have shorter antennae. There are two species of Holopogon verified from Florida which can be distinguished by the wing color, color of the abdominal segments, and hair color. H. gullutus and vockerothi have clear (hyaline) wings, and H. phaeonotus has brown wings. If there is considerable gray on the sides of the abdomen, then it’s H. guttulus, but H. phaeonotus and many H. guttulus specimens have primarily black abdomens. Identification of other species of Holopogon relies of tibia and femora shape, relative leg bristle length, wing color, and the color of the stripes on the thorax. Characters summarized below were provided to me by Michael Thomas (who has a 180-specimen series of H. phaeonotus in his collection), Back (1909), and Martin (1959).

(Page under revision)

Holopogon guttulus

Wings clear. Gray coloration on first or more lateral tergites (abdominal segments). Hairs on ocular tubercle black, and white hairs on the occiput (behind the eyes). Katatergal setae white.

Abdominal tergite 1 (closest to the thorax) has dense gray hairs on the sides, and abdominal segments 2-4 are mostly gray (female) or brown (male) on the sides. However, this is a highly variable species.

Size: 8 mm

Range: Eastern U.S. south of NJ

FL Season: April-May

FL Range: Throughout south to Highlands County

Holopogon phaeonotus

The wings are light brown, longer, and more narrow than other eastern species. Hairs on top of head, including ocellar and occipital setae, are black. The katatergal setae are straw-yellow. The color difference in the katatergal setae is discernible under a scope though may be difficult to see in photos. Hind tibiae are club-shaped with a diameter greater than the hind femora.

The side of the first abdominal segment may have dense brown hairs, but the abdomen is mostly shining black. Abdominal tergite 1 (closest to the thorax) has hairs on the sides that are either thin or dense brown. Abdominal segment 2-3 and sometimes 4 may be narrowly brown, but abdominal segments 3-4 are usually entirely shining black. However, this is a highly variable species.

Size: 8 mm

Range: Eastern U.S. and Canada

FL Season: Late March-May

FL Range: South to Orlando

Holopogon vockerothi

This species has been recorded from Mitchell County in southern Georgia (Martin, 1959), and there are specimens from Archbold Biological Station in Highlands County, but I have not verified these. It is very similar to H. phaeonotus, but the wings are clear and broader. White ocellar setae, black hairs on the occiput, katatergal setae white.

H. phaeonotus and H. oriens have a median brown stripe on the thorax bordered by paler stripes. In H. vockerothi, the median brown stripe on the thorax is bordered by black stripes.

Size: 7 mm

Range: Eastern U.S. and Canada

FL Season: April

These photos by Mike Reese may be H. vockerothi.

Holopogon oriens

This species has been recorded in Georgia. It is very similar to H. phaeonotus, but the tibias are relatively uniform in width as opposed to being club-shaped as in H. phaeonotus. The tibias are similar in diameter to the hind femora. Wings clear (hyaline), short, and broad. Ocellar setae black. No pollinoise patterns on dorsum of abdomen.

Size: 6 mm

Range: Eastern U.S.

References:

Back, E. A. (1909). The robber-flies of America, north of Mexico, belonging to the subfamilies Leptogastrinae and Dasypogoninae. Transactions of the American Entomological Society (1890-), 35(2/3), 137-400.

Martin, C. H. (1959). The Holopogon complex of North America, excluding Mexico, with the descriptions of a new genus and a new subgenus (Diptera, Asilidae). American Museum novitates; no. 1980.