One of the most distinctive traits of Scleropogon is the very narrow head, as high as wide. In Florida, only two species share this trait: Scleropogon floridensis and Scleropogon subulatus.
In Texas and Oklahoma, there are also Stenopogon, Ospriocerus, and other species of Scleropogon that have this trait.
The primary difference between the two species are that Scleropogon floridensis has hind femora entirely black, and S. subulatus has reddish hind femora, at least distally.
I suspect the two species are clinal, and S. floridensis may not be valid.
According to Wilcox (1971), S. floridensis should have several other distinguishing features. However, individuals identified as S. floridensis on Bugguide and iNaturalist do not exhibit all of these traits. Wilcox (1971) also noted:
“One male from Gainesville, Florida, 21 July 1957 (Bill Platt), FSCA, has the mystax black with the oral bristles golden, and the upper occipitals black. Otherwise the characters agree with S. subulatus but it indicates that it might merge with S. floridensis which so far has only been found farther south in Florida.“
|S. floridensis||S. subulatus|
|Mesonotum (dorsum of thorax)||black||reddish with black stripes|
|Hind femora||black||reddish, at least distally|
|Fore femora||apical fourth reddish||reddish with dorsal black stripe on basal 2/3|
|Abdomen||black||reddish or yellowish|
|Abdominal segments (tergites)||Tergite 2 and all of 3-5 reddish||Tergites 6-8 and genitals brownish|
|Male mystax||upper half black||reddish to yellowish|
|Female mystax||all yellowish||golden|
|Antennae||black||antennal segments 1-2 yellowish|
|Male genitalia||Small||Larger according to illustrations|
|Length||18-25 mm||20-28 mm|
Length: 18-25 mm
Range: Recorded from Orange County, Polk County, Hillsborough County, and Miami-Dade County. Scleropogon floridensis is a Florida endemic.
Note that the male below is lacking the black thorax (though it is fairly black on the specimen treated with acetone) and does not have a black mystax (face beard). It is 25 mm. The female below is 22 mm.
Length: 20-28 mm
Range: North Carolina south to Florida and west to Kansas and Texas.
FL Range: North Florida south to Marion County.
Season: June through August.
Wilcox (1971) notes the following:
The color of the abdomen of the coastal specimens tends to be yellow and the wings dark brown; inland specimens have the abdomen yellowish brown and the wings lighter brown; however, there are exceptions in each area.
The first two photos below are males, and the third is a female. On the males, note the orange thorax, orange abdomens, and orange genitalia. The hind femora are also only partially black.
The following three individuals are somewhat intermediate based on the extent of black on the abdomen, on the hind femora, and color of the thorax. I’m unsure where to place these.
Male in Levy County, FL by Rick Owen
Female in Talbot County, GA by Giff Beaton