This bug was attracted to a blacklight. Both flavicollis and viridis are reported from south Florida (1). After reading Eger's 1978 revision of the genus and comparing the present images with those of my one viridis from south Texas, I've concluded that this bug is flavicollis. I will add some notes to this observation below.

While acknowledging that examination of genitalia may be required for solid species determination, that has never detered me from examining living images to tease apart similar species where possible. From a careful view of available images on BG and my single records from FL and TX, I can see the following slight differences between my putative flavicollis and viridis. It is unknown which, if any, of these differences will hold up upon examination of further images or specimens. I invite critical review:

— The humeral spines in flavicollis are directed laterally and perpendicular to the body axis; the rear margin of the spines is slightly convex.
— The humeral spines in my one viridis specimen appear to be directed slightly forward of perpendicular, with the rear margin of the spines straight.

— The forward outer margins of the pronotum of both species (in front of the humeral spines) is finely “crenate” or dentate, but in flavicollis this dentition seems to decrease in size as one approaches the humeral spine to the extent that the front edge of the humeral spine is smooth.
— In viridis, the dentition on the front edge of the pronotum is realtively uniform at least to the base of the humeral spines; the spines may have 2 or 3 small dentitions on its forward base. [CWS note: On further examination, I'm not sure this distinction holds.]

— The overall color of the upperparts in flavicollis is typically almost uniform dark green (see below).
— Viridis appears finely mottled with roughly equal parts dark and light green. Both species have widely scattered lighter green dots on the coria.

— The surface of the pronotum and scutellum of both species is minutely rugose. In flavicollis, the dark green overall coloration is coupled with just limited paler dots on the raised surfaces of the bumps.
— In viridis, all of the raised/higher surfaces of the rugose areas are lighter green and the dark green is mainly confined to the low areas or pits within the surface.

— The humeral spines and forward lateral margins of flavicollis are strongly tinged with red. The spines are red with a yellowish foreward basal edge. This red stripe, just inside the yellowish-green dentate margin, narrows towards the front of the pronotum.
— In viridis, on the single individual I photographed, the humeral spines are yellow and there is no red margin forward of them.