27 mm body length (guide photo)
Body Length: (30-35 mm)
Body Length (~1.0-1.25 inches - max 1.4)
Total length incl. wings (~2.0 to 2.25 inches)
Based on reports, Canadian examples seem a bit smaller by comparison to those specimens collected in the US (appears closer to canicularis in size)
(Larger sample sizes collected from across the range are needed to more accurately address these observations)
Similar to linnei and pruinosus
Physical traits based on specimens collected in the US (some collected while singing or responding to calls - positive id's).
1) complete black face mask
2) ventral black abdominal stripe (often better delineated than in linnei or canicularis & much better developed than seen in pruinosus/winnemanna)
3) Usu. no bow to costae (Rare examples may exist)
4) males have short oblique reddish-tan opercula (may be olive greenish-tan opercula in quasi-teneral males)
5) females usu. possess paired white spots at the base of the abdomen (> seen in fem. of linnei but < seen in fem. of pruinosus)
6) there is usu. a thin black hair-line mark that bisects the pronotal collar vertically (not observed in winnemanna or pruinosus populations across the southeast / rare in linnei / may be present in some northern pruinosus - observed in some suspected hybrids)
The call of robinsonianus across the Southeast & lower Mid-West is best described as follows:
First stage involves an "electrical sounding" buzz gradually increasing to a constant low pitched buzz (as in pruinosus) followed by intermittent pulses (....Zzzzape........Zzzzape........Zzzzzape). The buzz is best heard when close; however, the "ratchety Zzzzape" carries and often is the only component of the call heard. These "Zzzzzape" pulses usually seem quite spaced out, but at times may be more sequential (Zzzzape-Zzzzzape-Zzzzape-Zzzzape.....). The call of this cicada seems to carry over a much greater distance than does the call of related taxa like linnei, canicularis or even pruinosus. Observations & limited audal analysis suggest the call of this cicada is not truly intermediate to that of "linnei & canicularis", both of which are better described as rapid. However, it is perhaps more similar to that of a much slower augmented pruinosus (?). (per. comm. & per. observ.)
Widespread across the Southeast (Mid-South & Upper South)
Scattered reports from the Mid-West
Scattered reports from s. Canada
NOTE: Canadian examples do not seem consistent in habitat preference (plant communities) or morphological characters seen in populations or specimens collected from the Southeastern and lower Mid-Western US.
Dr. Hamilton reports Canadian examples of "robinsonianus" appear to be hybrids between T. canicularis and T. linnei; however, populations represented across the US far to the south seem distinct. It is not unlikely that T. linnei and T. canicularis hybridize to the north and these hybrids may possess overlapping characters with T. robinsonianus to the south (?) - as several Tibicen species possess overlapping traits often confounding id.
NOTE: To date, the consensus is that T. robinsonianus (as originally described) is a distinct taxon with a southern and central US distribution and not of hybrid origin (per. comm.).
Sanborn reports n. FL (?)
No additional info on Florida records is available (per. comm.)
Common in the higher grounds = "Hill Country"
(incl. the Fall-line hills, Cumberland Plateau, Piedmont Plateau, upper and mid-Mississippi River Valley, and scattered across Appalachia - possibly occurs in the lower elevations on the fringes of the upper Coastal Plain)
Widspread and most common in the following states:
n. LA, AR, OK, MO, KY, TN, MS, AL, GA, SC, NC, & VA
Also found in parts of the lower Midwest incl. the south & central parts of IL, IN and OH
Reported from e. TX(?), WV(?) and MD(?) ... likley found in a few northern states immediately adj. to VA
NOT verified to occur in the northeastern US, upper mid-Atlantic & New England, or the Great Lakes region of the US (per. comm.).
Cicadas with "similar morphologies" have been collected and reported far to the north (New England & Great Lakes), but these specimens seem most congruent with T. canicularis and suspected to belong to that taxon. Audal records for T. robinsonianus have not been verified north of the Mid-Atlantic (Chesapeake Bay region) in the eastern US nor has it been confirmed from the upper mid-West/Great Lakes region of the US (per. comm. & reports), ... thus suggesting, specimens identified as robinsonianus from these areas likely belong to related taxa (i.e. canicularis).
This cicada is most abundant in highland areas where limestone outcroppings and "cedars", Juniperus spp. and related trees are abundant. These cicadas are also often heard along rivers where limestone and "cedars" are prevalent (n. Alabama & c. Tennessee).
Scattered reports across the lower Southeast place them in mixed pine & hardwood forests, but even in these vegetative communities, junipers seem to always be nearby.
These cicadas may accept hosts other than junipers ("cedars"), but do seem to be most associated with related conifers.
The life cycle of this species across the US range seems to revolve around plants in the Cupressaceae (junipers - a.k.a. "cedars" & Cypress spp.).
In captivity, and when given a choice, adults also seem to prefer plants in this Family as well.
Here in NC (and reported elsewhere), T. robinsonianus nymphs, casts and adults frequent "leyland cypress" in both suburban yards and urban landscapes.
Hosts preferred by T. robinsonianus include:
Juniperus spp., "Cedars"
Cupressus spp., Cypress
Cupressocyparis spp., Leyland Cypress
Various related "juniperus" cultivars & ornamentals used in landscapes (per. observations)
Similar to linnei, pruinosus, winnemanna, and canicularis
Side Notes (per. observ. & per. comm. / based on series of collected specimens):
Robinson's Annual Cicada shares some interesting behavioral & morphological traits with Tibicen latifasciatus (Davis 1915) [syn. T. pruinosa latifaciata], "Coastal Scissor(s) Grinder Cicada"
(per. observ. + commentary in Davis' papers)
1) Like latifasciatus, robinsonianus seems to also be a cedar specialist, showing a preference for members of the Cupressaceae, esp. Eastern Red Cedar (Juniperus virginiana
). Here in the southeastern US & across much of the US range, the distribution of this cicada closely parallels that of Eastern Red Cedar (collection reports suggest this cicada is increasingly rare to absent along the northern limits of the red cedar range).
2) Both species tend to call most actively during the day between mid/late-morning and late afternoon/early evening.
3) The clypeus ("clypeal shield/pump") in both species "tends to project forward" a bit more than seen in other members of this complex (perhaps this trait is an artifact of host affinities - Juniperus spp. ... ??)
4) Both taxa usually possess evidence of a bisected pronotal collar.
5) The dorsal color and pattern are strikingly similar (minus the white abdominal stripes of latifasciatus).
6) Both taxa possess a well delineated ventral black stripe and are very similar ventrally
7) The males of both taxa posses short oblique tan to brown opercula.
There has been some speculation that T. robinsonianus may be a hybrid between linnei and canicularis, however, given the geographic ranges of the three, this hypothesis seems unlikely across much of the robinsonianus range.
Despite the original description comparing this cicada to T. linnei, there is some thought, T. robinsonianus may actually be more closely allied to the "pruinosus complex" than to any other members of the "Green Tibicen" group (molecular studies may yield different relationships among these insects?).
(per. comm. & per. observ.)
"Green Tibicen Species"
Collectively, yet informally, referred to as the "Green Tibicen species" (per. comm.), the following cicadas are often difficult to differentiate and all appear to be very closely related. Genitalic analysis of the males suggest these species are very closely related and morphological differences between and among the species are slight. It is also thought (based on observations) that several of these may be involved in complex hybrid zones; however, more work is needed to substantiate and better understand these observations.
Tibicen pruinosus pruinosus var. fulvus Beamer 1924 [syn. T. pruinosa var. fulva], "Pale Scissor(s) Grinder Cicada"
"Southern Dog-day Cicadas"
Loosely & informally referred to as the "Southern Dog-day Cicadas" (suggested - Reynolds 2010), the following taxa are mostly "southern" in distribution and appear to be closely related. These cicadas share several traits, incl. elongated opercula in the males, rapid trill and/or clicking calls, and unusually wide heads relative to body dimension (head widths usu. exceed thoracic widths).
(*appears to be the most divergent member within this group - ??)
Davis, 1922. An annotated list of the cicadas of Virginia with description of a new species. Journal of the New York Entomological Society 30: 36-52. (original description--available on Google Books