Genus Xenoliarus Hendrix & Bartlett 2025


[Back to North American Cixiidae]

Family Cixiidae Spinola, 1839

Subfamily Cixiinae Spinola, 1839

Tribe Pentastirini Emeljanov, 1971

Genus Xenoliarus Hendrix & Bartlett 2025

Type species Oliarus placitus Van Duzee, 1912.

Distribution

Transcontinental U.S. and southern Canada (most abundant in eastern U.S.); Belize.

Recognized species

Xenoliarus eximus (Caldwell, 1947): USA (CA, NM).
Xenoliarus montanus (Metcalf, 1923): USA (DE, GA, IL, KS, MD, MO, NC, NJ, NY, OH, PA, TN, VA).
Xenoliarus placitus (Van Duzee, 1912): Canada (ON); USA (AL, AR, DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, MI, MO, MS, NC, NE, NJ, NY, OH, OK, PA, SC, SD, TN, TX, VA).
Xenoliarus teximus (Caldwell, 1947): USA (TX).

Economic Importance

Not reported as pests.

Plant associations

X. montanus – Malus sp. (Rosaceae), Carya sp. (Juglandaceae) (Mead & Kramer 1982).
X. placitus – Citrus sp. (Rutaceae), Malus sp. (Rosaceae), Cornus foemina Mill. (as Cornus stricta; Cornaceae) (Mead & Kramer 1982). Acer rubrum L. (Aceraceae), Carpinus caroliniana Walter (Betulaceae), Fagus grandifolia Ehrh. (Fagaceae), Quercus sp. (Fagaceae).

Recognition

Relatively large (5–9 mm, – the eastern species X. placitus & X. montanus are larger than the western X. eximus & X. teximus), brown to black, maculae of frons conspicuous. Forewings usually clear (markings sometimes present), veins intermixed pale and dark with dark tubercles. Male terminalia with a greatly expanded, spatulate medioventral pygofer process. Gonostyli (ventral view) asymmetrical and arcuate with lobed apices. Periandrium broad bearing several large, elongate processes; ventral periandrium with singular sinistral process. Endosoma highly reduced.

Xenoliarus placitus (male); A) dorsal habitus view, B) lateral habitus view, C) frontal view, D) head and thorax, E) ventral view of cleared male terminalia.
Xenoliarus placitus (male); A) dorsal habitus view, B) lateral habitus view, C) frontal view, D) head and thorax, E) ventral view of cleared male terminalia.
Annotated left forewing of Xenoliarus placitus (male), flipped vertically. Bold/black = primary veins, bold/green = cells, italics/black = crossveins; wing nomenclature following Bourgoin et al. (2015).
Annotated left forewing of Xenoliarus placitus (male), flipped vertically. Bold/black = primary veins, bold/green = cells, italics/black = crossveins; wing nomenclature following Bourgoin et al. (2015).
Male terminalia of Xenoliarus placitus ventral view.
Male terminalia of Xenoliarus placitus ventral view.
Aedeagal complex of Xenoliarus species (ventral view); from Mead & Kramer (1982).
Aedeagal complex of Xenoliarus species (ventral view); from Mead & Kramer (1982).

Online resources

iNaturalist.
TaxonPages.

Collecting

Xenoliarus placitus is common. It comes to lights and can be found during the day by inspecting bolls of trees, especially oaks in open woodlands.

Selected references

Ball, E.D. 1934. The genus Oliarus and its allies in North America (Homoptera Fulgoriidae). Journal of the Washington Academy of Sciences, 24(6), 268–276.

Bartlett, C.R., L.B. O’Brien & S.W. Wilson. 2014. A review of the planthoppers (Hemiptera: Fulgoroidea) of the United States. Memoirs of the American Entomological Society 50: 1–287.

Caldwell, J.S. 1947. New species of Oliarus Stål from Southwestern United States and Mexico (Homoptera: Cixiidae). The Pan-Pacific Entomologist, 23(4), 145–151.

Caldwell, J.S. 1951. New Cixiidae from Southern North America with notes on others (Homoptera: Fulgoroidea). The Ohio Journal of Science, 51(1), 34–36.

Hendrix, S.V. & C.R. Bartlett. 2025. Reclassification of the planthopper genus Melanoliarus Fennah, 1945 (Hemiptera: Fulgoromorpha: Cixiidae), primarily north of Mexico, with notes on American Pentastirini. Zootaxa 5619(1), 1–87. https://doi.org/10.11646/zootaxa.5619.1.1

Hoch, H. 2005. On the identity of the type species of the planthopper genus Oliarus Stål, 1862, Oliarus walkeri (Stål, 1859) (Hemiptera: Cixiidae). Zootaxa 1056: 53–60.

Holzinger, W.E., A.F. Emeljanov & I. Kammerlander. 2002. The family Cixiidae Spinola 1839 (Hemiptera: Fulgoromorpha) – a review. Pp. 113-138. In: Holzinger, W. (ed.). Zikaden: Leafhoppers, Planthoppers, and Cicadas (Insecta: Hemiptera: Auchenorrhyncha). Denisia, Volume 4. Oberosterreichisches Landesmuseum, Linz, Austria. 556 pp.

Mead, F.W. & J.P. Kramer. 1982. Taxonomic study of the planthopper genus Oliarus in the United States (Homoptera: Fulgoroidea: Cixiidae). Transactions of the American Entomological Society 107: 381–569.

Metcalf, Z.P. 1923. A key to the Fulgoridae of Eastern North America with descriptions of new species. Journal of the Elisha Mitchell Scientific Society 38 (3), 139–230, 32 pls. https://doi.org/10.5962/bhl.part.7606

Metcalf, Z.P. 1936. General Catalogue of the Homoptera. Fascicle IV Fulgoroidea . Part 2 Cixiidae. Smith College, Northhampton, Massachusetts. 269 pp.

Van Duzee, E.P. 1912. Hemipterological gleanings. Bulletin of the Buffalo Society of Natural Sciences, 10, 477–512.

Wilson, S.W., C. Mitter, R.F. Denno & M.R. Wilson.1994. Evolutionary patterns of host plant use by delphacid planthoppers and their relatives. In: R.F. Denno and T.J. Perfect, (eds.). Planthoppers: Their Ecology and Management. Chapman and Hall, New York. Pp. 7–45 & Appendix.

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