North American Cixiidae
Asotocixius diopter (Photo by Kimberley Shropshire, University of Delaware)
Worldwide Cixiidae consist of approximately 192 genera and 2,220 species (Holzinger et al. 2002, Bourgoin 2012), making them the largest family of planthoppers (only slightly larger than the Delphacidae). The higher taxonomy of Cixiidae has been examined by Emeljanov (1989, 2002), Holzinger et al. (2002), Ceotto et al. 2008, Ceotto & Bourgoin (2008), but has not yet been firmly established. The monophyly of the cixiids with respect to Delphacidae is unclear (Asche 1987, Urban & Cryan 2007, Ceotto et al. 2008, Urban et al. 2010).
Cixiidae is defined primarily by plesiomorphic features (i.e., they lack the derived features found in other planthopper families). They are the earliest derived extant family of planthoppers, originating at least 130 mya, and possibly up to 200 mya, depending on whether particular fossils are included with Cixiidae (Szwedo et al. 2004, Bourgoin & Szwedo 2008). Cixiids and kinnarids are the only families that have a median ocellus, which is located just above the frontoclypeal suture. Cixiids have a row of spines on the second hind tarsomere, and females have a well-developed ‘orthopteroid-type’ ovipositor (Asche 1988), a feature shared (in Fulgoroidea) only with Delphacidae.
Median ocellus of Oecleus sp. (left), ovipositor of Melanoliarus (right) (all photos by Kimberley Shropshire, University of Delaware)
Hind tarsus of Melanoliarus placitus (Cixiidae)
Cixiidae north of Mexico consists of 15 genera and 180 species. Kramer (1977, 1979, 1981a, b, 1983) and Mead & Kramer (1982) revised the family for the U.S., and these sources can be consulted for keys to species. Species identification relies heavily on features of male genitalia (requiring clearing of genitalia), and frequently females can not be identified beyond genus, except by association with a male. Early distribution records, before use of male genitalia was common, are questionable.
Cixiidae is diverse throughout United States, with the southwest (particularly Arizona and California) having the most species and the northwest having the fewest. Of the 15 cixiid genera found north of Mexico, 4 from the southwest are monotypic (Asotocixius, Platycixius, Stegocixius and Oliaronus). Monorachis (1 US species) is found primarily in the southeast, but also includes 2 Mexican species (Emeljanov 2001a). Nymphocixia is a Neotropical genus with 2 species, one of which is found in the southeast (on Mangrove, Rhizophora spp.). Microledrida includes 3 species in the southwest and an additional 3 in Central America. Pintalia includes 3 eastern species and an additional 22 in the Neotropics. Bothriocera has 10 species in the U.S., 8 of which are eastern, and an additional 37 species in the Neotropics. Oecleus is widespread, but nearly all the 43 U.S. species are southwestern, and 11 additional species are known in Central America.
Cixius, Myndus and Oliarus, as historically defined, are virtually worldwide in distribution, although recent workers have placed the Nearctic Myndus into Haplaxius (Holzinger et al. 2002) and Nearctic Oliarus primarily into Melanoliarus (Emeljanov 2001). Emeljanov (2001b) also moved some New World “Oliarus” into Reptalus and Pentastiridius. Additional modifications to the North American generic nomenclature appear very likely in the future, particularly since the features that purport to separate Melanoliarus and Reptalus have yet to be defined and the monophyly of Melanoliarus, Reptalus and Haplaxius needs to be established.
The distribution of Cixiidae in the U.S. (from Bartlett et al. in review)
Nymphs, and sometimes adults, are subterranean, feeding on plant roots and perhaps fungi (Wilson et al. 1994). Most nymphal host records are from grasses, whereas most adult host records are from woody dicots (Wilson et al. 1994). Cixiids in the east apparently have a single generation per year (Bartlett et al. 2011). Cixiids are known vectors of phytoplasmas (“mycoplasma-like organisms”), the cause of lethal yellowing of palms in Florida and the Caribbean, with Haplaxius crudus implicated as one of the more important vectors (e.g., Tsai & Kirsch 1978, Howard & Thomas 1980).
The taxonomy of Cixiidae north of Mexico can be summarized as follows:
Bothriocerinae Muir, 1923
Bothriocerini Muir, 1923
Bothriocera Burmeister, 1835 (Type species Bothriocera tinealis Burmeister, 1835).
Cixiinae Spinola, 1839
Cixiini Spinola, 1839
Asotocixius Kramer, 1983 (Type species Asotocixius diopter Kramer, 1983).
Cixius Latreille, 1804 (Type species Cicada nervosa Linnaeus, 1758).
= Pseudocixius Caldwell, 1950a (Type species Pseudocixius bandarus Caldwell, 1950a); syn. by Kramer 1981a: 2.
Microledrida Fowler, 1904 (Type species Microledrida asperata Fowler, 1904).
Platycixius Van Duzee, 1914 (Type species Platycixius calvus Van Duzee, 1914).
Stegocixius Kramer, 1983 (Type species Stegocixius lochites Kramer, 1983)
Pentastirini Emeljanov, 1971
Melanoliarus Fennah, 1945b (Type species Oliarus (Melanoliarus) maidis Fennah, 1945a). (most Nearctic Oliarus species moved to Melanoliarus by implication Emeljanov 2001: 122).
Oliaronus Ball, 1934b (Type species Oliaronus tontonus Ball, 1934b).
Pentastiridius Kirschbaum, 1868 (Type species Flata pallens Germar, 1821).
Reptalus Emeljanov, 1971 (Type species Cixius quinquecostatus DuFour, 1833).
Oecleini Muir, 1922
= Myndini Muir, 1923; syn. by Emeljanov 1989: 62; also Holzinger et al. 2002.
Haplaxius Fowler, 1904 (Type species Haplaxius laevis Fowler, 1904) (listed as generic syn. of Myndus by Kramer, 1979: 303-304 in error).
Nymphocixia Van Duzee, 1923a (Type species Nymphocixia unipunctata Van Duzee, 1923a).
Oecleus Stål, 1862a (Type species Oecleus seminiger Stål, 1862a).
Key to the United States genera of Cixiidae (Modified from Kramer 1983).
1. Either antennae arising from elongated cup-like cavities anterior to eyes or vertex much narrowed, almost slit-like, and without strongly elevated lateral margins .... 2
1'. Without either of the above features .... 3
Lateral view of of head of Bothriocera cognita (left), and dorsal view of head of Oecleus borealis.
2. Vertex produced anteriorly with antennae arising in front of eyes, width of anterior coronal margin greater than its median longitudinal length ... Bothriocera Burmeister
2'. Vertex narrowly produced with antennae arising below eyes, width of anterior coronal margin much less than its median longitudinal length .... Oecleus Stål
3. With one or more spines on hind tibiae before apex .... 4
3'. Without spines on hind tibiae before apex .... 11
Hind leg of Haplaxius sp. (note absence of lateral spines on tibia).
Hind leg of Reptalus exoptatus (note spines on tibia)
Hind leg of Pentastiridius cinnamomeus.
4. Posterior margin of vertex angularly incised; mesonotum with five longitudinal carinae; but intermediate pair sometimes obsolete .... 5
4'. Posterior margin of vertex quadrately or roundly incised; mesonotum with three longitudinal carinae ..... 7
Head and thorax of Cixius pini (left) and Melanoliarus placitus (right)
5. Middle portion of costal area of each forewing thickened, dark, and setaceous; southwestern .... Oliaronus Ball
5’. Middle portion of costal area of each forewing hyaline or nearly so, without setaceous punctures .... 6
6. 10 or more teeth at the apex of the first hind tarsomere (see leg photos above) .... Pentastiridius Kirschbaum
6'. 10 or fewer teeth at the apex of the first tarsomere .... Melanoliarus Fennah & Reptalus Emeljanov
7. Eye elongated, about twice as long as wide; pronotum not strongly narrowed at middle; head porrect in lateral view .... Microledrida Fowler
7'. Without all of the above features .... 8
8. Submacropterous species, forewings just reaching or only slightly exceeding apex of abdomen, hindwings reduced to elongated scales .... Monorachis Uhler (in part)
8.’ Macropterous species, forewings extending much beyond apex of abdomen, hindwings fully developed .... 9
Lateral aspects of Monorachis sordulentus (top) and Pintalia vibex (bottom)
9. Forewings at rest roof-like in position with distal portions clearly separated; spines on hind tibiae conspicuous .... Cixius Latreille
9’. Forewings at rest vertical in position with distal portions broadly appressed; spines on hind tibiae less conspicuous .... 10
Dorsal aspect of Cixiius pini (top) and Pintalia vibex (bottom)
10. Mesonotum convex in lateral view; apical cells of forewing comparatively broad; frons with midlength and greatest width subequal .... Monorachis Uhler (in part)
10'. Mesonotum flat in lateral view; apical cells of forewing almost uniformly slender; frons with midlength exceeding greatest width .... Pintalia Stål
11. Middle portion of pronotum concealed by basal portion of vertex; head in lateral view broadly rounded .... Nymphocixia Van Duzee
11'. Middle portion of pronotum exposed; head in lateral view not broadly rounded .... 12
Dorsal and lateral aspects of Nymphocixia unipunctata.
12. Pronotum unusually large and concealing all but tips of tegulae .... Stegocixius Kramer.
12'. Pronotum not unusually large, most of tegulae exposed .... 13
Dorsal aspect of Stegocixius lochites (Holotype).
13. Carina on longitudinal midline of frons absent .... Platycixius Van Duzee
13'. Carina on longitudinal midline of frons present .... 14
Frontal aspect of Platycixius calvus (left) and Haplaxius radicans (right).
14. Vertex with distinct carina on both longitudinal midline and between anterior portions of eyes; longitudinal midlength of mesonotum at least 3x longitudinal midlength of vertex; southwestern .... Asotocixius Kramer
14'. Vertex without distinct carina on both longitudinal midline and between anterior portions of eyes; longitudinal midlength of mesonotum about 2x or less longitudinal midlength of vertex, widespread .... Haplaxius Fowler
Dorsal aspect of Haplaxius radicans (top) and Astrocixius diopter (below)
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