North American Derbidae
Derbidae consist of 160 genera and 1,679 species currently known (Bourgoin 2016), making them the third most species-rich family of planthoppers (after Cixiidae and Delphacidae). Derbidae is represented north of Mexico by 14 genera and 70 species. All genera of Derbidae north of Mexico, except Apache, have additional species found in the Neotropics. Like most other planthopper taxa, Derbidae tend to have the highest species richness in the tropics, although tropical forms are very poorly studied. The higher taxonomy of Derbidae was revised by Fennah (1952), and more recently by Emeljanov (1996). Their family composition has seldom been questioned.
Derbidae is most diverse in the east, particularly the southeast with 13 genera and 55 species, but this family is irregularly reported in the literature and records are conspicuously sparse in some states.
Many derbids are very unusual appearing insects and are easily recognized to family and beyond. In contrast, Cenchreini and Cedusinae are much less unusual appearing, and can be very challenging to identify beyond genus. Derbids generally can be recognized by having the row of spines on the second hind tarsal segment and having the apical segment of the beak short. The head is compressed – slightly or greatly – with the median carina obsolete, and male parameres elongate (projecting beyond the anal segment). Derbinae and Otiocerinae are very unusual appearing with greatly compressed heads and wings much longer than, and usually held parallel to, the body. Some (viz. Paramysidia and Dysimia) hold their wings outstretched in a moth-like pose (like the top photo on this page). Cenchreini and Cedusinae have their heads less compressed and wings shorter (although still exceeding the abdomen).
O’Brien (1982) revised Fennah’s (1952) key to Cedusini (as Cenchreini) to include New World genera only, and provided a checklist of New World species of this tribe excluding Cedusa. Mysidiini were revised by Broomfield (1985), but this group includes only 2 species north of Mexico and Emeljanov (1996) considered Mysidiini as part of Derbini. The large genus Cedusa was revised by Flynn & Kramer (1983) and Kramer (1986). Species of Cedusa are very similar externally and require examination of male genitalia for identification. Omolicna consists of 19 mostly Neotropical species, which are very similar externally and also require examination of male genitalia. Caldwell (1944) considered Omolicna of Mexico (as Phaciocephalus), but species north of Mexico have not been treated consistently among authors. The species and geographic limits of U.S. Omolicna need review. Aside from Cedusa and Omolicna, many eastern species can be identified using Metcalf (1923) or Bartlett et al. (2011). Recently, a new species of Omolicna was described from Florida as a possible vector of Texas Phoenix Palm Decline, caused by a phytoplasma (Wilson et al. 2014), and a key to most U.S. species of Omolicna was included.
Immature derbids are fungus feeders and have been reared from logs (Willis 1982, Wheeler & Wilson 1996) and decaying organic debris (Howard et al. 2001). Adults are sometimes found in logs or are associated with monocots, presumably near their larval habitat (Wilson et al. 1994, Howard et al. 2001). Adults of most species have been reported on only a single host (Wilson et al. 1994), but the significance of adult host affinities is not clear. Adults often gather under broad leaves, presumably a behavior to protect their fragile wings. There are no well documented pests, but 20 species have been recorded as potentially injurious to economic plants (Wilson & O’Brien 1987), but are increasingly being considered as possible vectors of palm diseases. Cedusa has been documented as carrying phytoplasmas (Brown et al. 2006), and (as noted above), Omolicna is a suspected vector of the phytoplasma causing Texas Phoenix Palm Decline.
The genera of derbids found north of Mexico are as follows (a key to genus will be presented in a later update; an online checklist to New World Derbidae and key to genera of New World Cenchreini (sensu Fennah 1952) under development.
Cedusinae Emeljanov, 1992
Cedusini Emeljanov, 1992
= Cenchreini Muir 1917 sensu Fennah 1952, Broomfield 1985 in part; status by Emeljanov 1996.
Cedusa Fowler, 1904 (Type species Cedusa funesta Fowler, 1904)
Derbinae Spinola, 1839
Derbini Spinola, 1839
= Mysidiini Broomfield, 1985; syn. by Emeljanov 1996: 74.
Dysimia Muir, 1924 (Type species Dysimia maculata Muir 1924).
Paramysidia Broomfield, 1985 (Type species Mysidia mississippiensis Dozier, 1922).
Cenchreini Muir, 1917
Neocenchrea Metcalf, 1923 (Type species Cenchrea heidemanni Ball, 1902b).
Omolicna Fennah, 1945a (Type species Omolicna proxima Fennah, 1945).
Persis Stål, 1862c (Type species Persis pugnax Stål, 1862c).
Otiocerinae Muir, 1917
Otiocerini Muir, 1917
Anotia Kirby, 1821 (Type species Anotia bonnetii Kirby, 1821).
= Amalopota Van Duzee, 1889 (Type species Amalopota uhleri Van Duzee 1889); syn. by Fennah 1952: 152.
Apache Kirkaldy, 1901a (Type species Hynnis rosea Burmeister 1835, jr. syn. of Otiocerus degeerii Kirby 1821).
Otiocerus Kirby, 1821 (Type species Otiocerus stollii Kirby 1821).
Sayiana Ball, 1928 (Type species Anotia sayi Ball, 1902b).
Shellenius Ball, 1928 (Type species Otiocerus ballii McAtee 1923).
Patarini Emeljanov, 1996
Patara Westwood, 1840 (Type species Patara gutata Westwood, 1840) .
Key to genera of Derbidae north of Mexico (Bartlett et al. 2014 with figure references removed, modified from Metcalf 1923).
1. Fragile forms, pronotum not modified into cup-like structure behind antennae; frons greatly compressed, and often anteriorly projecting; clavus usually open (combined CuP + 2A vein curving to follow wing margin, not reaching margin within claval area) … 5
1.’ More robust forms, pronotum modified into cuplike structure, often anteriorly projecting beneath antennae ; frons moderately compressed; clavus closed (combined CuP + 2A vein not curving to follow wing margin, but reaching wing margin within claval area) … 2
2. Subantennal process large, extending laterally from gena, completely subtending antennae as a shelf; no sensory pits on head or wings; color (usually) uniformly near black, dark blue, or deep grey, infrequently near white with yellowish-brown patches … Cedusa Fowler
2.’ Subantennal process extending from pronotum smaller; sides of vertex and second claval vein with sensory pits; color usually orange to pale … 3
3. Media with more than two branches, connected to cubitus by crossvein; size less than 6 mm, usually distinctly orangish; projections of pronotum partially subtending antennae … Omolicna Fennah
3.’ Media and cubitus each with two branches, not connected by crossveins; size over 7 mm; pronotum not subtending antennae … 4
4. Lateral margins of pronotum strongly foliate posterior to antennae; pygofer without medioventral process; eastern … Neocenchrea Metcalf
4.’ Lateral margins of pronotum not or weakly foliate; pygofer with medioventral process; southwestern … Persis Stål
5. Antennae with appendages … 6
5.’ Antennae lacking appendages … 8
6. General color rose or reddish, wings entirely rose (see above); in lateral view, dorsum of head rather sinuate and dorsal margin of wings in repose sharply angled dorsal in apical third; forewings with dusky spots in most cells … Apache Kirkaldy
6.’ General color usually white or yellow, rarely predominately reddish (e.g., Otiocerus coquebertii, O. stollii); in lateral view, dorsum of head flat or rounded), dorsal margin of wings nearly straight; forewings usually without dusky spots in most cells (although some dark spots may be present) … 7
7. In lateral view, demarcation between vertex and frons obtusely angular … Otiocerus Kirby
7.’ In lateral view, demarcation between vertex and head smoothly rounded … Shellenius Ball
8. In lateral view, head projecting in front of eyes for a distance subequal to width of eyes … 9
8.’ In lateral view, head projecting in front of eyes for a distance of less than half width of eyes …. 10
9. Costal margin at base slightly expanded, at most into triangle longer (along length of wing) than wide; antennae with second segment constricted on one side apically. … Anotia Kirby
9.’ Costal margin expanded to a free appendage half as wide as wing at that point; second segment of antennae strongly flattened, as wide as width of eye … Sayiana Ball
10. Clavus open … 11
10.’ Clavus closed … 12
11. First cell of forewing distinctly triangular, widest at midlength, narrowed both anteriorly and posteriorly; dark markings on wing mostly along veins; hindwings narrow, strap-shaped, with two longitudinal veins … Mula Ball
11.’ First cell of forewing distinctly elongate, widest near apex; dark markings on wing in cells and along veins; hindwings wider … Sikaiana Distant
12. Second antennal segment flattened, longer than width of head across eyes (Fig. 65J), male antennae longer than those of female; size small, 5 mm or less; wings usually tectiform … Patara Westwood
12.’ Second antennal segment globular, shorter than width of head across eyes; often larger than 5 mm; wings often held outstretched … 13
13. Cubital vein of forewing three branched (CuA and M4 fused basally); smaller, near 5 mm … Dysimia Muir
13.’ Cubital vein of forewing four branched (CuA and M4 basally connected by crossvein); larger, near 7 mm … Paramysidia Broomfield
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Last edited 7 Oct. 2019