Chiasmini Distant, 1908

Zahniser, James N. & Dietrich, Chris H., 2013, A review of the tribes of Deltocephalinae (Hemiptera: Auchenorrhyncha: Cicadellidae), European Journal of Taxonomy 45, pp. 1-211 : 53-56

Chiasmini Distant, 1908

Fig. 14

Type genus: Chiasmus Mulsant & Rey, 1855 .

= Doraturini Emeljanov, 1962 .

= Listrophorini Boulard, 1971 syn. nov.

= Paraphrodini Linnavuori, 1979 .

Diagnosis

Chiasmini are small to medium sized leafhoppers, usually white, stramineous, green, brown, grey, or black in coloration, and sometimes iridescent. They can be identified by the tapering or parallelsided clypellus, aedeagus hinged at the base (hinge usually but not always present), ovipositor usually extending far beyond the pygofer, first valvula dorsal sculpturing pattern maculose to granulose and usually submarginal, first valvula without distinctly delimited ventroapical sculpturing, and second valvula teeth obliquely triangular and serrated.

Description

HEAD. Head subequal to or wider than pronotum. Discal portion of crown glabrous with radial or longitudinal striae or shagreen. Anterior margin of head shagreen, glabrous, irregularly textured, or foliaceous. Frontoclypeus not tumid; texture shagreen or glabrous. Clypellus parallel-sided or tapering apically; apex following or slightly surpassing normal curve of gena. Lorum wider than, subequal to, or distinctly narrower than clypellus near base. Antennal bases near middle or posteroventral (lower) corners of eyes. Antennae short, less than 1.5 x width of head. Gena obtusely incised or strongly incised (nearly forming right angle) laterally; with or without ( Baileyus , Gurawa , Listrophora , some Chiasmus ) fine erect seta beside laterofrontal suture.Antennal ledge absent or weakly developed (carinate or weakly carinate). Ocelli absent, reduced, or present; close to or distant from eyes; on anterior margin of head or on crown ( Chiasmus ).

THORAX. Pronotum lateral margin carinate or not carinate; lateral margin shorter than basal width of eye.

WINGS. Forewing brachypterous to macropterous; if macropterous then appendix large and extending around wing apex; with 3 anteapical cells or with 2 anteapical cells; veins not raised or veins distinctly raised or carinate ( Baileyus , Gurawa , Paraphrodes ); without reflexed costal veins; A1-A2 crossvein absent.

LEGS. Profemur with AM1 seta only or rarely with an additional proximal seta ( Doraturopsis Lindberg , Protochiasmus Zahniser ); intercalary row with one row of five or more fine setae or intercalary row reduced or absent; row AV with short, stout setae or with relatively long macrosetae. Protibia dorsal

surface rounded, convex. Metafemur apex macrosetae 2+1, 2+2, 2+1+1, or 2+2+1. Metatarsomere I not expanded apically or expanded apically; plantar setae simple, tapered.

MALE GENITALIA. Valve articulated with pygofer; lateral margin short, articulating with pygofer at a point. Pygofer basolateral membranous cleft present or absent, not membranous; macrosetae absent, reduced (≤ two rows) or well differentiated into several rows. Subgenital plates free from each other; articulated with valve; macrosetae absent or present, scattered, irregularly arranged, or uniseriate laterally. Style broadly bilobed basally, median anterior lobe pronounced. Basal processes of the aedeagus/connective absent or reduced. Aedeagus often with or sometimes without ( Baileyus , Leofa , Gurawa , Paraphrodes ) basal hinge; with a single shaft and gonopore. Connective anterior arms somewhat divergent, Y - or U -shaped, or anterior arms closely appressed anteriorly; articulated with aedeagus.

FEMALE GENITALIA. Pygofer with macrosetae reduced or absent or with numerous macrosetae. Ovipositor usually protruding far beyond pygofer apex (not protruding in Baileyus , Gurawa , Omaranus , Paraphrodes ). First valvula not strongly convex; dorsal sculpturing pattern granulose or maculose; sculpturing submarginal; without distinctly delimited ventroapical sculpturing. Second valvula abruptly broadened medially or subapically; without dorsal median tooth; dorsal teeth present on apical 1/3 or more; teeth obtusely triangular and serrated.

Geography and ecology

Distribution: cosmopolitan. Nearly all species are grass or sedge feeders, and they are typical members of the grassland faunas of the world. Driotura spp. have been collected from Asteraceae . Nephotettix virescens ( Distant, 1908) and some other Nephotettix spp. are agricultural pests and transmit tungro virus of rice in southeast Asia, and can cause severe economic loss.

Remarks

Chiasmini contains 21 genera and 317 species. The tribe appears to be most closely related to Stenometopiini ( Zahniser 2008a; Zahniser & Dietrich 2010) with which it shares some similarities of the ovipositor and male pygofer. Phylogenetic analyses sometimes resolve it as sister to Stenometopiini, and also suggest that the two tribes are related to Eupelicini, Drakensbergenini, and Evinus . In the phylogenetic analyses here, the tribe was resolved as monophyletic in ML and Bayesian analyses, but in parsimony analyses it was monophyletic with the exception of Protochiasmus , which was resolved, sister to Evinus but with little or no branch support. The placement of Gurawa in Chiasmini is supported by these analyses and the morphologically similar Baielyus and Paraphrodes ( Zahniser 2008a, 2011) are also included.

For the first time, molecular data for Listrophora were included in phylogenetic analyses and the genus was found with very strong branch support to be related to Chiasmini . The morphological characters of the male and female genitalia of Listrophora (aedeagus hinged, first valvula dorsal sculpturing pattern granulose and submarginal, second valvula with distinct serrated oblong and triangular teeth) match those of other Chiasmini , despite the bizarre and unique diamond-shaped process of the head, which led Boulard (1971) to place it in a separate tribe. In our analyses it was found to be closely related to Gurawa within Chiasmini , with which it shares the raised or carinate veins of the forewing. Listrophorina was previously included as a subtribe of Eupelicini ( Zahniser & Dietrich 2010) but is synonymized here with Chiasmini .

Nephoris is transferred to the tribe based on the figures published by Jacobi (1912). N. chalybaea Jacobi, 1912 appears similar to Leofa thompsoni Zahniser, 2008 which was also described from central Africa. Attempts to locate the type were unsuccessful, but for now it is considered a valid genus pending further study.

Selected references

Vilbaste (1965), Ross (1968), Boulard (1971), Blocker (1983), Blocker & Johnson (1988a, b, 1990a, b, c), Emeljanov (1999), Dmitriev (2003), Zahniser & Hicks (2007), Zahniser (2008a, b, 2011), Duan et al. (2009), Duan & Zhang (2012a, b, c).

Notes on illustration ( Fig. 14 )

The specimens figured are identified as Chiasmus sp. from W. Cape Province, South Africa. The species identity of Chiasmus specimens is difficult to determine given the variability in some described species and because of the relatively uniform male genitalia among species. C. varicolor (Kirkaldy, 1906) is known from Australia and South Africa, C. undulatus Theron, 1982 is also known from South Africa, and C. katonae (Melichar, 1908) is known from Tanzania. The species figured is similar to C. katonae but differs in size, surface shape of the crown, and coloration. The genus should be revised and species concepts reevaluated to improve the taxonomy and allow for easier identification.

Included genera

Aconura Lethierry, 1876

Aconurella Ribaut, 1948

Athysanella Baker, 1898

Baileyus Singh-Pruthi, 1930

Chiasmus Mulsant & Rey, 1855

Doratura Sahlberg, 1871

Doraturopsis Lindberg, 1935

Driotura Osborn & Ball, 1898

Exitianus Ball, 1929

Gurawa Distant, 1908

Icaia Linnavuori, 1973

Leofa Distant, 1918

Listrophora Boulard, 1971 placement nov. (previously placed in Eupelicini: Listrophorina)

Nephoris Jacobi, 1912 placement nov. (transferred from Athysanini )

Nephotettix Matsumura, 1902

Omaranus Distant, 1918

Paraphrodes Linnavuori, 1979

Picchusteles Linnavuori & DeLong, 1976

Protochiasmus Zahniser, 2010

Stenogiffardia Evans, 1977

Zahniserius Duan & Zhang, 2012

Figures

Fig. 14. Chiasmini. Chiasmus sp. (see note under Chiasmini on identification of species of Chiasmus). A–I. Standard views (see Material & Methods).