Subgenus Gonatocerus ( Lymaenon Walker, 1846), stat. rev.

Lymaenon Walker 1846: 49 –50. Type species: Lymaenon acuminatus Walker, by subsequent designation by Gahan & Fagan 1923: 82.

Rachistus Foerster 1847: 203 . Type species: Ooctonus litoralis Haliday, by subsequent designation by Gahan & Fagan 1923: 128.

Rhachistus Dalla Torre 1898: 429 . Unjustified emendation of Rachistus Foerster.

Oophilus Enock 1909: 458 . Type species: Oophilus longicauda Enock, by monotypy.

Agonatocerus Girault 1913a: 276 . Type species: Agonatocerus humboldti Girault, by original designation.

Gonatoceroides Girault 1913b: 255 (as subgenus of Gonatocerus). Type species: Gonatocerus (Gonatoceroides) australicus Girault [as australica], by original designation.

Lymaenon Walker ( litoralis species group): Debauche 1948: 80, 82; Debauche 1949: 27.

Lymaenon Walker (unnamed group 4): Debauche 1948: 82.

Decarthrius Debauche 1949: 21 –22. Type species: Decarthrius straeleni Debauche, by original designation. Syn. n. (from previous synonymy under Gahanopsis by Annecke & Doutt 1961: 13).

Gonatocerus Nees (contortivena species group): Debauche 1949: 26.

Gonatocerus Nees ( acuminatus species group [= Oophilus Enock]): Debauche 1949: 26, 33.

Oophilus Enock: Kryger 1950: 79 –81.

Gonatocerus ( Gonatocerus Nees): De Santis 1967: 103–105 (in part).

Gonatocerus ( Lymaenon Walker): Herting 1972: 14.

Gonatocerus Nees ( litoralis species group): Matthews 1986: 216 (key), 222–223; Huber 1988: 30 –32; Yoshimoto 1990: 37 –38; Zeya & Hayat 1995: 91 –94.

Gonatocerus Nees ( straeleni species group, without a formal synonymy of Decarthrius [then a synonym of Gahanopsis Ogloblin] under Gonatocerus): Huber 1988: 24; Yoshimoto 1990: 37.

Diagnosis. Face with subantennal sulci widely separated from each other at junction with clypeus; back of head without sutures; pronotum divided into 2 lobes widely separated by lightly sclerotized median area, except narrowly separated in a few Afrotropical species and median area sometimes strongly sclerotized in some Australasian species; female funicle usually 8-segmented, rarely 7-segmented (mostly in some Afrotropical species); dorsellum strap-like, with posterior margin straight and parallel with anterior margin; propodeum with submedian lines instead of a median carina or submedian carinae (except in some Afrotropical species) and the area between them flat and often bearing minute spicules; forewing with cubital row (at least) of setae extending to base of marginal vein (except in some Afrotropical and Australasian species).

Distribution. Cosmopolitan.

Hosts. In the New World the known, reliable host records of G. ( Lymaenon) are from eggs of Cicadellidae .

Comments. Gonatocerus (Lymaenon) straeleni (Debauche), comb. n. from Gahanopsis Ogloblin, clearly belongs to G. ( Lymaenon), hence the proposed synonymy of Decarthrius Debauche. The female antenna of this species has 7 funicle segments (apparently due to fusion of F1 and F2), all of which are much longer than wide. All other structural features match those of G. ( Lymaenon). Males of G. straeleni were previously unknown, the antennae of males from Kenya * [UCRC] have a long, 11-segmented flagellum.

Gonatocerus (Lymaenon) anthonomi Girault was mentioned by De Santis (1979) from Mexico but without indicating any locality; it is not considered in this review because we have not seen any determined specimens from the Neotropical part of Mexico. The senior author found in USNM a slide-mounted female specimen labeled: “ Gonatocerus ♀ anthonomi Gir. Gahan. On redishes from Juarez, Mex. Oct. 13:42. R.O. Collier. El Paso 35902”. According to the label, it was intercepted at the USA-Mexico border in El Paso, Texas, USA; the origin was Ciudad Juárez, Chihuahua, which is in the Nearctic part of Mexico. This specimen, which belongs to G. (Lymaenon) litoralis (Haliday), was the likely reason for the above-mentioned record by De Santis (1979).