LYMAENON Walker, 1846

(Figs 545–560)

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

Rachistus Foerster, 1847: 203 . Type species: Ooctonus litoralis Haliday, 1833, by subsequent designation by Gahan & Fagan, 1923: 128. De facto synonymy under Lymaenon by Huber, 2015: 41.

Rhachistus [sic]: Dalla Torre, 1898: 429. Unjustified emendation.

Oophilus Enock, 1909: 458 . Type species: Oophilus longicauda Enock, 1909, by monotypy. De facto synonymy under Lymaenon by Huber, 2015a: 41.

Agonatocerus Girault, 1913 [149]: 276. Type species: Agonatocerus humboldti Girault, 1913, by original designation. De facto synonymy under Lymaenon by Huber, 2015a: 41.

Gonatocerus (Gonatoceroides) Girault, 1913 [155]: 255. Type species: Gonatocerus australicus Girault, 1913, by original designation. De facto synonymy under Lymaenon by Huber, 2015: 41.

Decarthrius Debauche, 1949: 21 . Type species: Decarthrius straeleni Debauche, 1949, by original designation. De facto synonymy under Lymaenon by Huber, 2015a: 41.

Diagnosis. Body length 560–1770 μm. Ocellar triangle with 3 or, rarely, 4 setae between lateral ocelli (Fig. 547); pronotal lobes separated by a membranous gap (Fig. 551); mesothoracic spiracle much larger than propodeal spiracle (Fig. 552); dorsellum strap-like, with anterior and posterior margins parallel (Figs 551, 552); stigmal vein with apex truncate (Fig. 554); propodeum with parallel or slightly converging submedian lines, often with spicules between them (Fig. 551).

Discussion. Among the four genera in the Nearctic ( Cosmocomoidea, Gastrogonatocerus, Gonatocerus, and Lymaenon) that share the following combination of features: tarsi 5-segmented, funicle 8-segmented, face with subantennal sulci, and parastigma with hypochaeta about midway between proximal and distal macrochaetae (Huber 2015a), Lymaenon is superficially most similar to Gonatocerus because of its relatively narrow fore wing usually uniformly covered with microtrichia from base of parastigma to wing apex but sometimes with a clear area between parastigma + stigma and cubital line of microtrichia (Fig. 554); otherwise it differs especially in mesosomal structure.

Nearctic hosts. Hemiptera: Cicadellidae, Membracidae .

Important references. Triapitsyn (2013a), Triapitsyn (2013b), and Triapitsyn et al. (2010) treated Palaearctic, Nearctic and Neotropical species, respectively.