Genus Monalonion Herrich-Schaeffer, 1850

Monalonion Herrich-Schaeffer, 1850:168 .

Type species: Monalonion parviventre Herrich-Schaeffer 1850:168 . Monotypic. Monalonion: Carvalho 1972: 120 (historical review, diagnosis, list of species, synonymies, key to species); Lavabre 1977A:332 (discussion, plant resistance); Lavabre 1977B:140 (discussion, economic importance); Gamboa et al. 2020:145 (historical, taxonomic review, phylogeny, distribution, hosts, discussion).

Diagnosis. Elongated body; head wider than long; eyes occupying the anterior region of the head; posterior region of the head tapering towards the thorax, making a short neck; The labium not reaching the middle coxa. Antennal segment I very short (length 1.5–3x the width), pear-shaped, and shorter than the length of the head; antennal segments II–IV filiform; pronotum hemispheric; and hemelytra fully covering the abdomen, with the length of the membrane being nearly half the length of hemelytron, with a sharp and prominent vein. (Herrich-Schaeffer 1850; Namyatova & Cassis 2016; Namyatova et al. 2016; Gamboa et al. 2020).

Remarks. The identification of Monalonion species is challenging. More research is needed to fully comprehend the interspecific and intraspecific morphological variation. Because color shows high intraspecific variation in individuals and sexes (sexual dimorphism), it should be reconsidered as a species-defining character. A taxonomic review of the genus based on morphological as well as molecular characters is needed to clarify the limits between species and their phylogenetic relationships.