Grossicis, a new genus of Neotropical minute tree-fungus beetles (Coleoptera: Ciidae), with a detailed discussion on its systematic position in the family.

Grossicis gen. nov. is described based on G. diadematus (Mellié, 1849) comb. nov., the type species, and G. laminicornis sp. nov. from Brazil. Diagnostic characters of the genus include the apical maxillary palpomere abruptly expanded with sensilla distributed along the apical margin, dual elytral punctation, elytral sutural flange diverging near apex, prosternum carinate, protibial apex bearing a row of spines and outer apical angle with a conspicuous tooth, ovipositor bearing well developed gonostyli with almost half the length of gonocoxites, baculum of each proximal gonocoxite oblique, and anterior apex of each paraproctal baculum contiguous and joined to each proctigeral baculum, their limits being barely discernible, forming an arc anteriorly. Comparisons were made with other 37 ciid genera, and the new genus is provisionally placed in Ciini. A key to species of Grossicis gen. nov. is provided, together with the description of external morphology of adults, as well as the morphology of male and female terminalia of both species.