Two new genera of Agathidiini are described and revised: Gelae Miller and Wheeler, new genus and Decuria Miller and Wheeler, new genus. Gelae differs from other agathidiines by having 11 antennomeres, a distinctly 3-segmented antennal club, no supraocular carina, no postocular temporum, 5–4–4 female tarsal formula and obsolete dorsal punctation, or, if present, inconspicuous and not serially arranged. Decuria differs from other agathidiines by having 10 antennomeres. The dramatically poor taxonomic condition of genera in the Agathidiini is discussed and problems are identified. A key to the genera of Agathidiini is presented. The following new combinations are proposed: Gelae parile (Fall), new combination, G. parvulum (LeConte), new combination, and G. cognatum (Matthews), new combination. Each are transferred from Agathidium Panzer. The following new species are described: Gelae rol, new species, G. fish, new species, G. donut, new species, G. baen, new species, G. belae, new species, and Decuria newtoni, new species. A lectotype is designated for Agathidium parile Fall. Notwithstanding certain recent advances in the classification of genera of the leiodid tribe Agathidiini (Angelini and Peck 2000; Newton 1998), monophyly of some of these genera and proposed relationships among them remain in serious doubt. A particular problem is represented by the genus Agathidium Panzer, which is a huge group of several hundred species without a single known unambiguous synapomorphy. The current definition of the genus is based on a character combination with conspicuous exceptions. The genus is defined, in part, as having a distinct 3-segmented antennal club, the clypeus not protuberant, and punctured elytral striae absent. However, some (e.g., Ag. rusticum Fall) have a relatively prominent 5-segmented club, several (e.g., Ag. athabascanum Fall, Ag. laetum Fall, the Ag. sexstriatum-group) have rather prominently anteriorly-protruding anterior clypeal margins and others (e.g., the Ag. sexstriatum-group and several members of the Ag. pulchrum-group) have longitudinally serial punctures on the elytra (Miller and Wheeler in press; Wheeler and Miller in press). The problem is not necessarily the misplacement of species in this genus since many of these species strongly resemble other, more ‘‘typical’’ Agathidium in other less general characters. Other genera have different problems. The genus Anisotoma Panzer appears to be united by apparently plesiomorphic features including a typical leiodid 5-segmented antennal club, protuberant anterior clypeal margin, longitudinally striate elytra (absent in some Anisotoma), and lack of a postocular temporum and carina. Other genera, including Sphaeroliodes Portevin, Stetholiodes Fall, and Pseudoagathidium Angelini are apparently ambiguously defined or are based on characters that vary within the genus Agathidium such that even writing an adequate key is quite difficult. In a recent paper describing a new agathidiine genus, Angelini and Peck (2000) presented a number of characters used to distinguish genera of the tribe, a key to the genera, and a proposal of the phylogeny. However, there are a number of problems with their analysis. For example, the topology they present is not the most parsimonious. When their character matrix is analyzed using all additive character states (as they did) using NONA and the commands ‘‘hold/20,’’ ‘‘mult*20,’’ for tree