1	Size small, TL = 1.3 mm. Elytral punctation almost entirely indistinct, except discal row and submargin of elytral suture with distinct punctures, with very fine scattered setose punctures near lateral margins; elytral surface with microreticulation consisting of round, isodiametric cells, somewhat scale-like in appearance. Head appendages short, antennomeres VI–X wider than long; apical palpomeres distinctly bifurcate with enlarged sensory fields. Aedeagus as in Fig. 2 of Guimarães and Ferreira-Jr (2019); median lobe with large base and very large processes and hooks. Male pro- and mesotarsal claws short, anterior protarsal claw expanded at base. Known only from high elevation hygropetric habitats in Minas Gerais, Brazil	N. teramnus
–	Size variable, ca. 1.2–1.9 mm. Elytral punctation and microsculpture variable. Antennomeres usually longer than wide; apical palpomeres variable. Median lobe of aedeagus without conspicuous hooks or large processes (e.g. Figs 6, 7). Male pro- and mesotarsal claws variable. Habitat preference variable	2
2	Dorsal (outer) margin of protibia without notable robust seta at or near mid-length (Fig. 2a). Eyes large relative to head capsule (Fig. 5), HW/EW ≥ 2.0. Elytra with notable contrasting dark and light colors (Fig. 5a, c). Profemur with > 3 distinct closely spaced setae on anteroventral margin (Fig. 2a); posteroventral margin of male profemur lacking notable protuberance, only weakly angled near mid-length (Fig. 2a); male protarsal claws very small, distinctly shorter than half the length of protarsomere V, anterior protarsal claw bifurcate, branching dorsally (Figs 8, 9)	josiahi group
–	Dorsal margin of protibia with a robust seta at or near mid-length (often two in females), at least as long as most dorsal seta on dorsoapical angle (Fig. 2b–f). Eyes smaller, HW/HW < 2.0. Elytra with or without contrasting colors. Profemur with < 3 closely-spaced setae on anteroventral margin; posteroventral margin of male profemur with notable protuberance or acute angle at ca. mid-length; male protarsal claws variable, anterior claw length almost always at least half the length of protarsomere V, almost always larger than female claws, sometimes bifurcate	3
3	Noterid platform with angles of posterior lobes squared or rounded (Fig. 4b–e)	4
–	Noterid platform with angles posterior lobes acutely angled (as in Fig. 4a, f–l)	5
4	Elytral surface impunctate to weakly punctate, punctures usually inconspicuous and sporadic under normal magnification, except for discal series; microreticulation variably impressed, consisting of small, round, isodiametric cells, giving the appearance of small scales. Body form variable, but usually oblong, less attenuated posteriorly (Fig. 1a–c). Elytral color uniform, brown, sometimes shiny, not iridescent or only weakly so	nanulus group
–	Punctation distinctly present and often dense on posterior half of elytra, punctures finely to moderately impressed, bearing short setae, often extending on to anterior half of elytra; microreticulation variably impressed, consisting of fine mesh-like reticulation. Body form variable, but more elongate and attenuated posteriorly (Fig. 1g–i). Color variable, but elytra of mature specimens of most species with darker triangular area medially at base (Fig. 1g, i); in most species, dorsal surface very shiny and iridescent	meizon group (in part)
5	Color uniformly brown. Elytral surface with microreticulation variably impressed, consisting of small, round, isodiametric cells, giving the appearance of fine scales, somewhat shiny, but never iridescent; punctation variable. Males with anterior protarsal claw bifurcate or branched (as in Fig. 8a)	6
–	Color variable, uniform or bicolorous. Elytral surface with microreticulation variably impressed, consisting of fine mesh-like reticulation, sometimes iridescent. Males with protarsal claws never bifurcated or branched	7
6	Body form oblong, rounded posteriorly (as in Fig. 1l or similar to nanulus group, for example, Fig. 1d). Elytral surface weakly punctate. Median lobe in lateral view as in Fig. 12b. New World	N. brevicornis Sharp, 1882
–	Body form ovoid, more elongate, more attenuated posteriorly (as in Fig. J). Elytral surface weakly to moderately punctate. Median lobe different. Indomalaya and Oceania	tenellus group
7	Protibia with robust seta of dorsal margin distinctly distad of half-length of outer margin, approximately at 2/3 margin length (Fig. 2e), distance between robust seta and dorsoapical angle distinctly shorter than distance between robust seta and first seta from protibial insertion. Dorsal coloration uniformly brown or bicolorous (Fig. 1d–f), with pronotum distinctly lighter than head and elytra. Elytral surface matte to somewhat shiny and iridescent	traili group
–	Protibia with robust seta of dorsal margin approximately at half-length of outer margin, distance between robust seta and dorsoapical angle subequal to distance between robust seta and protibial insertion (Fig. 2d). Color variable, but elytra of mature specimens of most species with darker triangle medially at base (Fig. 1g, i). Most species with elytral surface very shiny, iridescent	meizon group (in part)