1	Outer subhumeral stria complete	2
–	Outer subhumeral stria abbreviated, present only in posterior half	6
2	1st abdominal ventrite with single lateral stria; propygidium with larger, sparse punctures, their diameters equal to about one-fifth of propygidial length; lateral submarginal pronotal stria distant from margin; prosternal carinal striae widely separated, weakly converging, almost parallel; Costa Rica	Operclipygus limonensis sp. n. [not belonging to the Operclipygus hospes group, but also keyed here as it is very similar]
–	1st abdominal ventrite with two lateral striae; propygidium with much smaller punctures, their diameters less than one-eighth of propygidial length	3
3	Species from Central America	4
–	Species from South America	5
4	Outer lateral stria of 1st abdominal ventrite complete, reaching posterior margin; pronotum with at least a few coarse lateral punctures; lateral metaventral stria extending toward outer corner of metacoxa; pygidial punctures larger, shallow, ocellate (Fig. 39F)	Operclipygus fusistrius sp. n.
–	Outer lateral stria of 1st abdominal ventrite abbreviated, sinuate near midpoint of ventrite length around postcoxal fovea; pronotum lacking coarse lateral punctures; metaventral stria extending obliquely toward metepisternum; pygidial punctures small, deep (Fig. 41C)	Operclipygus ibiscus sp. n.
5	Propygidial punctures small, deep, and dense, separated by less than one-half puncture diameter (Fig. 39B); marginal pygidial sulcus relatively fine; apices of 4th and 5th elytral striae free (Fig. 39A); W Amazonia	Operclipygus diffluens sp. n.
–	Propygidial punctures sparser (Fig. 39D); marginal pygidial sulcus deep and coarse; apices of 4th and 5th dorsal striae confluent (Figs 39C–D); SE Andean slopes	Operclipygus confluens sp. n.
6	Marginal sulcus of pygidium absent	7
–	Marginal sulcus of pygidium present	8
7	Sternite 8 of male genitalia with apices narrow, parallel, only weakly curved downward (Fig. 43B); aedeagus narrow (Fig. 43I); Central America	Operclipygus gratus sp. n.
–	Sternite 8 of the male genitalia with apices broader, divergent, strongly downturned (Fig. 43F); aedeagus wider (Fig. 43K); W Amazonia	Operclipygus rileyi sp. n.
8	Pygidial sulcus normally developed, well-incised (may be inconspicuous in specimens with pygidium retracted), rarely abbreviated basally	10
–	Pygidial sulcus very thin, striiform, complete or not	9
9	Lateral submarginal pronotal stria complete, well impressed; numerous coarse lateral pronotal punctures present; sutural stria obsolete in anterior one-fourth	Operclipygus sp. [a probably distinct entity from French Guiana, represented only by females, which we have chosen not to describe at this time]
–	Lateral submarginal pronotal stria represented by short, thin fragments near anterior corners; sutural stria complete or only very slightly abbreviated at base (Fig. 37A)	Operclipygus inquilinus sp. n.
10	Pronotum without lateral submarginal stria, with at most minute anterior fragments	11
–	Pronotum with lateral stria present, at least as short anterior stria	12
11	Recurved arms of anterior submarginal pronotal stria nearly reaching pronotal midpoint (Fig. 45A); mesometaventral stria forming wide trapezoid on mesoventrite; ground punctation of body relatively faint; prosternal carinal striae united posteriorly	Operclipygus impositus sp. n.
–	Recurved arms of anterior submarginal pronotal stria shorter, not reaching beyond anterior third of pronotum (Fig. 35G); mesometaventral stria forming narrower arch; ground punctation of body conspicuous; prosternal carinal striae free posteriorly	Operclipygus minutus sp. n.
12	Lateral submarginal pronotal stria present as a short fragment in distinctly less than anterior half	13
–	Lateral pronotal stria longer, complete or posteriorly abbreviated behind midpoint	18
13	Dorsal elytral stria 4 complete, almost reaching anterior margin of elytron	14
–	Dorsal elytral stria 4 not extending anterad middle third of elytron	Operclipygus colombicus sp. n.
14	Frontal stria finely carinate, complete across middle, dividing separately concave epistoma and frons; upper surface of antennal club with round, basolateral sensory depression (Fig. 4I); lateral metaventral stria bent laterad at apex toward metepisternum	Operclipygus confertus sp. n.
–	Frontal stria not carinate, depression of frons and epistoma confluent; other characters varied15
15	Body very small, <1.5 mm; ground punctation of pronotum and elytra fine but relatively conspicuous (Fig. 35C); pygidium short, basal width distinctly greater than midline length (Fig. 35D)	Operclipygus prominens sp. n.
–	Body larger, >2 mm; body smoother, ground punctation of pronotum and elytra relatively inconspicuous; pygidium longer, midline length greater than basal width	16
16	Antennal bossae prominent, frontal stria slightly displaced dorsad, nearly straight across front (Fig. 35A); epistoma broadly concave; prosternal carinal striae free posteriorly; pygidium with numerous, conspicuous larger punctures over dense ground punctation (Fig. 35B)	Operclipygus callifrons sp. n.
–	Antennal bossae not prominent, frontal stria sinuate at sides; epistoma very shallowly concave; prosternal carinal striae united posteriorly; pygidium with secondary punctures finer	17
17	Secondary pygidial punctures fine (Fig. 37D); T8 of male genitalia not strongly sclerotized, with deep, narrow basal emargination (Fig. 38E); W Amazonia	Operclipygus communis sp. n.
–	Secondary pygidial punctures slightly coarser (Fig. 37F); T8 of male genitalia strongly sclerotized, with shallower basal emargination (Fig. 38F); E Amazonia…	Operclipygus belemensis sp. n.
18	Pronotum with few or no coarse lateral punctures (Fig. 35E)	Operclipygus tiputinus sp. n.
–	Pronotum with numerous coarse lateral punctures	19
19	Recurved ends of median portion of anterior pronotal stria short, restricted to anterior fourth of pronotal length	20
–	Recurved ends of median portion of anterior pronotal stria long, reaching middle third of pronotal length	28
20	Pronotal prescutellar impression long, flame-shaped (Figs 34C, E)	21
–	Pronotal prescutellar impression represented by thin, striiform impression, approximately as long as scutellum	24
21	Prosternal carinal striae extending forward nearly to presternal suture, prosternal keel not narrowed anterad; Central America	22
–	Prosternal carinal striae united well posterad presternal suture, keel distinctly narrowed anterad (Fig. 42D); Amazonia	23
22	Pronotum with <20 coarse lateral punctures (Fig. 42H); propygidial punctures small, ocellate, separated by nearly their diameters	Operclipygus praecinctus sp. n.
–	Pronotum with entire lateral third of disk coarsely punctate (Fig. 42F); propygidial punctures denser, separated by about half their diameters	Operclipygus assimilis sp. n.
23	Lateral pronotal punctures numerous (>20) and coarse (Fig. 34E); body larger (~2.5 mm); only known from Bolivia	Operclipygus ignifer sp. n.
–	Lateral pronotal punctures fewer (<20) and rather shallow (Fig. 34C); body smaller (~2 mm); distribution poorly documented, probably only northeastern Amazonia	Operclipygus hospes (Lewis)
24	Lateral submarginal pronotal stria complete	25
–	Lateral submarginal pronotal stria slightly abbreviated posteriorly; frontal stria weakly carinate, dividing depressed epistoma and frons	Operclipygus confertus sp. n.
25	Posterior ends of prosternal carinal striae united; anterior half of epistoma convex	26
–	Posterior ends of prosternal carinal striae free; epistoma longitudinally concave throughout	27
26	Fourth dorsal stria complete (Fig. 45C)	Operclipygus curtistrius sp. n.
–	Fourth dorsal stria abbreviated (Fig. 41D)	Operclipygus novateutoniae sp. n.
27	Central portion of frontal stria detached from sides (Fig. 34G)	Operclipygus subterraneus sp. n.
–	Frontal stria complete, not interrupted at sides	Operclipygus tenuis sp. n.
28	Posterior ends of prosternal carinal striae united; secondary punctures on pygidium tiny and sparse (Fig. 37G)	Operclipygus innocuus sp. n.
–	Posterior ends of prosternal carinal free; secondary punctures on pygidium larger and dense	Operclipygus incisus sp. n.