A full description of the New World species of Hymenorus is not possible at this time pending modern revisions of the more than 170 North and Central American species of the genus. However, the following brief description will readily distinguish these three species from all other New World species of Hymenorus.

Body narrowly elongate-oval (Fig. 1); length 7.5–10.0 mm. Eyes large, moderately separated dorsally; OI of males varying from 18 to 27, females slightly more widely separated, OI varying from 18–33. Antennae narrowly elongate, antennomeres four through ten narrowly elongate, approximately two times longer than wide. Pronotum (Fig. 2) wider than long, width at base slightly narrower than width of base of elytra; PI ranging from 62 to 78; disc with fine, dense microsculpture between punctures; punctures coarse, dense, narrowly separated, evenly distributed over disc; each puncture obliquely impressed. Metaventrite moderately densely punctate medially, punctures becoming sparser laterally; without median patches of dense, elongate setae. Like all Hymenorus species, the third and fourth segments of the pro- and mesotarsi and the penultimate segment of the metatarsi have a distinct membranous lobe on the ventral margins.

Male. Hymenorus excavatus and Hymenorus bifurcatus have the second segment of the anterior tarsus with a small, rudimentary lobe and a densely pubescent pad on the venter of the basal segment; only the third and fourth segments of the protarsi are lobed in Hymenorus balli. The anterior tarsal claws of the three species each have at least 20 teeth (Fig. 3). The fifth abdominal ventrite is highly modified, in one species (Hymenorus excavatus) (Figs 10, 11), the ventrite is deeply, triangularly excavate from the apical margin to the anterior third; in Hymenorus balli (Figs 4–5) and Hymenorus bifurcatus (Figs 7–8) the ventrites have a distinct, bifurcate process projecting ventrally from the middle of the disc. Lobes of eighth sternite of each species are highly modified (Figs 19–21), unlike any other species of the genus.

Female. The ninth tergite (Figs 6, 9, 12) of each species is highly modified and completely unlike any other known species of the genus. In most species of the genus the apical margin of the tergite is evenly convex and the length of the tergite varies from short to elongate.

I have not provided a key to distinguish these species. Other than sexual characters they are very similar. The modifications of the male fifth abdominal ventrite and lobes of the eighth sternite and the shape of the female ninth tergite will readily distinguish the species. In most series a few of the sexual characters are readily visible without dissections.

Body light to dark brown; legs light brown to testaceous; narrowly elongate-oval (Fig. 1). Length 7.5–10.0 mm. Setae short, subrecumbent; uniformly reddish-brown. Eyes moderately separated dorsally (OI of male 19–25 and of female 25–33). Vertex coarsely, densely, punctate; punctures separated by distance approximately half diameter of a puncture. Antennae narrowly elongate, antennomeres 3–11 slightly and evenly widened from base to apex. Apex of sixth antennomere extending posteriad to base of pronotum; antennomeres 3 and 4 subequal in length; tenth antennomere approximately two times longer than wide.

Pronotum distinctly wider than long, PI index 62–71; sides evenly, gradually narrowed from base to apical fourth then evenly curved to continuously curved apical margin; basal angles rectangular; base slightly, but distinctly narrower than base of elytra; basal margin slightly bisinuate; basal foveae small, shallowly impressed, separated by broad, shallow, median impression; midline unimpressed; sides at basal angles slightly reflexed. Disc with fine, dense microsculpture between punctures; punctures coarse, dense, narrowly separated, evenly distributed over disc; each puncture obliquely impressed.

Hypomeron finely, densely, evenly punctate to lateral margins. Basal three abdominal ventrites moderately densely, evenly punctate; punctures each with a short, recumbent seta. Elytra with striae evenly, shallowly impressed; strial punctures circular, almost contiguous along striae; strial interstices slightly convex; interstices moderately densely punctate; punctures randomly distributed, approximately 2 or 3 punctures wide across interval. Metatarsus with basal segment subequal in length to segments 2–4 combined.

Male. Second segment of anterior tarsus without rudimentary lobe on ventral margin. Tibiae not modified. Posterior femora with ventral margin flattened, glabrous, with outer margin of glabrous area distinctly carinate. Anterior tarsal claws each with more than 20 teeth. Metaventrite finely, densely punctate medially; punctures becoming coarser, sparser laterally; median punctures each bearing an elongate, posteriorly directed seta. Fifth abdominal ventrite highly modified (see Figs 4, 5) with large, broad, bifurcate process projecting ventrally from middle of disc; bifurcate process densely setate on outer margins; disc broadly, moderately deeply impressed behind bifurcate process; apical margin of ventrite broadly truncate. Lobes of eighth sternite (Fig. 19) highly modified; narrowed medially with apex broadly widened, inner anterior angle of apical enlargement triangularly narrowed; base of lobes with a moderately long, less heavily sclerotized lobe projecting medially. Lobes of ninth sternite (Fig. 19) short, strongly curved medially, apex broadly rounded. Apicale (Figs 15–16) moderately broad with sides slightly narrowed from base to broadly truncate apex; penis narrowly elongate with sides evenly narrowed from base to apex.

Female. Anterior tarsus without rudimentary lobes or setaceous pads on basal two segments. Anterior tarsal claws each with 9–10 teeth. Metaventrite moderately coarsely punctate medially; punctures becoming slightly coarser, sparser laterally; median punctures each bearing a short, appressed seta. Apical portion of fifth ventrite broadly impressed. Ninth tergite (Fig. 6) with apical margin broadly, evenly convex; with narrow, evenly sclerotized band completely around sides and apex of tergite.

Holotype, male, with labels as follows: “GUAT, 22 km S San Marcos, 5000’, IX-3–1965, JM.Campbell/ HOLOTYPE ♂ Hymenorus balli, desig. 2013, JM Campbell”. The holotype is deposited in the CNCI.

Paratypes. Males 12, females 19.

GUATEMALA: Sacatepequez: Finca Florencia, 24.VI.1993, JMC (CNCI) 1. Quezaltenango: nr. tunnel, 2 km N Santa María, 5500 ft, VII.10.1965, X.24.1965 JMC (JMCC) 3; 3 km N Santa María, 6000 ft, VIII.27.1965, JMC (JMCC) 1. San Marcos: 20 km S San Marcos, 4500 ft, IX.4.1964, JMC (CNCI) 2; 22 km S San Marcos, 5000 ft, IX.3.1965, X.2.1965, JMC (CNCI) 8.

MEXICO: Chiapas: Pico Gallo, NW Union Juarez, 5000–6000 ft, 1972, G. E. Ball (CNCI, JMCC) 16.

This species is named in honor of George Ball, University of Alberta, Edmonton in recognition of his many contributions to the study of Coleoptera (particularly Carabidae). Dr. Ball collected a long series of this species from Chiapas, the only record of any of the three species described in this paper from Mexico.

The modifications of the male fifth ventrite (Figs 4, 5) are the most unusual of any species of Alleculinae known to me from the New World. In addition to the bizarre modifications of the fifth ventrite, the shape of the male lobes of the eighth and ninth sternites (Fig. 19) and the shape of the apicale (Figs 13, 14) of the aedeagus will readily distinguish the species. The lobe attached to the base of the inner side of each lobe of the eighth sternite is unknown from any other species of the genus. Females are easily distinguished by examination of the eighth tergite (compare Figs 6, 9, 12).

This species was collected by beating arboreal bromeliads and from under moss and bromeliads on tree trunks.

This species is almost indistinguishable from Hymenorus balli and Hymenorus excavatus based on non-sexual characters. Only the slight variations in non-sexual characters are described below; full descriptions are given for the male and female characters.

Length 7.9–8.8 mm. Eyes moderately separated dorsally; OI 23 to 27 and of female 28 to 31. PI 72 to 78; basal fovea of pronotum slightly more elongate than in Hymenorus balli and Hymenorus excavatus, extending from base to near middle of disc. Pronotal punctures angularly impressed throughout.

Metatarsus with basal segment subequal to or slightly longer than segments 2–4 combined.

Male. Anterior tarsus with rudimentary lobe on venter of second segment and pubescent pad on venter of first segment. Posterior femora evenly convex on ventral margin; without carina on outer side of ventral margin. Anterior tarsal claws each with more than 20 teeth (Fig. 3). Fifth ventrite highly modified (see Figs 7, 8), with small, evenly curved process projecting ventrally from middle of disc; apex of process shallowly bifurcate; disc broadly, shallowly impressed behind median process; apical margin broadly convex. Lobes of eighth sternite (Fig. 20) broad, strongly sinuate and curved medially; apex of lobes narrowly rounded; inner sides of lobes broadly, deeply, concavely impressed. Lobes of ninth sternite (Fig. 20) short, narrow, with apical margin moderately narrowly rounded. Apicale (Figs 15, 16) triangular with sides evenly narrowed from base to narrowly rounded apex; penis as in Hymenorus balli.

Female. Anterior tarsal claws each with 7–10 teeth. Apical portion of fifth abdominal ventrite narrowly impressed. Ninth tergite (Fig. 9) broad, almost arrowhead shaped with sides widened from truncate apical margin, then abruptly narrowed to base.

Holotype, male, with labels as follows: GUAT, Border of depts. of Sololá and Chimaltenango, nr. Los Robles, IX-12–1965, 6000’, JM Campbell/ HOLOTYPE, ♂ Hymenorus bifurcatus, desig. 2013, JM.Campbell The specimen is deposited in the CNCI.

Paratypes. Males 16, females, 17.

GUATEMALA: Quezaltenango: Tzanjoyan, 3 km SE Zunil, 2300 m, XI.1.1965, JMC (CNCI, JMCC) 5. Sacatepéquez: Finca Florencia, 24.VI.1993, JMC (JMCC) 2. San Marcos: 20 km S San Marcos, 4500 ft, IX.4.1964, JMC (JMCC) 1; 22 km S San Marcos, IX.3.1965, JMC (JMCC) 1. Border between Sololá and Chimaltenango: nr. Los Robles, IX.12.1965, 6000 ft, JMC (CNCI, JMCC) 27.

This species is named bifurcatus in recognition of the small, bifurcate process near the middle of the male fifth ventrite.

This species is almost identical to the sympatric species Hymenorus balli in all external characters except for the lack of a carina on the venter of the posterior femora of the males. The process on the male fifth visible ventrite (Figs 7–8) is somewhat similar to that of Hymenorus balli except that it is much smaller and the apical margin of the bifurcate lobes are narrow and shallowly impressed. The lobes of the male eighth sternite (Fig. 20) are very different from those of Hymenorus balli; each lobe is broad, spoon-shaped with the apical margin narrowly convex. The deep, concave impression on the inner side of each lobe is unique within the genus. Females may be distinguished by the very different shape of the ninth tergite (compare Figs 6, 9, and 12).

This species was collected by beating dead leaves of recently cut trees, by beating composit shrubs, and from an arboreal bromeliad.

This species is almost indistinguishable from Hymenorus balli and Hymenorus bifurcatus based on non-sexual characters. Only the slight variations in non-sexual characters are described below; full descriptions are given for the male and female characters.

Length 8.0–9.7 mm. Eyes moderately separated (OI of male 18 to 24 and of female 18 to 28).

PI index 66 to 73; sides narrowed from base to apical fourth then evenly curved to slightly concave to truncate anterior margin; median basal fovea more elongate than in Hymenorus balli, extending from base to near middle of disc.

Elytra with punctures of intervals slightly denser than in Hymenorus balli and Hymenorus bifurcatus with 3 or 4 punctures across each interval. Metatarsus with basal segment distinctly longer than segments 2–4 combined.

Male: Venter of anterior tarsi with rudimentary lobes on apex of second segment and densely pubescent pad on basal segment. Posterior femora evenly convex on ventral margin, without carina on outer side. Anterior tarsal claws each with more than 20 teeth. Fifth abdominal ventrite highly modified (Figs 11, 12), broadly, deeply, triangularly impressed from apical margin to basal third; sides of impression sharply carinate. Lobes of eighth sternite (Fig. 21) broadly spoon-shaped, curved medially; outer sides evenly convex, apex of lobes narrowly triangular; inner side of lobes each with short tooth near base. Lobes of ninth sternite (Fig. 21) very short, not extending beyond base of lobes of eighth sternite. Apicale (Figs 17, 18) broad, with sides slightly concave medially; apex truncate; penis narrowly triangular.

Female: Anterior tarsal claws each with 7–10 teeth. Apical third of fifth abdominal ventrite broadly, shallowly, concavely impressed; apical margin broadly convex. Ninth tergite (Fig. 12) with apical margin broadly convex; laterally, slightly truncate medially; heavily sclerotized area covering all of tergite except small, triangular, membranous section medially at base.

Holotype, male, with labels as follows: 22 km S San Marcos, 5000’, IX-3–1965, JM Campbell/ HOLOTYPE ♂, Hymenorus excavatus, desig. 2013, JM.Campbell The specimen is deposited in the CNCI.

Paratypes: 13 males, 11 females.

GUATEMALA: Esquintla: 3 km E San Vicente Pacayá, 5500 ft, V.14.1966, JMC (JMCC) 2. San Marcos: 10 km N La Reforma, 4500 ft, IX.4.1964, JMC (CNCI, JMCC) 7; 22 km S San Marcos, 5000 ft, VI.4.1966, X.2.1965, IX.3.1965, JMC (CNCI, JMCC) 11; 20 km S San Marcos, 4500 ft, IX.4.1964, JMC (JMCC) 2. Suchitepéquez: UVG Reserve, S side of Volcán Atitlán, 91°8.85W, 14°32.04N, X.9–11.2009, 1543 m, (WBWC) 2.

This species is named excavatus in recognition of the deeply excavate fifth visible male ventrite.

Hymenorus excavatus is similar in external appearance to the two preceding species. Males may be readily identified by the unique sexual modifications of the male fifth abdominal ventrite (Figs 10–11), the eighth and ninth sternites (Fig. 21) and the aedeagus (Figs 17–18). Females are difficult to distinguish externally, but can easily be distinguished by the unique shape (somewhat like an arrowhead) of the ninth tergite (compare Figs 6, 9, and 12). Females can be provisionally distinguished from those of Hymenorus balli by the shallower and broader impression of the fifth abdomnal ventrite.