Hexanchorus dentitibialis, Maier, Crystal A., 2013

Maier, Crystal A., 2013, A revision of the Larainae (Coleoptera, Elmidae) of Venezuela, with description of nine new species, ZooKeys 329, pp. 33-91 : 42-45

Hexanchorus dentitibialis sp. n. Figs 3, 23, 24, 25, 26, 27

Type material.

Holotype Male."Guayabita Cr.; Turmero: AR [Aragua State]; Venezuela; 466m 21-I-71; J. Salcedo; colr." Holotype deposited in MIZA. Paratypes (2): Same locality data as holotype. Paratypes will be deposited in: 1 in SEMC, 1 in MIZA.

Diagnosis.

This species most closely resembles Hexanchorus mcdiarmidi , but can be distinguished from that species by the presence of a deep posteromedian impression on the pronotum (Fig. 27) and the extended elytral apices on the male (Fig. 23), which Hexanchorus mcdiarmidi lacks. Additionally, species identity can be confirmed by the distinctive aedeagus, which is truncate in lateral view (Fig. 26). This character does not occur in any other Hexanchorus species.

Description. Holotype Male. Body elongate, subparallel, dorsum moderately convex (Fig. 23). Length, 3.1 mm; greatest width, 0.9 mm. Body dark brown dorsally; venter dark brownish black. Base of antenna testaceous ventrally, and base of femur trochanter testaceous (Fig. 24). Dorsal surface densely covered with short recumbent setae; ventral surface densely covered with slightly longer, golden, recumbent setae (Fig. 23). Setae lacking greenish iridescence. Surface microreticulate, with dense fine punctures; fine punctures separated by distance equal to puncture diameter.

Head moderately coarsely, densely punctate; punctures separated by their diameter; cuticle microreticulate. Clypeus with anterior margin straight; angle on each side acute; lateral angles of clypeus with dense tuft of golden setae. Labrum with anterior margin entire and broadly rounded, covered with setae approximately twice as long as setae on head; lateral margins of clypeus with thick brush of curly, dark brown setae. Eyes hemispherical, narrowed posteriorly and bordered by long black curved setae ( “eyelashes”) that arise near dorsal and ventral sides of eyes and extend toward middle of eye. Antenna pubescent, filiform; basal antennomeres I and II testaceous ventrally, with dense recumbent setae and long, dark brown setae (Fig. 23). Antennae without club, but thickening slightly towards apex. Antennae long, reaching past transverse groove of pronotum (Fig. 23). Apical antennomeres dark brownish black, with dense recumbent setae. Apical antennomere square.

Pronotum 0.8 mm long, 0.9 mm wide; with strong sublateral groove; lateral margins slightly sinuate; anterolateral angles square, not explanate; base of pronotum slightly sinuate and with broad lobe medially; posterolateral angles square, slightly explanate, declivous, depressed adjacent to each angle; discal area with fine, dense punctures, punctures separated by a distance equal to or less than their diameter; cuticle microreticulate (Fig. 27). Pronotal disc lacking median longitudinal depression, with slight postero-medial impression; disc covered with short, dense, recumbent setae (Fig. 27). Lateral projection of hypomeron truncate. Prosternum short in front of procoxae; lacking tuft of setae apicomedially. Prosternal process triangular, broad at base and tapering to apex; disc slightly impressed, with V-shaped groove; lateral margins reflexed; middle concave; apex acute (Fig. 24). Scutellum slightly longer than broad, flat, not distinctly elevated above the adjacent elytral intervals (Fig. 23). Mesoventrite short, depressed, with a deep, broad, V-shaped depression for reception of apex of prosternal process. Metaventrite with disc inflated on posterior three-fourths, finely punctate behind mesocoxae, punctures becoming more sparse laterally, with large, rounded depressions scattered on disc; with deep longitudinal groove on midline of disc, groove deepest and broadest on posterior third of disc; with short, dense pubescence; cuticular surface of metaventrite finely microreticulate.

Legs long and slender, dark brown (Fig. 24). Procoxae and metacoxae moderately widely separated; mesocoxae slightly more widely separated (Fig. 24). Protibia with deep excavation for reception of tarsi, with apical tooth (as in Fig. 46). Protarsus of male not expanded apicomedially (Fig. 24). Mesotibiae of male with medial pubescent area very long; lateral pubescent area only at extreme base (Fig. 23); with fine, short, nearly longitudinal carina on inner apex. Tarsal claws long and stout, light brown. Metafemur of male lacking internal glabrous patch.

Elytron with ten rows of fine punctures; punctures separated by a distance three to four times the diameter of the puncture; intervals with short, dense, recumbent pubescence and sparse erect setae; humeral area swollen (Fig. 23). Elytral striae visible apically. Elytron widening to about posterior two-thirds before converging to rounded apex. Apical third of elytron not inflated. Elytron without strong impression at basal third. Lateral bead of elytron slightly sinuate (Fig. 25). Elytra three times as long as pronotum; broadest point across humeri. Inner side of apex rounded; lateral margins smooth; humeri gibbous; elytral intervals slightly elevated; punctures on intervals no larger than finest punctures of head and pronotum and separated by 2-5 times puncture diameter.

Abdomen with five ventrites (Fig. 24). First three ventrites broadly, deeply depressed and distinctly carinate adjacent to metacoxae; carinae extending longitudinally behind metacoxae for almost entire length of first ventrite; cuticle densely covered with short, recumbent setae. Last ventrite shallowly and broadly emarginate (Fig. 24). Aedeagus wide, with truncate tip in lateral aspect, parameres reaching a little more than halfway up length of aedeagus (Fig. 26).

Female. Externally similar to male except elytral apices strongly pointed and slightly upturned (Fig. 23). Protibiae are slightly less curved than those of male. Mesotibiae without carina on inner apex. Metaventral disc not as deeply and less extensively concave. Abdominal sterna 1-3 convex, not concave.

Intraspecific variation.

This species varies slightly in color, length (3.1-3.3 mm), and degree of setation.

Etymology.

This species is named “dentitibialis”, meaning "toothed tibia" to describe the protibia, which has an excavation for reception of the tarsus and an apical tooth.

Distribution and habitat.

This species is only known from the type locality at Guayabita Creek, near Turmero, Aragua State, Venezuela (Fig. 3). The exact microhabitat is unknown.

Associated species.

No other Larainae species were collected with Hexanchorus dentitibialis .