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Holotype Male.“Venezuela: Mérida State; 8°52.423'N, 70°37.611'W, 1616m; Cascada Velo de la Novia; 24.i.2012; leg. Short, Arias, & Gustafson; logs and kicknetting; VZ12-0124-01B” Holotype deposited in MIZA. Paratypes (18):“VENEZUELA: Mérida State; 8°52.423'N, 71°37.611'W, 1616 m; Cascada Velo de la Novia; 19.vii.2009; leg. W. Shepard; gross sample; VZ09-0719-01Z” (4 specimens SEMC). “VENEZUELA: Mérida State; 8°51.933'N, 70°37.131'W, 1682m; ca. 12 km SE of Santo Domingo; leg. Short, Arias, & Gustafson; 22.i.2012; log and stick jams; in river; VZ12-0122-03B” (8 specimens SEMC). “VENEZUELA: Mérida State; 8°51.933'N, 71°37.131'W, 1682m; ca. 12 km SE Santo Domingo; 19.vii.2009; leg. W. Shepard; gross sample; VZ09-0719-02Z” (6 specimens SEMC). Paratypes will be deposited in: 2 in MIZA, 2 in MALUZ, 2 in USNM, 12 in SEMC.
This species can be distinguished from all other species of Pharceonus by its large size (3.5–4.1mm), dark brown color (Fig. 77), narrow genitalia (aedeagus + phallobase) (6x as long as wide) (Fig. 80), and pronotum with only a shallow bisinuate transverse impression across apical third (Fig. 77).
Holotype male. Body elongate, sub-parallel, moderately convex. Total length 3.3 mm, greatest width 1.3 mm. Cuticle dark brown, base of maxillary palpus, six basal antennomeres, femora, and tarsi testaceous (Fig. 78). Dorsal surface with dense, erect brownish hair-like setae and denser and finer, golden, recumbent setae (Fig. 77). Surface microreticulate, with dense fine punctures.
Head moderately coarsely, densely punctate; punctures separated by their diameter; cuticle microreticulate. Clypeus with anterior margin truncate. Fronto-clypeal suture deep and slightly curved. Labrum with anterior margin entire and straight; angle on each side rounded, covered with golden setae approximately twice as long as setae on head. Eyes protruding only slightly laterally; separated by a distance about three times the eye-width; bordered by long dark brown curved setae (“eyelashes”) that arise near dorsal and ventral sides of eyes and extend toward middle of eye, setae not as prominent as in other genera. Antenna 11 segmented, pubescent, slightly clubbed; basal two antennomeres with long, brown, hair-like setae, thicker in width than proceeding antennomeres, with dense recumbent setae and dense brushy light brown setae (Fig. 77). Antennal club of six antennomeres, compact, thickened towards apex. Antennae short, reaching transverse groove of pronotum. Apical five antennomeres dark brownish black, with dense recumbent setae. Apical antennomere rounded.
Pronotum heavily sculptured, wider than long (1.1 mm and 1.0 mm, respectively); widest at basal third; anterior width two thirds the posterior width; anterior margin strongly convex over base of head; base tri-sinuate (Fig. 77). Pronotum with a shallow sublateral depression on each side extending from a deep anterolateral fovea near the anterior margin towards the base, where it is joined to sub-basal, transverse and bisinuate shallow depression; a short medial longitudinal and superficial groove joins the sub-basal and transverse depression with a strong tranverse and bisinuate depression at apical third; surface similarly punctate to head (Fig. 77). Pronotal base with strong median gibbosity anterior to scutellum. Hypomeron oblique (Fig. 79). Scutellum flat, broader than long, elevated posteriorly; posterior angle obtuse. Prosternum long in front of procoxae; with tuft of long, golden setae apicomedially. Anterior margin reflexed ventrally. Prosternal process scutiform, broad at base and tapering to apex; disc slightly impressed, lateral margins reflexed; middle convex; apex acuminate (Fig. 78). Mesoventrite short, depressed, with a deep, narrow, V-shaped depression for reception of apex of prosternal process. Metaventrite with disc inflated on posterior three-fourths, finely punctate behind mesocoxae; with deep, impressed 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 (Fig. 78).
Elytra more than three times as long as pronotum; lateral margins slightly sinuate; humeri and base adjacent to scutellum strongly gibbous; lateral margins smooth; apex rounded (Fig. 79). Each elytron with 10 coarse striae formed by a row of deep punctures well separated by more than three times their diameter; striae slightly impressed becoming narrower and more shallow towards the apex; strial punctures coarse basally, becoming progressively finer towards apex; striae 3 and 4 converging sub-apically; intervals flat (Fig. 77). Elytral surface with dense, golden pubescence.
Legs thin and short. Pro-, meso- and metatibiae with very short fringe of tomentum extending from about mid-tibia to nearly the tip. Surface of legs entirely pubescent, including mesotibiae. Mesotibia with small glabrous patch basally. Apical tarsomere of all legs with glabrous patch dorsally.
Abdomen with five ventrites. First ventrite distinctly carinate adjacent to metacoxae; carinae extending longitudinally behind metacoxae for almost entire length of first ventrite; cuticle densely covered with short, recumbent setae (Fig. 78). Ventrite IV with median V-shaped carina; carina covered with thicker setae than rest of ventrite. Last ventrite subtruncate, covered with dense, long, dark brown setae. Genitalia (aedeagus + phallobase wide, 6x as long as wide, slightly curved (Fig. 80).
Female. Externally similar to male except slightly larger in size, elytral gibbosities more producted, and elytral sutural stria slightly inflated in apical third. Protibiae slightly less curved than those of male. Metaventral disc not as deeply and less concave. Abdominal ventrite IV lacking V-shaped carina. Apical abdominal ventrite with less dense setae than male.
This species varies slightly in color, from dark brown to medium brown, length (3.5–4.1 mm), and degree of setation.
The specific epithet “ariasi” is a patronym in honor of Mr. Quintin Arias, who helped to collect many of the specimens of this species.
Distribution and habitat
This species is limited to the type locality at Cascada Velo de la Novia and from a nearby stream 12 km southeast of Santo Domingo, in Mérida State, Venezuela (Fig. 8). The specimens were found clinging to waterlogged woody debris in the river.
No other laraine species were collected with Pharceonus ariasi.
- Maier, C; 2013: A revision of the Larainae (Coleoptera, Elmidae) of Venezuela, with description of nine new species ZooKeys, 329: 33-91. doi