Hexanchorus falconensis, 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 : 45-48

Hexanchorus falconensis sp. n. Figs 4, 28, 29, 30, 31

Type Material.

Holotype Male."Venezuela: Falcón State; 11°10.667'N, 69°33.695'W 563 m; Cataratas del Hueque; scrubbing flat rocks in flow; leg. A. Short; VZ09-0709-01A" Holotype Deposited in MIZA. Paratypes (9): VENEZUELA: Falcón State: Same locality data as holotype (7 specimens SEMC). "Venezuela: Falcón State; 11°10.667'N, 69°33.695'W 563 m; Cataratas del Hueque; Short & Gustafson; leafpacks/roots; at river margin; VZ09-0709-01B" (1 specimen SEMC). "Venezuela: Falcón State; 11°10.667'N, 69°33.695'W 563 m; Cataratas del Hueque; leg. Shepard; mud puddles/pools; gross sample; VZ09-0709-01Z" (1 specimen SEMC). Paratypes will be deposited in: 1 in MALUZ, 1 in USNM, 7 in SEMC.

Diagnosis.

Hexanchorus falconensis can be distinguished from all other species of Hexanchorus by the distinctive aedeagus, with a “can-opener” tooth at apex (Fig. 31), and the extremely elongated elytral apices of the female (Fig. 28). Additionally, the pronotum lacks a median longitudinal impression (Fig. 28).

Description.

Holotype Male. Body elongate, subparallel, dorsum moderately convex. Length, 4.5 mm; greatest width, 1.1 mm. Body dark brown dorsally; venter dark brownish black (Fig. 28). Base of antenna testaceous ventrally, base of femur, trochanter testaceous (Fig. 29). Dorsal surface densely covered with short recumbent setae; ventral surface densely covered with longer, golden, recumbent setae. Setae with greenish iridescence (Fig. 28). 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 square; lateral angles of clypeus with dense turt of golden setae. Labrum with anterior margin entire and broadly rounded; labrum expanded laterally, covered with setae approximately three times as long as setae on head; lateral margins of clypeus with thick brush of curly, golden 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, clubbed; basal antennomeres I and II testaceous ventrally, with dense recumbent setae and long, dark brown setae (Fig. 29). Antennae serrate, thickening slightly towards apex (Fig. 28). Antennae long, reaching past transverse groove of pronotum. Apical antennomeres dark brownish black, with dense recumbent setae. Apical antennomere pointed (Fig. 29).

Pronotum 1.0 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 obtuse, 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. 28). Pronotal disc lacking median longitudinal depression, with slight postero-medial impression; disc covered with short, dense, iridescent setae (Fig. 28). Lateral projection of hypomeron reduced, nearly absent. Prosternum short in front of procoxae; lacking tuft of setae apicomedially (Fig. 29). Prosternal process broadly triangular, broad at base and slightly tapering to apex; disc slightly impressed, without V-shaped groove; lateral margins reflexed; middle concave; apex broadly acuminate (Fig. 29). Scutellum slightly longer than broad, strongly convex, distinctly elevated above the adjacent elytral intervals. 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. 29). Procoxae and metacoxae moderately widely separated; mesocoxae slightly more widely separated (Fig. 29). Protibia lacking excavation for reception of tarsi, lacking apical tooth. Protarsus of male strongly expanded apicomedially. Mesotibiae of male with medial pubescent area long; lateral pubescent area only at extreme base; with fine, short, nearly longitudinal carina on inner apex. Tarsal claws long and stout, light brown. Metafemur of male with small 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, iridescent pubescence; humeral area swollen (Fig. 28). Elytral striae obscured apically. Elytron widening to about posterior two-thirds before converging to rounded and acute apex. Apical third of elytron not, or just barely inflated. Elytron without strong impression at basal third. Lateral bead of elytron sinuate. 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. 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 deeply and broadly emarginate. Aedeagus distinctive, with two small notches at tip ( “can-opener” apex), parameres reaching more than halfway up length of aedeagus.

Female. Externally similar to male except elytral apices strongly acuminate and extended posteriorly (Fig. 28). Protibiae 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 (4.0-4.3 mm), and degree of setation.

Etymology.

This species is named “falconensis” in reference to the type locality in Falcón State, Venezuela.

Habitat and distribution.

Hexanchorus falconensis is only known from Cataratas del Hueque in Falcón State, Venezuela (Fig. 4). Specimens were collected in leaf packs and at stream margins, as well as in bulk samples and by scubbing rocks in the flowing water on flat, waterslide-like rocks.

Associated species.

This species was collected in association with Phanocerus congener . Other water beetles collected in the same habitat include: Lutrochus vestitus ( Lutrochidae ) (Maier & Short, 2013), Heterelmis spp., Microcylloepus spp., and Onychelmis spp. ( Elmidae : Elminae ), and the larvae of Psephenidae .