Lutrochus acuminatus Grouvelle, 1889

Maier, Crystal A. & Short, Andrew E. Z., 2013, A revision of the Lutrochidae (Coleoptera) of Venezuela, with description of six new species, Zootaxa 3637 (3), pp. 285-307 : 286-289

Lutrochus acuminatus Grouvelle, 1889

( Figs. 1 , 4 , 8–13 )

Lutrochus acuminatus Grouvelle, 1889: 163

Type Material. Lutrochus acuminatus: Four syntypes in NMHN. Lectotype (here designated): [Point mounted. Point with “3”] “Colonia Tovar/E. Simon 1.11.88 ” “ Type ” “[yellow label] LECTOTYPE; Lutrochus acuminatus ; Grouvelle 1889; des. Maier & Short 2012”. Paralectotypes (3, here designated): [Point mounted. Point with “Ƥ”] “Colonia Tovar/E. Simon 1.11.88 ” “ Type ”. [2 specimens Card mounted] “Colonia Tovar/E. Simon 1.11.88 ” “ Type ” “[blue label] PARALECTOTYPE; Lutrochus acuminatus ; Grouvelle 1889; des. Maier & Short 2012”.

Other Material Examined (29). VENEZUELA: Aragua State: “ VENEZUELA:Aragua State/ 10.35669° N, 67.60645° W / Henri Pittier N.P.: Rio Castaño/ Regresiva del Diablo/ 6.i.2009; leg. A.E.Z. Short/ VZ09-0106-01A; log in stream” (7 specimens, SEMC). “ VENEZUELA:Aragua State/ 10.35669° N, 67.60645° W / Henri Pittier N.P.: Rio Castaño/ Regresiva del Diablo; 6.i.2009 / leg. Short, Miller, Camacho, Garcia/ VZ09-0106- 01X ” (9 specimens, SEMC, MALUZ). “ VENEZUELA:Aragua State/ P.N. Henri Pittier: Rancho Grande/ Stream & seep at Toma; 10.i.2006 / AS-06-021; leg. A.E.Z. Short” (14 specimens, SEMC, MIZA). “ VENEZUELA:Aragua State/ 10.35669° N, 67.60645° W / Henri Pittier N.P.: Rio Castaño/ Regresiva del Diablo; 6.i.2009 / leg. Short, Miller, Camacho, Garcia/ VZ09-0106- 01X ” (9 specimens, SEMC). “ VENEZUELA: Aragua State/ 10.37068° N, 67.59683° W, 1039m / H. Pittier N.P.: road to Choroni/ 6.i.2009; leg. Short, Miller,Camacho/ Garcia; VZ09-0106- 02X: stream” (4 specimens, SEMC). Trujillo State: “ VENEZUELA:Trujillo State/9° 19.371ʹN, 70° 9.303ʹW, 1770m / ca. 3 km NE Laguna Agua Negro/ leg. Short, Garcia, & Camacho/ 21.i.2009; VZ09-0121- 03X: small/ mountain stream w/ debris” (9 specimens, SEMC, MIZA).

Diagnosis. This species can be distinguished from others by the explanate elytra, with the epipleuron appearing broad in ventral aspect ( Figs. 9, 10 ); its reddish-brown color; the strongly deflexed prosternum ventrally in anterior half ( Fig. 12 ); and the strongly triangular apical maxillary palpomere ( Fig. 11 ).

Redescription. LECTOTYPE MALE.—Length 3.0 mm; width 1.7 mm. Body ovate and strongly convex, reddish brown to medium brown, densely pubescent; clothed with two types of short, fine, golden hairs ( Figs. 8, 9 ). Dorsal setae erect and long, mixed with dense, recumbent short setae. Short recumbent setae on pronotum facing anteriorly, short recumbent setae on elytra facing posteriorly, giving pronotum golden appearance in dorsal aspect ( Fig. 8 ).

Head broad, broadly rounded, weakly grooved beneath eye for reception of antenna ( Fig. 11 ). Eye rounded, small, with short, golden interfacetal setae; eyes smooth within outline of head. Antenna short, reaching slightly past anterior border of pronotum, apical 9 antennomeres short, clavate, medium brown and testaceous at apex, clothed with short, recumbent golden setae. Frontoclypeal suture indistinct. Clypeal margin straight, with brush of long setae apically, setae not reaching apex of labrum. Apical margin of labrum sinuate, with apical setal brush, lateral setae three times as long as medial setae. Labrum clothed with dense, golden setae. Mandibles large, dark brown, sickle-shaped; apex of mandible with three short teeth. Maxilla with 4-segmented palpus, apical palpomere flattened and triangular, almost two times as wide as long, abruptly truncate at apex ( Fig. 11 ). Labial palpus 3- segmented; apical palpomere cylindrical.

Pronotum pubescent, reddish-brown, two times as wide as long at base, bisinuate at base. Lateral edge of pronotum with distinct bead ( Fig. 8 ). Posterior margin anterior to scutellum straight to slightly curved, without notch. Disc of pronotum broadly convex. Scutellum triangular, a little wider than long. Hypomeron excavate posteriorly to accommodate femur.

Elytron pubsecent, reddish-brown, widest at midlength. Elytron broadly convex, with dense, small punctures, lacking puncture striae; humerus not protuberant ( Fig. 8 ). Lateral edge with distinct bead ( Fig. 10 ), epipleuron expanded, broad in ventral aspect ( Fig. 9 ). Elytral apex rounded ( Fig. 8 ).

Prosternum transverse, approximately 1.5 times as wide as long; strongly deflexed to accommodate withdrawn head, with strong transverse fold anteriorly; anterior edge with strong bead ( Fig. 12 ). Prosternal process about 1.2 times as wide as long, lacking bead laterally, acuminate posteriorly ( Fig. 12 ). Mesoventrite pubescent, lacking glabrous patch ( Fig. 9 ). Mesepisternum and mesepimeron excavated to accommodate folded front and middle legs. Mesepimeron extended posteriorly roughly halfway to metacoxae.

Legs short. Profemur and protibia densely pubescent. Protibia pubescent. Protarsus with apical four tarsomeres glabrous, except for tufts of golden setae ventrally on all tarsomeres; apical tarsomere 0.7 times as long as preceding four tarsomeres combined. Mesocoxa pubescent, lacking tuft of long golden setae basally. Mesofemur densely pubescent. Mesotibia completely glabrous, with few scattered setae, lacking small patch of golden setae at apex; apex with excavation laterally for reception of tarsus. Mesotarsus with all tarsomeres glabrous, except for tufts of golden setae ventrally on all tarsomeres, lacking single long seta arising from fourth tarsomere; apical tarsomere 0.8 times as long as preceding four tarsomeres combined. Metatrochanter globose, with single short hook-like posterior extension basally ( Fig. 9 ). Metafemur densely pubescent. Metatibia pubescent for entire length. Metatarsus glabrous, with apical tarsomere 0.7 times as long as previous four combined.

Abdomen densely pubescent, with five ventrites. First ventrite shallowly excavated for reception of folded hind legs ( Fig. 9 ). Apical ventrite broadly rounded.

Genitalia as illustrated, basal piece + parameres 1.9 mm long. Aedeagus slender and curved evenly to apex. Parameres fused, pointed, with extended apex in lateral aspect ( Fig. 13 ).

Female. Length 4.0 mm; width 2.0 mm. Externally similar to male, females generally larger than males.

Intraspecific Variation. This species varies considerably in size, ranging from 3.0– 4.3 mm long and 1.7–2.3 mm wide. Additionally, specimens vary slightly in color – from light reddish-brown to dark reddish-brown, specimens also have differing levels of setation, with patches where setae have rubbed off, as well as patches where setae have become matted down with grease.

Habitat and Distribution. All newly collected specimens were found in small (<2 m wide), densely forested mountain streams at elevations over 1000 m. Most specimens were collected directly from submerged logs and woody debris ( Fig. 1 ). The type locality collection and most additional collections were made in the Coastal Mountains of north-central Venezuela. One additional collection was taken in the adjacent northeastern extent of the Merida Andes ( Fig. 4 ).

Remarks. This species was previously the only named species in the family from Venezuela. This species is distinctive, not resembling any others found in Venezuela.

Figures

FIGURE 1. Habitat of Lutrochus acuminatus: Venezuela, Aragua State, Rio Castaño (collecting event VZ 09 - 0106 - 01 A). A) Arrow indicates a previously submerged log on which specimens were found (B).

FIGURES 4 – 7. 4. Map of Venezuela showing collection localities of L. acuminatus (red circles) and L. cauraensis (yellow square). 5. Map of Venezuela showing collection localities of L. vestitus (red circles). 6. Map of Venezuela showing collection localities of L. meridaensis (red circles), L. minutus (orange circles), and L. maldonadoi (yellow circles). 7. Map of Venezuela showing collection localities of L. violaceus (red circles) and L. gustafsoni (yellow circles).

FIGURES 8 – 13. Lutrochus acuminatus Grouvelle: 8. Habitus, dorsal view; 9. Habitus, ventral view; 10. Habitus, lateral view; 11. Head, three-quarters view, showing shape of apical maxillary palpomere; 12. Prosternum, ventral view; 13. Aedeagus, dorsal and lateral views (scale bar = 0.62 mm).