Lutrochus gustafsoni, Maier, Crystal A. & Short, Andrew E. Z., 2013

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 : 291-293

Lutrochus gustafsoni n. sp.

( Figs. 7 , 20–26 )

Type Material. Holotype male: “ Venezuela Exp./Culebra N. Duida/ Territ. Amazonas/ April 7-16 1950 ” “J. Maldonado/ Capriles Coll.” “USNM00768075” Holotype deposited in MIZA. Paratypes (2): VENEZUELA: Amazonas State: “ Venezuela Exp./Territ. Amazonas/ Upper Cunucunuma/ Julian Apr. 28, 1950 ” “J. Maldonado/ Capriles Coll.” (2 specimens, USNM, SEMC).

Diagnosis. This species can be distinguished from all other described Lutrochidae by its large size (~5.0 mm), short antennae, which barely reach the anterior margin of the pronotum, and the entirely glabrous apical protarsomere, which is least 1.5 times as long as previous four combined ( Fig. 23 ).

Description. MALE.- Length 5.0 mm; width 2.9 mm. Body wedge-shaped and strongly convex, dark brown to black, densely pubescent; clothed with distinctly short, fine, slightly recumbent golden hairs ( Fig. 20 ).

Head broad, broadly rounded. Eye rounded, small, with short, golden interfacetal setae; eyes smooth within outline of head. Antenna very short, reaching only the anterior border of pronotum, antennomeres dark brown and clavate, clothed with short golden setae. Frontoclypeal suture indistinct. Clypeal margin straight, with brush of long setae apically, setae nearly as long as labrum. Apical margin of labrum sinuate, with short apical setal brush. Labrum clothed with sparse, golden setae. Mandibles large, dark brown, sickle-shaped; apex of manidible blunt, lacking distinct teeth. Maxilla with 4-segmented palpus, apical palpomere flattened and triangular, truncate at apex. Labial palpus 3-segmented; apical palpomere fusiform.

Pronotum pubescent, dark brown, two times as wide as long at base, bisinuate at base ( Fig. 20 ). Lateral edge of pronotum with distinct bead, broadly rounded. Posterior margin straight anterior to scutellum. Disc of pronotum broadly convex. Scutellum triangular, as wide as long; clothed in recumbent golden setae. Hypomeron excavate posteriorly to accommodate profemur.

Elytron pubescent, dark brown to medium brown, widest at anterior third ( Fig. 20 ). Elytron broadly convex, densely punctate with very fine, shallow punctures, punctures randomly scattered, not arranged in rows; elytron clothed with dense, very short, recumbent golden setae; humerus not protuberant. Lateral edge with distinct bead, bead sinuate ( Fig. 22 ); elytral epipleuron appearing narrow in ventral aspect ( Fig. 21 ). Elytron with very weak sutural stria in apical fourth. Elytral apex slightly acuminate ( Fig. 20 ).

Prosternum transverse, approximately 1.8 times as wide as long; anterior edge with weak bead, slightly deflexed to accommodate withdrawn head; prosternal process about as wide as long, without bead laterally, obtusely angled posteriorly ( Fig. 21 ). Mesoventrite pubescent, disc fully clothed with setae. Mesepisternum and mesepimeron excavated to accommodate folded front and middle legs. Mesepimeron extended posteriorly to metacoxae.

Legs long and slender, dark brown. Profemur densely pubescent. Protibia entirely pubescent. Protarsus with basal four tarsomeres densely pubescent, lacking tufts of long golden setae ventrally; apical tarsomere 1.5 times as long as preceding four tarsomeres combined, entirely glabrous ( Fig. 23 ). Mesocoxa with tuft of short golden setae basally. Mesofemur densely pubescent posteriorly, becoming less so anteriorly. Mesotibia completely glabrous, with few scattered setae, lacking small patch of short golden setae at apex; apex with excavation laterally for reception of tarsus. Mesotarsus with all tarsomeres entirely glabrous; apical tarsomere 1.5 times as long as preceding four tarsomeres combined ( Fig. 25 ). Metatrochanter globose. Metafemur densely pubescent. Metatibia pubescent to apical 1/16, apical 1/16 glabrous. Metatarsus with basal four tarsomeres entirely pubescent; apical tarsomere glabrous, 1.5 times as long as previous four combined ( Fig. 24 ).

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

Genitalia as illustrated, basal piece + parameres 2.2 mm long. Aedeagus slender and curved, becoming more curved at tapered tip. Parameres fused, pointed, with short, distinct lobes interiorly subapically ( Fig. 26 ).

Female. Length 4.6 mm; width 2.6 mm. Externally similar to male, females generally larger than males.

Intraspecific Variation. This species varies considerably in size, ranging from 4.6–5.0 mm long and 2.6–2.9 mm wide. Additionally, specimens vary slightly in color from dark brown to black. We have also noted that specimens in the series examined have differing levels of setation, with patches where setae have rubbed off, as well as patches where setae have become matted down with grease.

Etymology. This species is named for Grey Gustafson, a fellow aquatic coleopterist, who has collected many species of lutrochids in Venezuela.

Habitat and Distribution. The only known specimens of this species were collected on an expedition by the University of Puerto Rico in 1950. They were collected at two localities from the upper Rio Cunucunuma in Amazonas State, Venezuela, north of Cerro Duida, on the Culebra savannah (Drake and Capriles 1952) ( Fig. 7 ). The habits and microhabitat preferences of this species are unknown.

Figures

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 20 – 26. Lutrochus gustafsoni n. sp.: 20. Habitus, dorsal view; 21. Habitus, ventral view; 22. Habitus, lateral view; 23. Protarsus; 24. Mesotarsus; 25. Metatarsus; 26. Aedeagus, dorsal and lateral views (scale bar = 0.62 mm).