Lutrochus violaceus, 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 : 304-306

Lutrochus violaceus n. sp.

( Figs. 2 , 7 , 58 –63)

Type Material. Holotype male: “ VENEZUELA:Merida State/8° 35.355ʹ N, 71° 13.926ʹ W, 1646 m / N. of Ejido, Rt. 4 river x-ing/ 10.vii.2009; leg. Shepard/ gross sample; VZ09-0720-02Z” “SEMC0929353/KUNHM-ENT”. Holotype deposited in MIZA. Paratypes (66): VENEZUELA: Mérida State: “ VENEZUELA:Merida State/ 8° 51.933ʹ N, 70° 37.131ʹ W, 1682 m / Cascada Velo de la Novia; 24.i.2012 /leg. Short, Arias, & Gustafson/ Logs & Kicknetting” (15 specimens SEMC). “ VENEZUELA:Merida State/ 8° 52.423ʹ N, 70° 37.611ʹ W, 1616 m / ca. 12 km SE Santo Domingo /leg. Short, Arias, & Gustafson/ 22.i.2012; log and stick jams in/ river; VZ12-0122-03B” (44 specimens SEMC). “ VENEZUELA:Merida State/ 8° 51.933ʹ N, 71° 37.131ʹ W, 1682 m / ca. 12 km SE of Santo Domingo / 19.vii2009; leg. W. Shepard/gross sample; VZ09-0719-02Z” (5 specimens SEMC). “ VENEZUELA:Merida /Merida at zoo/ 14 I 06 /Rio Milla/ [reverse] AS-06-026” “A.E.Z. Short/ P.J. Torres” (2 specimens SEMC). Paratypes will be deposited in: 5 in MIZA, 2 in MALUZ, 1 in NMW, 56 in SEMC, and 2 in USNM.

Diagnosis. This species can be distinguished from all other described Lutrochidae by the distinctive violet sheen dorsally and distinctive apical protarsomere, which is pubescent, although more sparse in apical half ( Fig. 58 ).

Description. MALE.—Length 4.5 mm; width 2.7 mm. Body wedge-shaped and strongly convex, reddishbrown to black, densely pubescent; clothed with short, fine, slightly recumbent and erect golden setae ( Fig. 55 ).

Head broad, broadly rounded. Eye rounded, small, with short, golden interfacetal setae; eyes smooth within outline of head. Antenna short, reaching slightly past anterior border of pronotum, medium brown and clavate, clothed with short golden setae. Frontoclypeal suture indistinct. Clypeal margin straight, with brush of long black setae apically, setae nearly as long as labrum. Apical margin of labrum sinuate, with apical setal brush, lateral setae three times as long as medial setae. Labrum clothed with sparse golden setae. Mandibles large, dark brown, sickleshaped; apex of mandible with three 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, 2.2 times as wide as long at base, bisinuate at base ( Fig. 55 ). Lateral edge of pronotum with distinct bead, broadly rounded. Posterior margin slightly notched anterior to scutellum. Disc of pronotum broadly convex. Scutellum sub-triangular, about as wide as long. Hypomeron excavate posteriorly to accommodate femur.

Elytron pubescent, dark brown, with slight bluish to violet metallic sheen, widest at basal 1/3. Elytron broadly convex, densely punctate with very fine, shallow punctures, punctures randomly scattered, not arranged in rows; elytron clothed with dense, short, recumbent golden setae and short, erect, golden setae; humerus not protuberant ( Fig. 55 ). Lateral edge with distinct bead ( Fig. 57 ); elytral epipleuron appearing narrow in ventral aspect ( Fig. 56 ). Elytron with very weak sutural stria in apical fourth ( Fig. 55 ). Elytral apex slightly acuminate.

Prosternum transverse, approximately 1.6 times as wide as long; anterior edge with strong bead, slightly deflexed to accommodate withdrawn head; prosternal process about as wide as long, lacking lateral bead, broadly rounded posteriorly ( Fig. 56 ). Disc of mesoventrite entirely pubescent. Mesepisternum and mesepimeron excavated to accommodate folded front and middle legs. Mesepimeron extended posteriorly to metacoxae.

Legs long and slender, reddish-brown. Profemur densely pubescent. Protibia entirely pubescent. Protarsus with basal four tarsomeres pubescent, with tufts of golden setae ventrally; apical tarsomere 1.2 times as long as preceding four tarsomeres combined, glabrous ventrally, pubescent dorsally ( Fig. 58 ). Mesocoxa with tuft of long golden setae basally. Mesofemur densely pubescent posteriorly, becoming less so anteriorly. Mesotibia completely glabrous, with small patch of golden setae at apex; apex excavated for reception of tarsus. Mesotarsus with all tarsomeres glabrous, except for tufts of golden setae ventrally on all tarsomeres; apical tarsomere 1.2 times as long as preceding four tarsomeres combined. Metatrochanter globose, with small posterior projection. Metafemur densely pubescent. Metatibia entirely pubescent, except apical 1/16 glabrous. Metatarsus entirely glabrous, with apical tarsomere as long as previous four combined ( Fig. 59 ).

Abdomen densely pubescent, with five ventrites ( Fig. 55 ). First ventrite shallowly excavated for reception of folded hind legs. Apical ventrite broadly rounded.

Genitalia as illustrated, basal piece + parameres 2.6 mm long. Aedeagus slender and straight, becoming slightly curved just before tapered tip. Parameres fused, pointed, with distinct lobes interiorly subapically ( Fig. 60 ).

Female. Length 5.1 mm; width 2.9 mm. Externally similar to male, females generally larger than males.

Intraspecific Variation. This species varies considerably in size, ranging from 4.5–5.5 mm long and 2.7–3.0 mm wide. Additionally, specimens vary slightly in color and luster – from dark brown to black, and from slightly metallic to not metallic. Some specimens 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 “ violaceus ” because of the presence of a blue-violet sheen on the elytra, which is unique among described Lutrochidae .

Habitat and Distribution. This species is known from several localities in the Mérida Andes ( Fig. 7 ), all of which are at elevations above 1500 m. Specimens of L. violaceus have been found clinging to logs and woody debris in small to medium sized (2–7 m wide) mountain streams ( Fig. 2 ).

Figures

FIGURE 2. Habitat of Lutrochus violaceus: A) Venezuela, Mérida State, 12 km SE Santo Domingo (collecting event VZ 12 - 0122 - 03 B). Specimens (B) were found clinging to submerged stick and log debris (C).

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 55 – 60. Lutrochus violaceus n. sp.: 55. Habitus, dorsal view; 56. Habitus, ventral view; 57. Habitus, lateral view; 58. Protarsus; 59. Metatarsus; 60. Aedeagus, dorsal and lateral views (scale bar = 0.50 mm).