Lutrochus minutus, 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 : 301-302

Lutrochus minutus n. sp.

( Figs. 6 , 48 –54)

Type Material. Holotype male: “ VENEZUELA:Tachira State/7° 35.038ʹ N, 72° 10.340ʹ W, 472 m / El Tama National Park; 16.vii.2009 / leg. Short, Sites, Garcia, Inciarte/ Gustafson & Camacho/HG-vapor light VZ09-0716- 07A” “SEMC0876083/KUNHM-ENT”. Holotype deposited in MIZA. Paratypes (9): VENEZUELA: Tachira State: Same locality data as holotype. Paratypes will be deposited in: 1 in MIZA, 1 in MALUZ, 1 in NMW, 5 in SEMC, and 1 in USNM.

Diagnosis. This species is smaller than any other described Lutrochidae in South America, and can be distinguished from all others by several unique characters: strongly punctate elytra ( Fig. 51 ), pubescent mesotibiae, and parameres that are not as fused as in other lutrochid species (Fig. 54).

Description. MALE.—Length 2.4 mm; width 1.3 mm. Body wedge-shaped, dark brown to black, densely pubescent; clothed with short, fine, recumbent light golden setae and long, erect light golden setae ( Fig. 48 ).

Head broad, broadly rounded. Eye rounded, large, with short, golden interfacetal setae; eyes projecting slightly from outline of head. Antenna short, reaching slightly past anterior border of pronotum, apical 9 segments short, reddish-brown and clavate, clothed with short golden setae (Fig. 53). Frontoclypeal suture indistinct. Clypeal margin straight, with brush of long setae apically. Apical margin of labrum straight, lacking apical setal brush. Labrum clothed with sparse, blunt setae at basal half, apical half glabrous. Mandibles large, dark brown, sickleshaped; apex of mandible with two teeth. Maxilla with 4-segmented palpus, apical palpomere flattened and weakly triangular, truncate at apex. Labial palpus 3-segmented; apical palpomere cylindrical.

Pronotum pubescent, dark brown, two times as wide as long at base, sinuate at base, densely clothed in recumbent setae in a wavy pattern and long, erect setae ( Fig. 48 ); lateral edges strongly convergent. Lateral edge of pronotum with distinct bead, explanate apically. Posterior margin of pronotum straight anterior to scutellum. Disc of pronotum broadly convex. Scutellum triangular, about as wide as long ( Fig. 52 ). Hypomeron not excavate posteriorly ( Fig. 50 ). Area lateral to scutellum with distinct space between elytron and pronotum ( Fig. 48 ).

Elytron pubescent, dark brown, widest at base. Elytron slightly convex, with dense, deep, confused punctation; clothed in dense recumbent setae in a wavy pattern, and long, erect setae ( Fig. 48 ). Elytral humerus strongly protuberant. Lateral edge with distinct bead; epipleuron appearing narrow in ventral aspect ( Fig. 49 ). Elytral apex strongly acuminate ( Fig. 48 ).

Prosternum transverse, approximately as wide as long; anterior edge with strong bead, slightly deflexed to accommodate withdrawn head; prosternal process about as wide as long, with bead laterally, pointed posteriorly ( Fig. 49 ). Mesoventrite pubescent, lacking glabrous patch medially. Mesepisternum and mesepimeron continuous, not excavate to accommodate folded front and middle legs. Mesepimeron extended posteriorly nearly to metacoxae.

Legs long and slender. Profemur densely pubescent. Protibia entirely pubescent. Protarsus with all tarsomeres pubescent, clothed with dense, golden setae; apical tarsomere as long as preceding four tarsomeres combined. Mesocoxa lacking tuft of long golden setae basally. Mesofemur densely pubescent posteriorly, becoming less so anteriorly. Mesotibia entirely pubescent, with narrow glabrous band. Mesotarsus with all tarsomeres glabrous, except for tufts of golden setae ventrally on all tarsomeres; apical tarsomere almost as long as preceding four tarsomeres combined. Metatrochanter globose, without posterior extensions. Metafemur densely pubescent. Metatibia entirely pubescent. Metatarsus pubescent, with pubescence becoming more sparse near apex. Apical metatarsomere nearly as long as previous four combined.

Abdomen densely pubescent, with five ventrites. First ventrite shallowly excavated for reception of folded hind legs ( Fig. 49 ). Apical ventrite broadly rounded.

Genitalia as illustrated, basal piece + parameres 1.1 mm long, strongly curved. Aedeagus slender and curved, becoming more curved at tapered tip. Parameres slightly fused at the base, pointed, with distinct lobes interiorly subapically (Fig. 54).

Female. Length 2.4 mm; width 1.4 mm. Externally similar to male, females generally larger than males.

Intraspecific Variation. This species varies only slightly in size, ranging from 2.4–2.6 mm long and 1.3–1.5 mm wide. Additionally, specimens vary slightly in color, from dark brown to medium brown. 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 “ minutus ” because it is the smallest lutrochid described from South America.

Habitat and Distribution. This species is only known from the type locality in Tachira State, Venezuela, and nothing is known of the biology or habits, as all individuals were collected at a mercury vapor lamp.

Remarks. Lutrochus minutus represents a unique body plan among Lutrochus species, with numerous characters setting it apart from the other South American lutrochids, including strongly punctate elytra, pubescent mesotibiae, and parameres that are not as fused as in other lutrochid species. Additionally, this species lacks the excavations in the hypomeron and elytral epipleuron characteristic of other Lutrochidae . It does, however, have the necessary characters that place it in Lutrochidae – expanded apical maxillary palpomeres, short, clavate antennae, and interfacetal setae all point clearly to its placement in the Lutrochidae .

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 48 – 52. Lutrochus minutus n. sp.: 48. Habitus, dorsal view; 49. Habitus, ventral view; 50. Habitus, lateral view; 51. Scutellum; 52. Elytra, showing sculpturing 53. Head, three-quarters view, showing shape of apical maxillary palpomere; 54. Aedeagus, dorsal and lateral views (scale bar = 0.62 mm).