Dilobitarsus lambirensis Arimoto, 2025

Dilobitarsus lambirensis Arimoto , sp. nov.

( Figures 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Type material ( KIFDS). Malaysia, Sarawak, Miri , Lambir Hills National Park, by ultraviolet light traps. Holotype. Male, 17 m, 19–20 II 1996 [AA1214]. Paratypes ( 7 males). 1 male, 1 m, 6–7 X 1994 [AA1215]; 1 male, 17 m, 3–4 XI 1994 [AA1216]; 1 male, 35 m, 10–11 V 1994 [AA1217]; 1 male, 35 m, 11–12 VII 1994 [AA1218]; 1 male, 35 m, 21–22 XI 1998 [AA1219]; 1 male, 35 m, 21–22 XI 1998 [AA1220]; 1 male, 4 VII 2002 [AA1221].

Other material. 1 ex. (sex undetermined due to loss of abdomen), 35 m, 28–29 VI 1995 [AA1222; KIFDS] .

Male. Diagnosis. Dilobitarsus lambirensis is distinguished from the congeners by the following combination of characters: pronotum with a black circular pattern formed by black scale-like setae on anterior part ( Fig. 2A View FIGURE 2 ); elytra with V-shaped band formed by black scale-like setae ( Fig. 2A View FIGURE 2 ); frontal carina wide U-shaped in ventral view ( Fig. 3B, C View FIGURE 3 ); nasal plate moderately high laterally ( Fig. 3C View FIGURE 3 ); antennae not reaching pronotal posterior lateral apices by antennomere XI ( Fig. 2A View FIGURE 2 ); antennomere III 1.0–1.2 x longer than wide ( Fig. 3E View FIGURE 3 ); antennomeres IV–V 0.9–1.1 x longer than wide ( Fig. 3E View FIGURE 3 ); antennomere XI 1.95–2.1 x longer than wide ( Fig. 3E View FIGURE 3 ); pronotum with four tubercles ( Fig. 3G View FIGURE 3 : arrows); prosternum without carina anterad of procoxal cavities ( Fig. 3H View FIGURE 3 ); anterior edge of mesosternum with small median notch ( Fig. 3K View FIGURE 3 ); elytron broadly convex ( Fig. 4A View FIGURE 4 ); parameres with short lateral subapical barb ( Fig. 4K, L View FIGURE 4 ); apex of parameres beyond lateral subapical barb 0.1 x total length of paramere ( Fig. 4I, J View FIGURE 4 ), sub-trapezoidal and 1.0–1.15 x width at expansions in dorsal side ( Fig. 4K View FIGURE 4 ); apical mesal edge of parameres emarginate between proximal and distal apices ( Fig. 4K View FIGURE 4 ).

Measurements ( 8 specimens; holotype in parentheses). BL: 11.7–15.3 (14.3), BW: 3.30–4.27 (4.09), MAE: 1.76–2.25 (2.09), MBE: 1.11–1.47 (1.39), OI: 151–160 (151), PL: 3.87–5.08 (4.84), PML: 3.36–4.36 (4.17), PW: 3.13–3.96 (3.77), PAW: 1.94–2.39 (2.29), PLI: 123–131 (128), PWI: 159–165 (165), EL: 7.50–9.61 (9.32), EW: 1.59–2.12 (2.06), EI: 453–479 (453), BI: 188–197 (192).

Description. Body ( Fig. 2A, B View FIGURE 2 ) elongate; surface generally smooth and shining, with wax-like coating on dorsal side ( Fig. 2C View FIGURE 2 ), with large punctures; punctures on tubercles on pronotum smaller and denser; depression of hypomeron for reception of pro-femur and tibia without punctures; punctures at elytra smaller laterally and posterally; interspaces between punctures generally shorter than puncture diameter, but elytra interspaces vary from larger to smaller than puncture diameter. Color. Dorsal side black-brown but head, lateral margin of pronotum, and basal and apical parts of elytra red-brown; ventral side red-brown but prosternum and hypomera black-brown; mouthparts orange with labrum and mandibles black-brown, in some specimens maxillary palpi tinged with black; antennae and legs red-brown. Setae. Body covered with narrow scale-like setae ( Fig. 2C View FIGURE 2 ); each outside of tarsal claws with thick seta at its base ( Fig. 2D View FIGURE 2 : arrow). Head with orange setae; pronotum with white to yellow-white setae posteriorly and laterally, with black setae forming a black circular pattern medioanteriorly, bordered with scattered orange setae; elytra with white to yellow-white setae, and a black V-shaped setal band around the middle, on and around the V-shaped band with scattered orange setae; setae on pronotal tubercles denser and erect; ventral surface with white to yellow-white setae.

Head. Frontal region rectangular in dorsal view ( Fig. 3A View FIGURE 3 ); frons depressed mesally ( Fig. 3A, B View FIGURE 3 ); frontal carina complete and wide U-shaped ( Fig. 3B, C View FIGURE 3 ); nasal plate moderately high laterally, strongly narrowed medially and divided by frontal carina ( Fig. 3C View FIGURE 3 ), protruding beyond base of labrum ( Fig. 3D View FIGURE 3 ). Eyes 0.25–0.3 x longer than interocular distance in dorsal view. Labrum semicircular. Antennae extended beyond half-length of pronotum and not reaching pronotal posterior lateral apices by antennomere XI ( Fig. 2A View FIGURE 2 ); relative antennomere lengths: II<III– X<XI<I ( Fig. 3E View FIGURE 3 ); antennomere I cylindrical; II globular, 0.8–1.0 x longer than wide; III trapezoidal, 1.0–1.2 x longer than wide, 1.5–1.7 x longer than II; IV–X serrated; IV 0.9–1.1 x longer than wide, 0.9–1.1 x longer than III, 0.55–0.65 x longer than II–III combined; V 0.95–1.0 x longer than wide, 0.9–1.05 x longer than IV; XI oblong ovate, 1.95–2.1 x longer than wide, 1.4–1.8 x longer than X. Mandibles bidentate ( Fig. 3B View FIGURE 3 ). Apical maxillary palpomere securiform ( Fig. 3F View FIGURE 3 ), 1.6–1.8 x longer than wide, shorter than eye maximum length; apical edge broadly rounded.

Thorax. Pronotum sub-trapezoidal, 1.2–1.3 x longer than wide, widened posteriorly, broadly rounded laterally on posterior 2/3 and weakly constricted ahead of hind angles ( Fig. 2A View FIGURE 2 ), widest across posterior lateral apices, roundly convex, tallest at posterior tubercles ( Fig. 3D View FIGURE 3 ), with four tubercles, anterior two elevated slightly ( Fig. 3D View FIGURE 3 : white arrow, 3G: white arrows) and posterior two elevated strongly ( Fig. 3D View FIGURE 3 : black arrow, 3G: black arrows), without median longitudinal depression posteriorly; anterior angles strongly protruding beyond anterior edge ( Fig. 2A View FIGURE 2 ), rounded apically; anterior edge slightly emarginate medially in dorsal view ( Fig. 3A View FIGURE 3 ), weakly protruding medially in lateral view ( Fig. 3D View FIGURE 3 ); lateral carinae complete; posterior angles short, acute, without carina; posterior edge without sublateral incision near each hind angle, elevated medially. Hypomeron depressed for reception of proleg, carinate behind depression for reception of pro-femur and tibia; anterior angle rounded apically; posterior edge with three notches mesally ( Fig. 3H View FIGURE 3 : arrows). Pronotosternal sutures ( Fig. 2B View FIGURE 2 ) deeply grooved for reception of antennae, opened anteriorly; antennal groove extending to posterior angles of prosternum ( Fig. 3H View FIGURE 3 ), becoming shallower posteriorly. Prosternum with carinate anterior edge ( Fig. 2B View FIGURE 2 ); prosternal lobe weakly projecting, not reaching to the level of apices of anterior angles of prothorax ( Fig. 3D View FIGURE 3 ), without carina anterad of procoxal cavities. Prosternal process 2.9–3.2 x longer than procoxal cavity length, weakly curved dorsally behind procoxae ( Fig. 3D View FIGURE 3 ); dorsal lobe almost parallel-sided but gradually narrowed near apex in ventral view ( Fig. 2B View FIGURE 2 ); ventral lobe abruptly narrowed posteriorly in ventral view and forming median carina on posterior 1/3, without subapical tooth ( Fig. 3D View FIGURE 3 ); ventral margin broadly rounded in lateral view ( Fig. 3D View FIGURE 3 ); ventral apex not reaching dorsal apex; dorsal and ventral apices rounded in ventral and lateral views ( Figs 2B View FIGURE 2 , 3D View FIGURE 3 ). Scutellar shield tongue-shaped, roundly expanded posteriorly ( Fig. 3I View FIGURE 3 ), 1.2–1.3 x longer than wide, not visible in lateral view ( Fig. 3D View FIGURE 3 ); anterior part inclined anterior-downwards and posterior part parallel to elytral surface ( Fig. 3J View FIGURE 3 ); surface flat; anterior angles rounded; anterior edge weakly and roundly emarginated; apex broadly rounded. Mesosternum ( Fig. 3K View FIGURE 3 ): anterior edge with small median notch, not lobate and sinuate on each side; mesosternal cavity floor with a median elongate band with fine setae; mesosternal cavity almost parallel-sided anteriorly in ventral view; borders of mesosternal cavity straight anteriorly and then curved ventrally obtusely in lateral view ( Fig. 3D View FIGURE 3 ); mesosternal process between mesocoxae lower than mesocoxae, visible in lateral view ( Fig. 3D View FIGURE 3 ); posterior edge 0.23–0.27 x wider than total width of mesosternum, straight ( Fig. 3K View FIGURE 3 ); suture between mesosternum and metasternum present, but mesosternum and metasternum connate ( Fig. 3K View FIGURE 3 ). Mesepisternum excavate anteriorly ( Fig. 3K View FIGURE 3 ). Mesocoxal cavity closed to mesepisternum by mesosternum and mesepimeron ( Fig. 3H, K View FIGURE 3 ). Metasternum depressed for reception of mid-tarsi, sulcate medially and ahead of metacoxal cavities ( Fig. 2B View FIGURE 2 ). Metacoxal plate gradually narrowed toward outer side. Elytron broadly convex ( Fig. 4A View FIGURE 4 ), with longitudinal carina at humerus ( Fig. 3J View FIGURE 3 : arrow), without striae, without any pattern on ventral side ( Fig. 4B View FIGURE 4 ); apex rounded. Elytral apices not meeting at midline ( Fig. 2A View FIGURE 2 ). Hind wings ( Fig. 4C View FIGURE 4 ) fully developed, without veins CuA 1 and CuA 3+4; r4 translucent; mediomedial cross-vein between MP 1+2 and MP 3+4 present; mediocubital cross-vein between MP 3+4 and CuA 2 vestigial; radial cell more than 4 x wide. Tibiae without spurs ( Fig. 4D View FIGURE 4 ); relative tarsomere lengths: IV<III<II<V<I ( Fig. 4D View FIGURE 4 ); tarsomere IV with lobe ventrally ( Fig. 4D View FIGURE 4 : arrow); tarsal claws simple.

Abdomen. Ventrite V curved triangular, rounded apically ( Fig. 2B View FIGURE 2 ), 0.65–0.7 x longer than wide. Tergites and sternites VIII‒X yellow. Tergite VIII ( Fig. 4E View FIGURE 4 ) curved triangular, longer than wide, narrowed posterad, rounded apically. Sternite VIII ( Fig. 4F View FIGURE 4 ) hexagonal but with deep posterior median notch, shorter than wide, parallel-sided basally. Tergite IX ( Fig. 4G View FIGURE 4 ) shorter than wide; anterior margin widely emarginate; posterior median notch deep, 0.2–0.3 x total length of tergite IX. Tergite X ( Fig. 4G View FIGURE 4 ) semicircular, 1.0–1.1 x longer than wide, 0.6–0.7 x length of tergite IX. Sternite IX ( Fig. 4H View FIGURE 4 ) elongate, widely constricted laterally but expanded at posterior 1/3, rounded apically. Aedeagus ( Fig. 4I, J View FIGURE 4 ) yellow to brown, elongate. Phallobase 0.2–0.25 x total length of aedeagus, 0.7–0.8 x longer than wide. Median lobe gradually narrowed towards slender apex, not exceeding apices of parameres by its apex; basal struts 0.15–0.20 x total length of median lobe. Parameres separated ventrally, not constricted ahead of short lateral subapical barbs; apex beyond lateral subapical barb 0.1 x total length of paramere, sub-trapezoidal and 1.0–1.15 x width at expansions in dorsal side ( Fig. 4K View FIGURE 4 ), with two to four long setae dorsally, one to two long setae laterally and one to two long setae ventrally; ventral side 1/3 x width of dorsal side around apex ( Fig. 4L View FIGURE 4 : arrow); proximal apex broadly rounded ( Fig. 4K View FIGURE 4 : white arrow); distal apex rounded ( Fig. 4K View FIGURE 4 : black arrow); apical mesal edge shallowly emarginate between proximal and distal apices.

Female. Unknown.

Etymology. The specific epithet derives from Lambir Hills National Park, the type locality.

Distribution ( Fig. 1 View FIGURE 1 : triangle). Malaysia (Borneo).

Ecology. This species was collected in a lowland rainforest and may be observed year-round as specimens were collected in February, May, July, October, and November. All specimens were collected using light traps set on trees during the night.