Xenaclopus borneensis Arrow

Ocampo, Federico C. & Vaz-De-Mello, Fernando Z., 2008, The genus Xenaclopus Arrow (Coleoptera: Scarabaeidae): redescription and removal from the Aclopinae, with systematic notes, Zootaxa 1916, pp. 57-62 : 58-60

Xenaclopus borneensis Arrow

Redescription: Male. Length 3.82–4.11 mm, width 2.26–2.75 mm. Color: Head, pronotum, elytra brown to dark-brown; head progressively darker from clypeus to frons, pronotum with 2 darker areas at middle, elytral margins and suture darker than disc. Head ( Fig. 1 ): Eye canthus well developed, marginate with moderately long setae on anterior margin (note: setae not shown in illustration). Eyes well developed, rounded, not entirely divided by eye canthus. Frons slightly convex, surface sparsely punctate, sparsely setose; setae long, slender. Clypeus transverse; lateral margins oblique; anterior margin straight, slightly reflexed; frontoclypeal suture obsolete. Labrum protruding beyond clypeal margin, shape pentagonal with round apex with 5–6 long slender setae (setae not shown in illustration). Mandibles protruding beyond clypeal margin, broadly rounded externally, slightly concave dorsoventrally, lacking incisory teeth, molar area poorly developed ( Fig. 2 ). Labium ( Fig. 3 ) longer than wide, labial palpi with 3 palpomeres; surface setose, setae dense to moderately dense, long, slender. Maxillae poorly developed, maxillary palpus with 4 palpomeres ( Fig. 4 ). Antennae ( Fig. 5 ) with 9 antennomeres, antennal club with 3 antennomeres; sixth antennomere greatly reduced, antennal club longer than antennomeres 1–6 combined. Pronotum ( Fig. 6 ): Convex, wider than long. Surface sparsely punctate, setose; setae long, slender. Marginal bead complete; anterior margin concave, with membrane; lateral margins broadly rounded; posterior margin slightly sinuous. Anterior angles nearly right-angled; posterior angles broadly rounded. Scutellum ( Fig. 6 ): Large, triangular apex acute, surface sparsely punctate. Elytra ( Fig. 6 .): Convex, globose, lateral margins broadly rounded. Elytral striae absent sparsely punctate, sparsely setose; setae moderately long; pseudoepipleura poorly developed. Ve n te r ( Fig. 7 ): Metasternum narrow, 0.51 times as long as wide; 6 ventrites exposed medially; penultimate ventrite as long as previous three ventrites combined (at middle), membranous on apical margin. Pygidium not exposed beyond elytral margin, wider than long, surface sparsely setose; setae long, slender. Abdominal spiracles dorsal to sternotergal suture. Legs: Protibiae with 3 teeth ( Fig. 8 ), protibial spur slightly curved. Mesotibiae and metatibiae ( Fig. 9 ) with short, medial, transverse carinae. Mesotibial and metatibial ( Fig. 10 ) apex with fringe of thick setae; mesotibial and metatibial spurs contiguous, metatibial spurs ( Figs. 9–10 ) both set below tarsal articulation; inner spur longer than outer spur. Metatibial tarsal insertion simple, without notch; metatibial apical margin entire. Tarsus approximately as long as tibiae. Tarsomeres 1 and 5 each longer than 2, 3, 4 individually; all tarsi with long, apical setae ( Fig. 9 ). Protarsal claws curved, outer claw bifid (split) ( Fig. 11 ). Mesotarsal and metatarsal claws simple (not bifid), symmetrical ( Figs. 9 ). Male Genitalia: phallobase dilated basally, elongate apically, entirely open ventrally; parameres simple, symmetrical, elongate; paramere apex acute, angled in relation to phallobase ( Figs. 12–13 ), genital segment (spiculum gastrale) poorly sclerotized, Y-shaped with very wide basal arm ( Fig. 14 ).

Remarks. Females are unknown to us.

Figures

FIGURES 1 – 5. Xenaclopus borneensis. 1. head, dorsal view; 2. left mandible, dorsal view; 3. labium, ventral view; right maxilla, ventral view; 4. left antenna, dorsal view.

FIGURES 6 – 7. Xenaclopus borneensis habitus. 6. dorsal view; 7. ventral view.

FIGURES 8 – 14. Xenaclopus borneensis. 8. left protibia, dorsal view; 9. right metatibia, dorsal view; 10. right metatibial apex, apical view; 11. left proclaws, ventral view; 12. aedeagus, lateral view; 13. parameres, apical view; 14. genital sclerite (spiculum gastrale), ventral view.