Pentarthrum chinensis Omar and Zhang

Omar, Youssef M., Zhang, Runzhi & Davis, Steven R., 2010, Description of a new species of Pentarthrum Wollaston (Coleoptera: Curculionidae: Cossoninae) from China with an annotated checklist to species of the World, Zootaxa 2629, pp. 47-60 : 48-51

Pentarthrum chinensis Omar and Zhang , sp. nov.

( Figs. 1–36)

Type series. Holotype: male, China, Guangxi Province; Mubian, coll. Shanggen XING, 22 Jul.1956, host plant Maize; Allotype: female, same data as holotype. Paratypes: ten males, four females. CHINA, three females, same data as holotype; one female, Yunnan Province, [Jinping], 19 Jun.1958; four males, same data as holotype; two males, Yunnan Province, [Xiaomengyang, Xishuangbanna], coll. Shuyong WANG, 23 Oct.1957; altitude 850 m; host plant unknown; one male Yunnan Province [Menghai], 25 Aug.1958; one male, Yunnan Province [Jinping], 19 Jun.1958; two males, Yunnan Province [Mengla], 29 Jul.1958; (IOZCAS).

Diagnosis. Head constricted behind eyes, area before constriction wrinkled, strongly and coarsely punctate; elytra nearly parallel-sided until declivity then gradually tapering towards apex, suture slightly elevated above dorsum; intervals one and three dilated at apex and weakly elevated; abdomen with pale yellowish, long tufts of setae protruding from tergites seven and eight and visible laterally.

Description. Male measurements. BL: 2.78–2.81 mm; EL: 1.56–1.76 mm; EWB: 0.59–0.68; EWW: 0.61–0.70 mm; PL: 0.68–0.76 mm; PW: 0.53–0.66 mm; RL: 0.38–0.42 mm; RWA: 0.17–0.21 mm; RWB: 0.13–0.17 mm; AL: 0.55–0.57 mm; ASL: 0.19–0.23 mm; AFL: 0.19–0.21 mm; ACL: 0.13–0.17 mm; ACW: 0.08–0.09 mm. Female measurements: BL: 2.63–2.78 mm; EL: 1.50–1.56 mm; EWB: 0.57– 0.57 mm; EWW: 0.59– 0.59 mm; PL: 0.68–0.70 mm; PW: 0.53–0.57 mm; RL: 0.44– 0.44 mm; RWA: 0.17– 0.17 mm; RWB: 0.10–0.11 mm; AL: 0.53–0.55 mm; ASL: 0.19–0.21 mm; AFL: 0.19–0.21 mm; ACL: 0.13–0.15 mm; ACW: 0.06–0.08 mm.

FIGURES 5 –12. Male terminalia and associated tergites. 5–6) aedeagus, dorsal view; 7) aedeagus, lateral view, and tegmen; 8) aedeagus, enlargement of median lobe and internal sac; 9) 8th sternite and 9th sternite + spiculum gastrale; 10) tergite 8, showing elongate, forked setae; 11) tergite 7, showing elongate, forked setae; 12) tegmen, dorsal view.

Habitus: Oblong, fusiform, slender, slightly compressed ( Figs. 1–4). Color: Light brown. Rostrum: Convex, curved, base narrower than apex, coarse, with oblong, fine punctures with minute, appressed setae at anterior half of punctures ( Fig. 28 ); antennal insertion at basal half of rostrum in males and close to the middle in females; pale yellowish, long setae ventrally. Scrobe: Shallow, short, upper margin at same level as dorsal margin of eye, triangular. Antenna: light brown, short, with pilose club; scape short, stout, clavate, smooth, reaching slightly beyond anterior margin of eye. Funicle: Composed of five segments with long, erect setae; compact, not longer than scape. Club: Longer than wide, global, with long, erect setae towards apex. Eyes: Sub-circular, black, strongly convex, with coarse, convex facets; clearly separated from head, located ventrolaterally; temple swollen. Head: Oval, small, strongly constricted behind eyes, area before constriction wrinkled, coarsely punctate, after constriction smooth and shiny, with numerous punctures near constriction. Pronotum: Longer than wide, constricted at apex; constriction visible laterally and rather obsolete in dorsal view; narrowed towards apex, slightly rounded laterally, coarse, with sub-circular punctures with interspace half to one time diameter of puncture; disc flat, base truncate. Scutellum: Dark brown, small, cordiform, smooth, glossy, flat, impunctate. Elytra: Nearly parallel-sided until declivity, then gradually tapering towards apex; glossy, dorsum convex, suture slightly elevated above dorsum, base truncate, striae with large, deep, circular punctures, distance between punctures half time puncture diameter, wider than intervals ( Figs. 29, 30 ); intervals sub-equal, convex, impunctate, intervals one and three dilated at apex and feebly elevated, interval one with some appressed setae at apex, interval nine raised and continuous beyond declivity until apex; elytron apex not expanded laterally, reaching below level of abdomen; abdomen with tuft of long, whitish setae along posterior margins of tergites seven and eight (Figs. 10, 11); humeri truncated. Sclerolepidia along dorsal margin of metasternum appearing to be the digitate type 2C ( Figs. 31, 32 ), in which digiti most often meet apically ( Lyal et al. 2006). Venter: Glossy, coarse; pro-sternum long, with coxal cavity closed, fore-coxae separated with distance shorter than coxa diameter; meso-sternum transverse, meso-coxae separated with distance slightly wider than one time diameter of coxa, coxal cavity closed; meta-sternum coxal cavity open, coxae separated the same distance as meso-coxae. Ventrites: I and II confluent together, slightly raised above other ventrites; III and IV narrow, with a single row of fine, erect setae along lateral margins; V transverse, posterior margin rounded, with erect setae ( Figs. 26, 27 ). Legs: Femur coarse, robust, short; tibia smooth, glabrous, shorter than femur, width nearly uniform throughout, with strong, arcuate uncus; tarsus with five tarsomeres, with some pale yellowish setae ventrally ( Figs. 34, 36 ); tarsomere three simple (not lobed); tarsomere five longer than others, curved, glossy, glabrous; tarsal formula five-five-five; tarsal claws (pre-tarsal ungues) simple, long, curved ( Fig. 33 ); tarsomeres sparsely punctured ventrally.

Male and female terminalia and associated tergites as depicted in figures 5–12 and 13–16, respectively. Mouthparts, proventriculus, meso- and metanota, metendosternite, and hind wing venation as depicted in figures 17–25.

Etymology. The specific epithet is derived from the country of the type locality, China.

Distribution. Guangxi and Yunnan Provinces, China.

Sexual dimorphism. Point of antennal insertion at basal half of rostrum in male and close to the middle in female as well as male with long, dense tufts of pale yellowish setae overhanging from the last two tergites and a more extended elytral apex; female with similar features but setae shorter and sparser than those of male and with a less-extended elytral apex.

Notes about related species. Pentarthrum chinensis can be differentiated by its short rostrum (shorter than pronotum), prominent eyes, constricted head behind the eyes, and constricted rostrum along basal half. One character, distinguishing P. chinensis from other Pentarthrum species, is the long, pale yellowish tufts of setae overhanging from the last two tergites. Other characters include its length (including rostrum) of 2.63 – 2.81 mm, rostrum at base narrower than apex, not sulcate at base; interval impunctate, not raised or carinate at all along basal one half of elytra except ninth interval raised and extending beyond declivity until apex; protibiae setose along their third distal inner margins, parallel-sided. The three Oriental region species differ from P. chinensis as follows ( Wollaston 1854, 1861, 1873a, 1873b, 1878; Roelofs 1876; Schaufuss 1887; Broun 1909; Champion 1914; Marshall 1926; Folwaczny 1973): P. wollastoni Roelofs 1876 has the rostrum almost parallel sided; head slightly constricted behind eyes; frons with elongated impression; elytra deeply punctatosulcate; intervals finely punctated; third tarsal segment bilobed; P. celebensis Schaufuss 1887 has a slender rostrum; minutely wrinkled head; deeply and densely punctured pronotum; elytra deeply quadrately punctatestriate; intervals with row of punctures, which have fine setae; front legs sinuous; and P. m u s a e Marshall 1926 has the rostrum nearly as long as the pronotum; intervals slightly convex, each with a row of extremely minute spaced punctures, lateral intervals sharply carinate in apical half.

Figures

FIGURES 26 – 36. SEM micrographs. 26) abdominal venter; 27) enlargement of ventrite 5; 28) head and anterior portion of prothorax, lateral view; 29) elytron (left side); 30) enlargement of portion of elytron disc; 31) metathorax, lateral view, showing sclerolepidia; 32) enlargement of sclerolepidia; 33) distal end of tarsus and tarsal claws (pretarsal ungues); 34) pro-leg; 35) meso-leg; 36) meta-leg.