Pelenomus canaliculatus (Fåhraeus, 1843), Fahraeus, 1843

Yang, Lujing, Huang, Junhao, Zhang, Runzhi & Wu, Hong, 2013, A review of the genus Pelenomus Thomson (Coleoptera: Curculionidae: Ceutorhynchinae) from China, Zootaxa 3652 (4), pp. 401-423 : 405-407

Pelenomus canaliculatus (Fåhraeus, 1843)

( Figs.5–8 , 25–28, 49–56, 88)

Description. Male. LB: 2.12 mm; LR: 0.44 mm; WP: 0.83 m;, LP: 0.57 mm; WE: 1.28 mm; LE: 1.44 mm. N = 1 for all measurements. Dark brown in general appearance; head and pronotum brown; antennae, eyes and legs reddish-brown. Habitus as shown in Figs. 5 and 6 .

Vestiture moderately dense. Head (Figs. 25–26) covered with dense brown hairlike scales on disc and dense white oval scales behind eyes; rostrum with sparse brown hairlike scales. Pronotum ( Fig. 5 ) mostly covered with dark brown linear scales, and with white oval scales scattered along the median sulcus and dense on lateral sides. Elytra ( Fig. 5 ) with scutellar spot formed of imbricated brown oval scales; intervals bearing 3–4 rows of dark brown linear scales, mingled with white oval scales, forming irregular spots; striae bearing a fine hairlike scale in each puncture. Underside ( Figs. 6–7 ) covered with sparse white oval scales. Legs ( Fig. 6 ) moderately clothed with dense white oval scales on femora and linear scales on tibiae. Pygidium ( Fig. 8 ) with white oval scales.

Rostrum robust, 0.77 times longer than pronotum. In dorsal view (Fig. 25), rostrum slightly widened basally, almost parallel-sided in basal 2/3, after the antennal insertion gradually widening toward the apex; dorsal suface without distinct median carina nor sulcus, with shallow elongate medium-sized punctures on each side, forming two-three lines of ill-defined wrinkles; apical part of rostrum smooth, shining, with sparse fine punctures. In lateral view (Fig. 26) rostrum slightly curved, dorsal outline clearly more steeply curved than the ventral one. Frons faintly narrower than the base of rostrum, then strongly widened basally; frons and vertex uniformly covered with shallow medium-sized punctures. Antennae inserted at the apical part of rostrum, scape 0.77 times as long as funicle, length ratio of funicular segments I: II: III: IV: V: VI = 3.89: 2.56: 1.96: 1.22: 1.00: 1.11 and width ratio = 2.32: 1.18: 1.00: 1.18: 1.45: 1.45.

Pronotum ( Fig. 5 ) 1.46 times wider than long, 0.39 times as long as and 0.65 times as wide as elytra, bearing a pair of tubercles in the middle of lateral sides. Dorsum coarsely punctured, with shallow median suture; apical margin moderately raised. Sides moderately rounded, widest at middle, weakly converging toward the subapical constriction. Scutellum subovate.

Elytra ( Fig. 5 ) oval, 1.13 times longer than wide, 2.54 times longer and 1.55 times wider than pronotum; sides subparallel, gently convergent toward the subapical calli; humeral calli moderately prominent; subapical calli weakly prominent. All intervals flattened, almost the same in width and height, nearly three times wider than striae, each with 3–4 rows of large and acute squamate granules; striae moderately marked, with distinct punctures.

Legs ( Fig. 6 ) with procoxae separated by a distance about the same as basal width of rostrum, middle coxae separated by a distance equal to apical width of rostrum. Legs slender; femora clavate, without tooth; middle tibiae with sharp mucro; tarsi moderate in length; claws free, slender, not appendiculate.

Prosternum simple, without prosternal canal. Venter ( Fig. 7 ) coarsely and moderately densely punctured; ventrite I and II flattened on the dorsum; ventrite V shallowly depressed along the apical margin, limited by a pair of sharp denticles; length ratio of ventrites I: II: III: IV: V = 3.05: 1.73: 0.58: 0.53: 1.00 and width ratio = 1.80: 1.55: 1.34: 1.21: 1.00.

Pygidium ( Fig. 8 ) 1.33 times wider than long. Sternite IX ( Fig. 53 ) with spiculum gastrale relatively short, much shorter than the aedeagal body, and slightly longer than its apodeme, bent leftward. Tegmen ( Fig. 52 ) with apodeme short and robust, nearly one third as long as diameter of tegminal ring, subparallel along entire length, truncate at base. Aedeagal body ( Figs. 49–51 ) long and slender in profile, more or less curved downward in the basal 1/3, then moderately bent upward in the apical 1/4; sides subparallel in basal 2/3, slightly broadened to apical 1/5, then gradually convergent apically, rounded at apex. Basal part of endophallus ( Fig. 49 ) with two pairs of plate-like sclerites, bunch of dense minute spicules between the plates, and sparse dentiform spicules widely distributed.

Female. LB: 2.02–2.22 mm (mean, 2.12 mm); LR: 0.55– 0.42 mm (0.48 mm); WP: 0.76–0.89 mm (0.83 mm); LP: 0.52–0.62 mm (0.57 mm); WE: 1.24–1.44 mm (1.34 mm); LE: 1.33–1.55 mm (1.44 mm). N = 2 for all measurements.

Rostrum (Figs. 27–28) 0.81–0.88 times longer than the pronotum. Pronotum 1.43–1.46 times wider than long. Elytra 1.07–1.08 times longer than wide. Tibiae not mucronate. Ventrite I and II moderately inflated and punctured; ventrite V slightly inflated without concavity.

Pygidium 1.20 times wider than long. Sternite VIII ( Fig. 54 ) with several minute setae near the apex; arms very wide, 1.7 times longer than apodemes, nearly as long as coxite and stylus combined, widely separated, with inner margins shallowly arcuate and gradually broadened apically, with outer margins broadly arcuate; apodemes short, slender and strongly curved. Coxites robust ( Fig. 55 ), nearly four times longer than styli; styli apicolaterally inserted, moderate in length, nearly three times longer than wide. Spermatheca ( Fig. 56 ) with cornu robust; collum very weakly convex; ramus strongly marked; insertions of the duct and gland close to each other. Otherwise practically as in male.

Distribution. China (Heilongjiang— new record; Fig. 88 ), Eurasia (Colonnelli, 2004).

Specimens examined. HEILONGJIANG. 1 male and 1 female, Harbin, 31-V-1943, IOZ(E) 895183–895184 (IZCAS). 1 female, North Eastern China, IOZ(E) 895226 (IZCAS).

Biological notes. The host plant of the species was firstly recorded as Polygonum mite Schrank (Wagner, 1939) . Hoffmann (1954) cited Potamogeton natans L. ( Potamogetonaceae ) as a host plant in France. Later, Myriophyllum verticillatum L. and M. spicatum L. ( Haloragidaceae ) were confirmed as host plants by Dieckmann (1972), who also observed its larvae feeding and pupating on the leaves. According to Caillol (1954), Colonnelli (2004) listed Polygonum hydropiper as another host plant in his catalogue. In Japan, this species feeds on Myriophyllum aquaticum (Vell.) Verdc. which typically grows in freshwater streams, lakes and rivers (Yoshitake, 2011). Ecological information on this species and its host plant associations in China are lacking at the moment.

Remarks. This is a new record to China. Among the Chinese species, P. canaliculatus shares with P. waltoni relatively dense vestiture, whereas P. curvatus , P. quadricorniger and P. ro e lo fs i are covered with sparse dark brown linear scales. However, P. w a lt o ni has the rostrum longer than the pronotum, where P. canaliculatus has the rostrum distinctly shorter than the pronotum. In addition, in P. canaliculatus brown linear dark scales are prevalent on the elytra and ventrite V is shallowly concave and limited by a pair of sharp denticles, while in P. waltoni the elytral intervals are densely covered with white oval scales and ventrite V lacks a concavity and denticles.

Figures

FIGURE 88. Geographic distribution of the genus Pelenomus in China.

FIGURES 5 – 8. Pelenomus canaliculatus, male. (5) Dorsal habitus. (6) Lateral Habitus. (7) Venter. (8). Pygidium. Scale bar: 0.50 mm for 5 – 7; 0.25 mm for 8.

FIGURES 49 – 56. Male and female genitalia of Pelenomus canaliculatus from Heilongjiang, China. (49 – 53) Male. (49) Aedeagus, dorsal view. (50) Apex of the aedeagal body, dorsal view. (51) Aedeagus, lateral view. (52) Tegmen. (53) Sternites IX. (54 – 56) Female. (54) Sternite VIII. (55) Coxite and stylus. (56) Spermatheca. Scale bar: 0.20 mm for 49 – 54, 0.10 mm for 55 – 56.