Platambus striatus (ZENG & PU 1992) Brancucci, M. & T, China., 2006

Brancucci, M. & T, China., 2006, Platambus striatus (ZENG & PU 1992) a valid species from south-western China (Coleoptera: Dytiscidae), Linzer biologische Beiträge 38 (2), pp. 1397-1402 : 1397-1402

Platambus striatus (ZENG & PU 1992) comb. nov., stat. revid. ( Figs 1-5 )

Hydronebrius striatus ZENG & PU 1992: 482 (orig. descr., Sichuan); NILSSON 1995: 57 (as synonym of Platambus lineatus GSCHWENDTNER 1935 ); 2000: 35 (in synonymy); 2001: 40 (in synonymy).

M a t e r i a l s t u d i e d 13 and 1♀: " China, Sichuan Prov., Moxi [ca. 29.40N 102.06E], 25.VI.1999, V. Beneš leg." ( NMPC). 1♀: " China, Yunnan, Daju, 50 km N Lijiang, 27°21’N 100°19’E, 27.-28.VI.1992, E. Jendek leg." ( NMW). Text in Chinese : 1♀ " China, Yunnan, Baoshan City , 6.VI.1983, D. Dong leg." ; 13: Idem , 7.VI.1983 ; 13 and 1♀: Idem 12.VI.1983 ; 2♀♀: Idem : 15.VIII.1983 ( ISAS, NHMB) .

D e s c r i p t i o n: Body elongate-oval, slightly convex, yellow with a black pattern as shown in Fig. 1 .

Measurements: Total body length: 7.2-8.1 mm; width: 3.5-3.9 mm.

Head completely yellow, somewhat darkened alongside eyes and distinctly on vertex. Reticulation consisting of well impressed polygonal meshes, irregular in size, with 1-3 very small punctures within them and larger ones on their intersections. Large punctures forming a row alongside eyes, and distinct fronto-clypeal fovea.

Pronotum of variable shape ( Fig. 2 ). In some specimens slightly cordiform, broadest before middle, lateral margin rounded in anterior half, but almost straight in posterior half, posterior angles obtuse, and pronoto-elytral angle distinct. On the other hand, some specimens have pronotum with posterior angles protruding, thus pronotum widest basally, and pronto-elytral angle indistinct. Colour yellow with generally a broad black basal band. A more or less distinct blackish band also along anterior margin. Reticulation similar to that on head. Anterior margin with a row of large setigerous punctures, and a similar row near posterior margin broadly interrupted at middle. Lateral margin thinly but distinctly bordered.

1399

Elytra yellow with a thin black transverse basal band, a sutural and two discal black stripes, as well as two lateral longitudinal black spots of variable size, which could be completely reduced in some specimens. Sutural stripe reaching from elytral base up to apex. Inner discal stripe mostly connected to base, but stopping before apex. Outer discal stripe broadened subbasally, but not reaching either elytral base or apex. Epipleura yellow. Reticulation consisting of weakly but distinctly impressed polygonal meshes, with several minute punctures within them. Each elytron with a sutural, discal and lateral row of large serial setigerous punctures.

Ventral side completely yellow, somewhat darkened on the last two sternites. Reticulation consisting of small polygonal meshes. Prosternal process elongate, lanceolate, bordered laterally and produced into a long sharp point. Mesofemur and mesotibia ventrally with numerous large setigerous punctures. Metasternal wings narrow. Metacoxa with large punctures and irregular grooves laterally. Metatrochanter rounded at apex. Metafemur without setae or large punctures near posterolateral angle. Metatibia ventrally with two longitudinal rows of large punctures. Sternites with oblique grooves, anal sternite posteriorly with transverse corrugations and large punctures.

Male. Tarsomeres 1-3 of fore and middle legs weakly dilated, with bristles on ventral side. Median lobe, in lateral view, broadly attenuated and sinuous in apical third ( Fig. 3 ); in ventral view almost parallel-sided on basal two-thirds, evenly tapered on apical third, and ending in a sharp point ( Fig. 4 ). Paramere as depicted in Fig. 5 .

Female. Similar in habitus to male, but slightly larger in size. Tarsomeres of fore and middle legs not dilated.

A f f i n i t y Platambus striatus is very similar in habitus to P. lineatus , and can only be reliably distinguished by the male genitalia. The median lobe of P. striatus is broadly attenuated and sinuous in apical third, in lateral view, while the median lobe of P. lineatus is regularly narrowed to the apex.

H a b i t a t: The specimens from Moxi were collected in a small river.

D i s t r i b u t i o n: So far known only from a few localities in the mountainous areas of Sichuan and Yunnan provinces, China.

Figures

Figs 1-5: Platambus striatus (ZENG & PU): (1) habitus, specimen from Yunnan; (2) shape of pronotum; (3) median lobe in lateral view; (4) median lobe in ventral view; (5) paramere.