Ceresium rusticum, Yokoi, 2019

Ceresium rusticum View in CoL sp. nov.

Figs 1A- C View Fig , 14A- K View Fig

Types. Holotype Ƌ: “ ROMBLON, PHILLIPPINES”, 1979-1980, P. Witzgall et local collector leg. ( ZSM) . – Paratypes: 1 Ƌ, 1 ♀, ditto ( ZSM) .

Diagnosis. Similar to Ceresium zeylanicum White, 1855 or C. aemulator Holzschuh, 2015 . Body stocky with voluminous prothorax. Deep punctures on elytra.

Etymology. The name refers to the stocky body structure.

Description

Measurements. TL =10.4-18.0 mm; EL/EW =2.98- 3.10 (M 3.02); HW/PW =0.87-0.93 (M 0.9); PL/PW = 1.08-1.28 (M 1.18); PA/PW = 0.69-0.74 (M 0.72); PB/PW =0.86-0.91 (M 0.88).

Colour. Similar to C. zeylanicum or C. aemulator . Pronotum reddish. No significant deviation among the specimens examined.

Head. Similar to C. zeylanicum or C. aemulator ; though vertex less concave; with antennal supports more flattened.

Pronotum. Large in relation to the body, nearly 5 / 6 as wide as body; widest just before the middle, distinctly convex in profile. Sides arcuate, weakly constricted at basal 1 / 4. Disc closely, very coarsely and deeply punctured; post-median stripe narrow or obtuse with irregular boundaries; clothed similarly as the above two species. Scutellum similar.

Elytra. Almost similar to the above-mentioned species in outline, though humeri more strongly produced toward latero-basal corners. Punctures in the basal half larger and deeper, in particular near base and humeri.

Legs. Similar.

Venter. Prosternum provided densely with large and coarse punctures; clothed with pale recumbent hairs. Prosternal process narrow, truncated on apex. Mesosternum concave in middle, furnished densely with pale recumbent hairs near sides. Mesosternal process moderately broad, bi-lobed in apical third. Metasternum thickly clothed with pale, moderately long, recumbent hairs; with a nitid stripe in middle.

Abdomen clothed with pale lying hairs. 5 th visible sternite narrowed toward apex, which is widely emarginated in the middle.

Genital organs as in Fig. 14A- K View Fig . Median lobe nearly half the length of abdomen; slender and nearly bullet-shaped in dorsal view, moderately arcuate in lateral view; dorsal plate feebly arcuate on sides, dehiscent in basal 3 / 5; ventral plate a little longer than the dorsal plate, dehiscent in basal 3 / 4; median struts very narrow. Tegmen almost 9 / 10 the length of median lobe, weakly double-sinuous in profile; parameres about 2 / 5 the length of tegmen, dehiscent in apical 1 / 4, with each lobe gradually narrowed to apex which is rounded and furnished with short to medium-sized setae. Ejaculatory duct complex as Fig. 14F- H View Fig ; apical sclerites apicad dehiscent with each lobe sharply hooked. 8 th sternite widely and moderately emarginated in the apical middle, with the latero-apical corners rather sharply projected, with the latero-basal corners strongly produced; extensively thinned in the middle; clothed with short to medium hairs in the middle and longer ones on sides near apex. 8 th tergite as wide as the corresponding sternite, bell-shaped, clothed with short, stout setae near apex.

Distribution. Romblon Province, Philippines.

Comparative notes. This new species shares several external characteristics with C. zeylanicum and C. aemulator , described from Sri Lanka and Sumatra respectively.It differs from the both, firstly regarding the structure of prothorax. It is more voluminous, broader in relation to body, more convex in profile ( Figs 1B View Fig , 2), and more arcuate on sides. Secondly, punctures on elytra are larger and deeper near base and humeri.Thirdly, antennal supports are more flattened. In addition, its pronotum is much more deeply and coarsely punctured than that of C. zeylanicum .

As for genital organs, 8 th sternite of the new species is more strongly emarginated on apex than that of C. zeylanicum ( Figs 14I View Fig , 25F View Fig ) and, according to the description, less so than that of C. aemulator . Further, the 8 th tergite is apicad much more strongly narrowed than that of the former and not truncated as of the latter ( Figs 14K View Fig , 25G View Fig ). Regarding median lobe, it is bullet-shaped in dorsal view in contrast to the fusiform one of C. zeylanicum . It is also less arcuate in profile ( Figs 14A- B View Fig , 25A- B View Fig ).

Remarks. The type locality is given as above. Regarding the circumstances that all the other specimens from Romblon Province were collected on its Sibuyan Island, the type specimens were probably also collected there.