Ceresium sibuyanum, Yokoi, 2019

Ceresium sibuyanum View in CoL sp. nov.

Figs 6A- C, 18A- F

Type. Holotype Ƌ: “Espana Sibuyan Is. Romblon, Philippines ”, 1979-1980, P. Witzgall et local collector leg. ( ZSM).

Diagnosis. Prothorax elongated-cylindrical; with surface obtusely punctured. Almost universally flavus including eyes. Solely apices of femora and bases of tibiae blackish.

Etymology. The name of this new species refers to the sole location of collection and distribution.

Description

Measurements. TL = 7.8 mm; EL/EW= 3.17; HW/ PW = 0.98; PL/PW = 1.32; PA/PW = 0.8; PB/PW =0.8.

Colour. Universally flavus, including eyes. Solely apices of femora and base of tibiae dark brown to blackish.

Head. As broad as pronotum; clothed sparsely with yellowish, short, disarrayed hairs; furnished fairly densely with large, coarse punctures on frons and vertex. Frons nearly rectangular, shorter than broad; not steep. Vertex broad, provided with a deep median furrow stretching onto frons. Upper eye-lobes separated by 3 / 10 the width of occiput. Antennal supports weakly raised. Antennae distinctly longer than body, reaching elytral apices by the middle of 9 th article. Scape moderately arcuate and clavate, minutely punctured; 1.1 × longer than 3 rd and 1.65× longer than 4 th article. Articles 1-7 more or less sparsely clothed with yellowish hairs of medium length.

Pronotum. Cylindrical; almost one third longer than wide; sides sub-parallel, feebly bi-sinuate. Pronotal surface lustreless with microstructure; provided with fine though very shallow punctures; sparsely clothed with minute yellowish hairs. Disc convex; provided with a very narrow, shiny median stripe; with a pair of small semi-spherical elevations near base.

Scutellum triangular, naked and nitid.

Elytra. Sub-parallel-sided; apices almost jointly rounded; clothed regularly with yellowish, short and stout hairs.

Legs. Similar as those of C. detanii ( Yokoi 2015) .

Venter. Prosternum lustreless with microstructure; shallowly punctured; clothed with pale, short hairs near sides and with several longer flying hairs near middle. Prosternal process very narrow, compressed by fore coxae; weakly emarginated on apex. Mesosternum shiny; shallowly and obtusely punctured; clothed with pale, short, recumbent hairs near sides. Mesosternal process moderately broad, slightly concave; bi-lobed in apical third. Metasternum shiny, clothed sparsely with pale, short, recumbent hairs; more densely so near sides.

Abdomen. Clothed as metasternum; additionally furnished with several longer, flying hairs. 1 st visible sternite twice as long as 2 nd to 5 th; 5 th with apex widely rounded.

Genital organs as in Figure 18A- F View Fig . Median lobe a little more than 2 / 5 the length of abdomen; fusiform in dorsal view, weakly arcuate in profile; dorsal plate dehiscent in basal half; ventral plate a little longer than dorsal plate, apicad sharply narrowed, dehiscent in basal 3 / 4. Tegmen about 5 / 6 the length of median lobe. Paramere about 9 / 20 the length of tegmen; strongly arcuate in profile; dehiscent in the apical half; each lobe gradually narrowed toward apex, which is clothed with short to medium hairs. 8 th sternite bi-lobed like a ginkgo leaf; apicad gradually narrowed; doubly emarginated on apex; with latero-apical corners bluntly edged; clothed with medium to long setae on apex and sides. 8 th tergite distinctly wider than the corresponding sternite; bell-shaped and widely truncated on apex; clothed with medium to long setae on sides. (Ejaculatory duct complex damaged).

Distribution. Sibuyan Island, Romblon Prov. Philippines.

Comparative notes. This new species can be compared to C. detanii Yokoi,2015 and C. gracile ( Perroud, 1855) , from Bali and Sri Lanka respectively. Both of them are almost entirely yellowish in colour and provided with elongated cylindrical prothorax, whereas the prothorax of the former is shorter and that of the latter longer than of the new species. Puncture and setae on pronotum are meanwhile obviously different. The new species lacks also the remarkable maculation of C. gracile , instead provided with conspicuous black colouration on legs. As to genital organs, median lobe of C. detanii is distinctly slenderer and tegmen more strongly arcuate in profile.

It can be also compared to C. angustulum Gahan, 1906 from South India. Prothorax of the new species, is, however, clearly more strongly elongated. Both species differ also in colouration of body, eyes and legs. In addition, elytra of the new species are clothed properly with setae, though short, like the other Ceresium species, in contrast to the more obtusely setose elytra of C. angustulum .

The new species shares the similar remarkable colouration of legs with C. helleri Gressitt, 1940 from the nearby Luzon.Pronotum of the latter is, however, sub-conic (Fig. 13B) instead of cylindrical. Further, its elytra are clothed only with minute hairs and instead furnished with sporadic, long, flying hairs on pronotum, which the new species lack. In addition, venter of C. helleri is extensively naked and shiny (Fig. 13A), and its femora are more suddenly clavate with longer peduncle (Fig. 13A).

It should be added, that the new species bears certain resemblance to species of the neighbouring genus Stenodryas , on account of elongated and rather obtusely punctured pronotum. In particular, Stenodryas filipinus ( Vives, 2009) shares even the remarkable colouration of legs with the new species and with C. helleri . Other important characteristics such as body structure, length of antennae, structure of legs, integument on elytra and body indicate, however, that the new species should be indeed integrated in the genus Ceresium (see Discussion).