Coelostoma (Coelostoma) fallaciosum Orchymont, 1936

Liu, Hsing-Che, Hu, Fang-Shuo & Fikáček, Martin, 2020, Review of the genus Coelostoma of Taiwan with description of a new species (Coleoptera: Hydrophilidae), Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 155-162 : 158

Coelostoma (Coelostoma) fallaciosum Orchymont, 1936

( Figs 2A, 2H , 3D )

Coelostoma fallaciosum Orchymont, 1936: 19 .

Coelostoma fallacosum [sic!]: JIA (2005b): 148 (recorded from Taiwan

without specified locality).

Material examined. TAIWAN: TAITUNG: 1 ( TARI): Lanyu (ÊṈ), 5.iv.2011, Y.-T. Wang leg. HSINCHU: 7 spec. ( HCLC): Beipu Township [ẍẘǿ], 24.707676°N 121.060744°E, 140 m, 1.vi.2018, Hsing-Che Liu leg.; 2 ( HCLC): same locality, 9.ix.2019, Hsing-Che Liu leg. CHANGHUA: 4 ( NMNS, HCLC): Huatan Township (Kñǿ), 24.030731°N 120.545094°E, 60 m, 3.xii.2018, Hsing-Che Liu leg. TAINAN: 3 ( HCLC): Guantian District [ĎOEdz], 23.182170°N 120.307721°E, 19.i.2019, Hsing-Che Liu leg. PINGTUNG: 3 ( CNUT): Nanjenshan (ĦḺƜ), 1.xii.2018, Kai-Ying Zheng leg.

Diagnosis. Body length 4.8–5.2 mm, maximum body width 3.0– 3.2 mm. Body oval, strongly convex, dorsal surface black to dark brown. Elytra surface densely punctate, without traces of series, sutural stria reaching basal half of elytra. Labrum black with yellow edges, its front margin deeply emarginate ( Fig. 2H ). Mesofemora without dense pubescence.

Male genitalia ( Fig. 2A ): Median lobe bottle-shaped, narrowly rounded apically, strongly widened close to the base, gonopore situated subapically; parameres bent inwards in apical third, but not truncate apically.

Differential diagnosis. Coelostoma fallaciosum is similar to C. vividum Orchymont, 1936 and C. vitalisi in genitalia morphology; it can be differentiated easily by the median lobe which is bottle-shaped and has the gonopore situated subapically.

Distribution. This species is known from China (Fujian, Guangdong, Hong Kong), Indonesia, Malaysia, Nepal, Taiwan ( Fig. 4 ) and Vietnam ( ORCHYMONT 1936; HANSEN 1999; JIA 2005a; JIA et al. 2014, 2017; this paper).

Bionomics. All examined specimens were collected from the surface of soil around a pond, perched on rotting aquatic plants ( Fig. 3D ).

Figures

Fig. 2. male genitalia and front view of the head of Taiwanese Coelostoma species.A–F – genitals in dorsal view:A – C. fallaciosum Orchymont, 1936; B – C. vitalisi Orchymont, 1923; C – C. phallicum Orchymont, 1940; D – C. wui Orchymont, 1940; E – C. bhutanicum Jayaswal, 1972; F – C. stultum (Walker, 1858), specimen from Japan: Iriomote Island; G–H – front view of head with labrum: G – C. taiwanense sp. nov., paratype; H – C. fallaciosum.

Fig. 3. Habitat of Coelostoma species.A – Hsinchu County, Zhudong: habitat of C. stultum (Walker, 1858); B – Hsinchu County, Hengshan Township: habitat of C. wui Orchymont, 1940; C – Taichung City, Wufeng District:habitat of C. taiwanense sp.nov.and C. bhutanicum Jayaswal, 1972; D – Hsinchu County, Beipu Township: habitat of C. fallaciosum Orchymont, 1936; E – Yilan County, Jiaoxi Township: habitat of C. phallicum Orchymont, 1940; F – Taipei city, Neihu District: habitat of C. vitalisi Orchymont, 1923. Photos by H.-C. Liu (A–C, F), R. Matsushima (D) and F.-S. Hu (E).

Fig. 4. Map of Taiwan showing distribution of species of the Coelostoma species.