Coelostoma (Lachnocoelostoma) phallicum Orchymont, 1940

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 : 158-159

Coelostoma (Lachnocoelostoma) phallicum Orchymont, 1940

( Figs 2C , 3E )

Coelostoma phallicum Orchymont, 1940: 158 .

Material examined. TAIWAN: TAITUNG: 1 ( TARI): Hsiaotianchi ( ṬXṮ), 2.iv.2016, B.-X. Guo leg. YILAN: 2 ( KMNH): ‘Yijie (áỡ)ʼ [incorrect spelling, correct name of the locality is Aijie (Ṟỡ)], Yunshan Township [DƜǿ], 12–14.ix.2000, Takashi Shimada leg.; 2, 6 ♀♀ ( NMNS): Jiaoxi Township [ḌṰǿ], Tangwei Brook Park [ȁā ặảợċă], 24°49'41.9"N 121°46'12.4"E, 22.iv.2018, F. S. Hu leg., hand collecting; 5 ( HCLC): Jiaoxi Township [ḌṰǿ], 24.824385°N 121.769800°E, 2.vii.2019, Hsing-Che Liu leg; 26 spec. ( HCLC): Luodong sports park (ůǥḋḙċă), Luodong To. [ůǥḃ], 24.6841°N, 121.7517°E, 19.i.2020, leg. F. S. Hu (near pond). HSINCHU: 1 ( HCLC): Emei Township [ŔḎǿ], 11.ix.2018,Hsing-Che Liu leg; TAIPEI: 1, 1 ♀♀ ( NMNS): NTU Farm [ȒŘRḤōö], 22.ix.2011, Y. T. Wang (ŦṪŽ).

Diagnosis. Body length 5.2–5.5 mm, maximum body width 3.2–3.3 mm. Body black. Labrum yellowish. Maxillary and labial palpi yellowish. Elytra densely punctate, without traces of series, sutural stria reaching basal half of elytra. Ventral face of pro- and mesofemora densely pubescent.

Male genitalia ( Fig. 2C ). Aedeagus 1.5 mm long, apical part of the median lobe trilobed apically, much shorter than parameres; gonopore semicircular; apical third of the paramere bends inwards.

Differential diagnosis. Coelostoma phallicum is unique among Taiwanese Coelostoma in having the median lobe trilobed apically.

Bionomics ( Fig. 3E ). The specimens of C. phallicum from Yilan were found in mud with abundant Brassica plants and from accumulations of rotten leaves in a small, artificial brook draining the water from a hot spring hotel. They were found either submerged in water or on the border of the shore zone of the stream. The specimen from Hsinchu was collected from the surface of a wet stone near the stream. The beetles were observed active at night. Distribution. This species is known from China (Guangdong, Hainan, Guangxi), Cambodia, Indonesia, Malaysia, Laos and Vietnam ( ORCHYMONT 1940, HANSEN 1999, JIA et al. 2014). New record for Taiwan ( Fig. 4 ).

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.