Review of the genus Coelostoma of Taiwan with description of a new species (Coleoptera: Hydrophilidae) Author Liu, Hsing-Che Author Hu, Fang-Shuo Author Fikáček, Martin text Acta Entomologica Musei Nationalis Pragae 2020 2020-03-11 60 1 155 162 journal article 10.37520/aemnp.2020.008 1804-6487 3879304 16B1C03F-93E7-4BFF-B895-F846EA4CD029 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. 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 . 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 ).