A review of Thysanarthria with description of seven new species and comments on its relationship to Chaetarthria (Hydrophilidae: Chaetarthriini) Author Fikáček, Martin Department of Entomology, National Museum, Cirkusová 1740, CZ- 19100 Praha 9 – Horní Počernice, Czech Republic & Department of Zoology, Faculty of Science, Charles University, Viničná 7, CZ- 12844 Praha 2, Czech Republic mfikacek@gmail.com Author Liu, Hsing-Che Department of Environmental Engineering and Management, Chaoyang University of Technology, No. 168, Jifeng E. Rd., Taichung City 413, Taiwan td965771@gmail.com text Acta Entomologica Musei Nationalis Pragae 2019 2019-06-20 59 1 229 252 journal article 8143 10.2478/aemnp-2019-0020 a03ecce2-b526-4f94-aa65-620016956099 1804-6487 4488918 9F309FCC-A2ED-47B9-BC37-D0C4A3B482E5 Thysanarthria bengalensis Hebauer, 2001 ( Figs 1A , 5 K–M, 11 ) Thysanarthria bengalensis Hebauer, 2001: 395 . Type material examined. HOLOTYPE : ♂ ( SMNS ), ʻEAST PAKISTAN / Dinajpur / X-1969 Barbe // HOLOTYPUS / Thysanarthria / bengalensis sp.n. / des. F. Hebauerʼ . Redescription. Body length 2.2 mm , maximum body width 1.3 mm . Head and labrum black, pronotum and elytra uniformly yellowish; legs reddish to yellowish. Head with strong mesh-like microsculpture on interstices; punctation sparse, each puncture bearing pointed seta. Eyes separated by 3.0× the width of one eye in dorsal view. Pronotum with sparse setiferous punctation similar to that on head; interstices with strong mesh-like microsculpture. Elytra with 10 striae, sharply impressed except basally; intervals distintcly convex at midlength and near apex; interval punctation sparse, setiferous; interstices with very faint mesh-like microsculpture. Aedeagus c. 0.6 mm long. Phallobase wide at base of parameres, strongly constricted at midlength into a very narrowly tubular basal part, bent in nearly right angle in lateral view close to parameral base, c. 1.3× longer than parameres. Paremeres wide, c. of same width throughout, arcuately bent, cut off apically and projecting into a small denticle apicomesally. Median lobe not examined as it is absent (damaged) in the holotype . Differential diagnosis. Thysanarthria bengalensis is the largest species of the genus and differs from all other species in all elytral series (including the mesal ones) nearly reaching the base of the elytra. In the presence of strong microsculpture on the head and pronotum it resembles T. brincki and T. saurahana , from which it can be easily distinguished by the morphology of male genitalia. The form of the phallobase (extremely constricted in dorsal/ ventral views, and bent in nearly right angle in the lateral view ‒ Fig. 5M ) is also unique for this species, and makes it easy to distinguish. Biology. Unknown. Distribution. Only known from the type locality in northern Bangladesh ( HEBAUER 2001 ).