Thysanarthria bengalensis Hebauer, 2001

Fikáček, Martin & Liu, Hsing-Che, 2019, A review of Thysanarthria with description of seven new species and comments on its relationship to Chaetarthria (Hydrophilidae: Chaetarthriini), Acta Entomologica Musei Nationalis Pragae 59 (1), pp. 229-252 : 238

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).

Figures

Fig. 1. Habitus of the Thysanarthria species and related Old Word Chaetarthriini.A – Thysanarthria bengalensis Hebauer, 2001, holotype; B – T. persica sp. nov., paratype; C – T. siamensis Hebauer, 2001, holotype; D – T. hongsonensis Hebauer, 2001, holotype; E – European Chaetarthria: C. seminulum (Herbst, 1797); F – large Old World Chaetarthria: C. nigerrima (Blackburn, 1891).

Fig. 5. Male genitalia of Thysanarthria species, holotypes.A–E – T.brincki Hebauer, 2001 (A–C – whole aedeagus in dorsal, lateral and ventral view; D–E – detail of median lobe and parameres in dorsal and ventral view); F–J – T. cardamona sp. nov. (F–H – whole aedeagus in dorsal, lateral and ventral view; I–J – detail of median lobe and parameres in dorsal and ventral view); K–M – T. bengalensis Hebauer, 2001 (K – photo of the aedeagus before re-mounting; L – whole aedeagus in ventral view; M – whole aedeagus in lateral view).

Fig. 11. Distribution of Thysanarthria and American Chaetarthria in Asia (A–B) and Near East (C), and examples of habitats of Thysanarthria (D–F). Localities: D – India, Madhya Pradesh, Bhadhua Chora stream ca. 10 km E of Matkuli Jhir, habitat of T. ceylonensis Hebauer, 2001; E – Republic of South Africa, Western Cape, 8 km NEE of Stanford, habitat of T. atriceps (Régimber, 1903), collecting spot marked by an arrow; F–G – Taiwan, Wufeng distr., 4.3 km SEE of Chaoyang University of Technology, habitat of T. chui sp. nov. (G – detail of sandy shore with one alive beetle). Photo D by M. Jäch, photo E by M. Fikáček, F–G by H.-C. Liu.