Thysanarthria hongsonensis 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 : 244

Thysanarthria hongsonensis Hebauer, 2001

( Figs 1D , 8 F–J, 11 )

Thysanarthria hongsonensis Hebauer, 2001: 398 .

Type material exmined. HOLOTYPE: ♂ ( SMNS), THAILAND: MAE HONG SON: ʻThai, N. Mae Hong Son / prov. Soppong env., 600m / 19´27´´N 98´20´´E, 28.5.- / 2.6.1999, D. Hauck leg.’

Additional material examined. THAILAND: MAE HONG SON: 1 ♂, 2 spec. ( NHMW, NMPC): Mae Ping, at light, 6.ix.1991, lgt. Malicky; 1 ♂, 1 spec. ( NHMW): same locality and collector, 24.–25.vi. 1991.

Redescription. Body length 1.5 mm, maximum body width 0.9 mm. Head and labrum black; pronotum dark brown in the middle, becoming weakly paler towards margins; elytra uniformly yellowish; legs yellowish. Head without microsculpture on interstices; punctation sparse, each puncture bearing pointed seta. Eyes separated by 3.3× the width of one eye in dorsal view. Pronotum with sparse setiferous punctation similar to that on head; interstices without microsculpture. Elytra with 10 striae sharply impressed except anteromedially (near scutellar shield) where neither striae nor serial punctures are visible; intervals weakly convex at midlength and near apex; interval punctation sparse, setiferous; interstices without microsculpture.

Aedeagus ( Figs 8 F–H) 0.5 mm long. Phallobase at the base of parameres slightly widened, but not wider than parameres combined; very slightly constricted more basally, strongly arcuate in lateral view. Parameres narrow and elongate, narrow basally, gradually narrowing into a rather acute apex, outer face of parameres sinuate. Median lobe nearly reaching apex of parameres, narrow, membranous and rounded apically, without paired subapical projections.

Differential diagnosis. The species is characterized by a tiny body size, absence of dorsal microsculpture and very characteristic aedeagus with narrow elongate parameres. In narrow parameres it may resemble T. madurensis but may be distinguished from it by sinuate lateral face of parameres (arcuate in T. madurensis ), median lobe without paired subapical projections (with the projections in T. madurensis ) and only indistinctly widened base of the phallobase (abruptly widened in T. madurensis ).

Biology. Unknown, most examined specimens were collected at light.

Distribution. So far only known from two nearby localities in northern Thailand (Mae Hong Son Province) ( 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. 8. Male genitalia of Thysanarthria species, holotypes.A–E – T. chui sp. nov.(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. hongsonensis Hebauer, 2001 (F–H – whole aedeagus in dorsal, lateral and ventral view; I–J – details of parameres and median lobe in dorsal and ventral view). K–O – T. madurensis Hebauer, 2001 (K–M – whole aedeagus in dorsal, lateral and ventral view; N–O – details of median lobe and parameres in dorsal and ventral 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.