Thysanarthria trifida, Fikáček & Liu, 2019

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 : 250

Thysanarthria trifida sp. nov.

( Figs 6 F–J, 11 )

Type material. HOLOTYPE: ♂ ( NHMB), LAOS: BOLI KHAM XAI: 8 km NE of Ban Nape, 600 m, 1.–18.v.2001, lgt. Pacholátko. PARATYPES: 25 spec. ( NHMB, NHMW, NMPC):same data as the holotype; 1♂ ( SMNS): Ban Nape, Kaew Nua, 18.iv.1998 – 1.v.1998, lgt. E. Jendek & O. Šauša.

Description. Body length 1.9–2.0 mm (holotype 1.9 mm), maximum body width 1.0– 1.1 mm (holotype 1.0 mm). Head and labrum black; pronotum uniformly yellowish or slightly darkened centrally; elytra uniformly yellowish or with slightly darkened striae; legs yellowish. Head with weak granulate microsculpture on interstices; punctation sparse, each puncture bearing pointed seta. Eyes separated by 2.8× 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 6 F–J) 0.6 mm long. Phallobase weakly and gradually narrowing from base of parameres towards base, slightly widened basally, weakly arcuately bent in lateral view; c. 1.5× longer than parameres. Paremeres narrowly elongate, gradually narrowing towards apex, lateral face nearly continuously arcuate, apex bluntly rounded. Median lobe wide at level of gonopore, distinctly constricted basally of it, apex membranous, acutely pointed; subapical part with two triangular membranous lobes; apex reaching c. level of apex of parameres; gonopore transversely oval, situated below bases of paired projections.

Differential diagnosis. Thysanarthria trifida closely resembles T. bifida in external characters and genitalia morphology; see under the latter species for diagnostic characters. The other three species with paired subapical projections on the median lobe ( T. brincki , T. cardamona and T. madurensis ) can be differentiated from T. trifida easily by a very different shape of parameres. Species which may resemble T. trifida in the shape of the parameres ( T. championi , T. hongsonensis , T. persica ) all lack the paired projection on the median lobe.

Etymology. The species name refers to the apex of the median lobe bearing three lobes (the apex plus the pair of subapical projections). We purposely select the name sounding similar to that of T. bifida which is the most similar species to T. trifida . Adjective.

Biology. Unknown.

Distribution. So far only known from the Ban Nape area in central Laos.

Figures

Fig. 6. Male genitalia of Thysanarthria species, holotypes (A–I, K–O) and paratype (J). A–E – T.bifida 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. trifida sp. nov. (F–H – whole aedeagus of the holotype in dorsal, lateral and ventral view; I – details of parameres of the holotype; J – same of the paratype). K–O – T. ceylonensis 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.