Thysanarthria bifida Fikáček & Liu 2019, sp. nov.
Creators: name: Fikáček, Martin
name: Liu, Hsing-Che
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Thysanarthria
Thysanarthria bifida

description: Thysanarthria bifida sp. nov.
(Figs 6 A–E, 11)
Type material. HOLOTYPE: 1 ♂ (NHMW), THAILAND: MAE HONG SON: Mae Ping, at light, 6.i.–30.ix.1991, lgt. Malicky. PARATYPES: 6 specimens (NHMW, NMPC): same data as the holotype. CHIANG MAI: 2 spec. (NHMW): Chiang Mai, Zoo, at light, 18.–25.iv.1988, lgt. Chantaramongkol & Malicky. SONGKHLA: 3 spec. (NHMW): ʻab Ton Nga Chang WF’, 4.–5.v.1993.
Description. Body length 1.2–1.5 mm (holotype 1.3 mm), maximum body width 0.8–0.9 mm (holotype 0.9 mm). Head and labrum black, pronotum and elytra uniformly yellowish; legs reddish to yellowish. Head with weak mesh-like microsculpture on interstices; punctation sparse, each puncture bearing a seta. Eyes separated by 4.0× the width of one eye in dorsal view. Pronotum with sparse setiferous punctation similar to that on head; interstices smooth, without microsculpture. Elytra with 10 striae sharply impressed except anteromedially (near scutellar shield) where neither striae nor serial punctures are visible; intervals convex at midlength and near apex; interval punctation sparse, setiferous; interstices without microsculpture. Aedeagus 0.5 mm long. Phallobase weakly and gradually narrowing from base of parameres towards base, slightly widened basally, weakly arcuately bent in lateral view; c. 2× longer than parameres. Paremeres short, wide basally, gradually narrowing towards apex, lateral face nearly continuously arcuate, apex bluntly rounded. Median lobe wide at level of gonopore, indistinctly constricted basally of it, apex membranous, widely rounded; 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 bifida is easy to regonize by the median lobe bearing a pair of subapical membranous projections combined with the short parameres arcuately narrowing into simply rounded apices. In these characters it closely resembles T. trifida sp. nov. from which it mainly differs in smaller body size (1.2–1.5 mm in T. bifida, 1.9–2.0 mm in T. trifida), shorter and wider parameres (compare Figs 6 A–E to 6 F–J) and the membranous apex of the median lobe widely rounded (compared to the pointed one in T. trifida).
Etymology. The species name refers to the subapical pair of projections on the median lobe which make the apex of the median lobe seemingly bifid when observed under the microscope. Adjective.
Biology. Most examined specimens were collected at light, no more data are available about the biology.
Distribution. The species is so far known from three localities, two of which are situated in northwestern Thailand (provinces Mae Hong Son and Chiang Mai) and the last in the southernmost Thailand close to the border with Malaysia (province Songkhla). This indicates that the species is likely quite widely distributed but overlooked and rarely collected.
description: Published as part of 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), pp. 229-252 in Acta Entomologica Musei Nationalis Pragae 59 (1) on pages 238-240, DOI: 10.2478/aemnp-2019-0020, http://zenodo.org/record/4488918