Six new species of Horniella Raffray from the Oriental region (Coleoptera, Staphylinidae, Pselaphinae) Author Zhang, Wen-Xuan Laboratory of Systematic Entomology, College of Life Sciences, Shanghai Normal University, 100 Guilin Road, Xuhui District, Shanghai 200234, China Author Hu, Fang-Shuo https://orcid.org/0000-0003-1269-8904 Department of Entomology, National Chung Hsing University 145 Xingda Rd., South District, Taichung City 402, Taiwan, China Author Yin, Zi-Wei https://orcid.org/0000-0001-6659-9448 Laboratory of Systematic Entomology, College of Life Sciences, Shanghai Normal University, 100 Guilin Road, Xuhui District, Shanghai 200234, China pselaphinae@gmail.com text ZooKeys 2021 2021-06-04 1042 1 22 http://dx.doi.org/10.3897/zookeys.1042.66576 journal article http://dx.doi.org/10.3897/zookeys.1042.66576 1313-2970-1042-1 B0B0F76E89504A0AB45D701730486B56 0930CA7A3EDB571AA10D026EF39B1739 Horniella sabahensis Zhang & Yin sp. nov. Figures 7A , 8 Type material. Holotype : East Malaysia : ♂, 'Borneo: Sabah, Batu Punggul Resort, primary forest, 24.vi.-1.vii.96, Kodada lgt. / vegetation debris and forest floor litter accumulated around large trees near river.' (MHNG). Figure 7. Dorsal habitus of Horniella species A H. sabahensis sp. nov. B H. taiwanensis sp. nov. Scale bars: 1 mm. Diagnosis. Male. Head longer than wide, anterolateral genal projections weakly developed, anterior margin of projection oblique; scape lacking expansion at lateral margin, antennomeres 9-11 moderately enlarged, forming distinct club. Pronotum rounded at lateral margins. Profemur with two tiny ventral spines near base; metatibia with preapical triangular denticle. Tergite 1 (IV) with median carina extending posteriorly for approximately 3/4 of tergal length, lacking discal carinae, tergite 2 (V) with short median carina. Aedeagus with slightly asymmetric median lobe, apical portion of median lobe narrowed, apex truncate in dorso-ventral view; endophallus lacking sclerite, composed of elongate membranous structure with many small denticles. Description. Male. Body reddish-brown, length 3.41 mm. Head (Fig. 8A ) longer than wide, HL 0.68 mm, HW 0.59 mm; anterolateral genal projection weakly developed, anterior margin of projection oblique; antenna 1.96 mm long, scape lacking expansion at lateral margin, antennomeres 2-8 slightly elongate or moniliform, distinct club formed by apical three enlarged antennomeres, antennomere 11 largest, slightly shorter than antennomeres 9 and 10 combined; indistinct lateral postantennal pits present; eyes prominent, each composed of approximately 40 large facets, usual area of ocular canthus only slightly prominent (Fig. 8B ). Figure 8. Diagnostic characters of Horniella sabahensis sp. nov. A left half of head, in dorsal view B head, in lateral view C protrochanter and profemur D protibia E mesotrochanter and mesofemur F mesotibia G metatibia H-J aedeagus, in dorsal ( H ), lateral ( I ), and ventral ( J ) view. Scale bars: 0.2 mm ( A, B, H-J ); 0.3 mm ( C-G ). Pronotum distinctly longer than wide, PL 0.71 mm, PW 0.6 mm; widest at middle; lateral margins rounded; disc moderately convex, finely punctate, with distinct median antebasal and lateral antebasal foveae connected by complete transverse antebasal sulcus. Elytra much wider than long, EL 0.77 mm, EW 1.2 mm; each elytron with two large, setose basal foveae; discal striae extending from outer basal foveae to apical 2/3 of elytral length. Legs elongate; protrochanter (Fig. 8C ) simple, profemur (Fig. 8C ) with two tiny ventral spines at base, protibia (Fig. 8D ) simple; mesotrochanter, mesofemur (Fig. 8E ) and mesotibia (Fig. 8F ) simple; metatibia (Fig. 8G ) with distinct apical triangular denticle. Abdomen slightly longer than broad, broadest at lateral margins of tergite 1 (IV), AL 1.25 mm, AW 1.16 mm; tergite 1 (IV) largest, slightly shorter than tergites 2 and 3 (V and VI) combined, with median carina extending to near basal 3/4 of tergal length, lacking discal carinae, tergite 2 (V) with median carina extending to near basal 1/4 of tergal length, tergites 2-4 (V-VII) each with small basolateral foveae. Sternite 2 (IV) with broad basal sulcus, lacking mediobasal foveae, basolateral foveae developed as large cuticular pockets, with two pairs of antebasal nodules, sternites 3-5 (V-VII) with basolateral foveae, one median and two lateral nodules, sternite 7 (IX) nearly oval, with well-sclerotized apical half and less sclerotized basal half. Aedeagus (Fig. 8H-J ) 0.57 mm long, with slightly asymmetric median lobe, apical part of median lobe narrowed, apex broadly truncate in dorso-ventral view; endophallus lacking strongly sclerotized structures, composed of broad, elongate membrane with numerous small denticles. Female. Unknown. Comparative notes. Horniella sabahensis sp. nov. is placed as a member of the H. hirtella group. Males of this species share with H. prolixo Yin & Li from Thailand the weakly developed anterolateral genal projections, lack of an expansion at the lateral margin of the scape, and a moderately expanded preapical portion of the metatibia. They can be best separated by the larger body size (3.41 mm vs 2.95-3.02 mm), tergite V with a short median carina (lacking in H. prolixo ), as well as the much narrower apex of the aedeagus of the new species. Distribution. East Malaysia: Sabah. Etymology. The new species is named after its type locality, Sabah, East Malaysia.