Horniella gigas Yin and Li

Yin, Zi-Wei & Li, Li-Zhen, 2014, Revision of the Oriental genus Horniella Raffray (Coleoptera, Staphylinidae, Pselaphinae), Zootaxa 3850 (1), pp. 1-83 : 66-69

24. Horniella gigas Yin and Li , new species

Figs 40 B, 42; Map 6

Type material (1 ♂). Holotype, ♂, labeled ‘ Malaysia: Sabah, Batu , Punggul Resort env., 24.vi–01.vii.1996, 11c, vegetation debris and forest floor litter accumulated around large trees near river / Holotype [red], ♂, Horniella gigas sp. n., det. Yin & Li, 2014, MHNG’

Description. Male ( Fig. 40 B). Length 4.09 mm. Head distinctly longer than wide, HL 0.88 mm, HW 0.68 mm; anterolateral genal projections ( Fig. 42 C) weakly indicated; median sulcus between antennal tubercles short; scapes ( Fig. 42 B) lacking expansion at lateral margins; clubs ( Fig. 42 A) formed by apical three antennomeres, each distinctly elongate; venter lacking lateral spines ( Fig. 42 D). Maxillary palpomeres II greatly elongate, slightly broadened at apical 1/3. Each eye composed of about 45 facets. Pronotum longer than wide, PL 0.96 mm, PW 0.59 mm. Elytra wider than long, EL 1.02 mm, EW 1.47 mm; discal striae reaching apical 4/5 of elytral length. Protrochanters ( Fig. 42 E) each with short ventral spine, profemora ( Fig. 42 E) each with two tiny ventral denticles at base and basal 1/3, protibiae ( Fig. 42 F), mesotrochanters, mesofemora ( Fig. 42 G), and mesotibiae ( Fig. 42 H) simple; tarsomeres II extending to midlength of tarsomeres III. Abdomen large, AL 1.23 mm, AW 1.47 mm, tergite IV (first visible tergite) with median carina extending to apical 2/4 of tergal length, lacking lateral discal carinae, tergites V and VI with median carina extending to more than apical 2/3 of tergal length. Sternite IX ( Fig. 42 I) nearly oval, with well-sclerotized apical portion and less sclerotized basal portion. AeL 0.76 mm; aedeagus ( Figs 42 J–L) with relatively stout, nearly symmetric median lobe, oblique apex strongly narrowed; endophallus composed single broad and elongate sclerite with basal half membranous.

Female. Unknown.

Differential diagnosis. The H. gigas group is based on this species. The large body size (4.0 mm) and the presence of a pair of membranous parameres of the male quickly separate it from H. pilosa and H. smetanai . Both of the latter species are smaller than 3.7 mm, and the parameres are lacking on their aedeagi. The presence of parameres in H. gigas is exceptional in Horniella , and has led to an expansion of the concept of the genus.

Distribution. East Malaysia: Sabah ( Map 6 ).

Collection notes. The single males was taken from plant debris and forest floor litter that had accumulated around large trees near a river.

Etymology. The Greek word ‘ gigas ’ means ‘a giant’, referring to the large body size of the new species.

Figures

MAP 6. Distribution of Horniella species in Malaysia.

FIGURE 40. Male habitus of Horniella species. A. H. awana sp. n. B. H. gigas sp. n. Scales: 1.0 mm.

FIGURE 42. Male diagnostic features of Horniella gigas sp. n. A. Antenna. B. Scape. C. Right half of head, in dorsal view. D. Head, in lateral view. E. Protrochanter and profemur. F. Protibia. G. Mesotrochanter and mesofemur. H. Mesotibia. I. Sternite IX. J. Aedeagus, in dorsal view. K. Same, in lateral view. L. Same, in ventral view. Scales: 0.3 mm, except B, I = 0.1 mm.