16. Horniella kaengkrachan Yin and Li, new species

Figs 27 B, 29, 49B; Map 4

Type material (7 ♂♂, 12 ♀♀). Holotype, ♂, labeled ‘ THAILAND: Phetchaburi, Kaeng Krachan Nat. Pk, 300–400 m, 17.xi.1985, Burckhardt- Löbl / Holotype [red], ♂, Horniella kaengkrachan sp. n., det. Yin & Li, 2014, MHNG’ . Paratypes: 2 ♀♀, same data as the holotype; 3 ♂♂, 8 ♀♀, same data, except ‘ 450 m, 18.xi.1985 ’; 3 ♂♂, 2 ♀♀, same data, except ‘ 19.xi.1985 ’. All paratypes are housed in MHNG, and each bears a yellow type label similar to that of the holotype except ‘ PARATYPE ♂ (or ♀)’.

Description. Male (Fig. 27 B). Length 2.96–3.21 mm. Head about as long as wide, HL 0.64–0.67 mm, HW 0.64– 0.61 mm; anterolateral genal projections (Fig. 29 C) distinct, anterior margins roundly concave; median sulcus between antennal tubercles short; scapes (Fig. 29 B) angularly expanded at anterolateral margins; clubs (Fig. 29 A) loosely formed by apical three moderately enlarged antennomeres; venter with pair of short, relatively thick lateral spines (Fig. 29 D). Maxillary palpomeres II stout, widest near middle. Each eye composed of about 35–45 facets. Pronotum as long as wide, PL 0.59–0.64 mm, PW 0.58–0.61 mm. Elytra wider than long, EL 0.79–0.84 mm, EW 1.19–1.29 mm; shallow discal striae reaching apical 3/4 of elytral length. Protrochanters and profemora (Fig. 29 E) each with one long ventral spine, protibiae (Fig. 29 F) with small triangular spur; mesotrochanters (Fig. 29 G) with extremely short, apically blunt ventral spine, mesofemora and mesotibiae (Fig. 29 H) simple; tarsomeres II normal, not extending to beneath tarsomeres III. Abdomen large, AL 0.94–1.06 mm, AW 1.22–1.23 mm, tergite IV (first visible tergite) with distinct median carina extending to apical 3/4 of tergal length, lacking lateral discal carinae, tergite V lacking median carina. Sternite IX (Fig. 29 I) with well-sclerotized apical half, and membranous narrowed basal half. AeL 0.61 mm; aedeagus (Figs 29 J–L) with nearly symmetric median lobe, apex obliquely truncate; endophallus complicated, composed of four major sclerites.

Female. Similar to male in general appearance; each eye composed of about 25 facets; profemora each with two ventral spines near base, lacking spine or spur on mid and hind legs. BL 2.79–3.01 mm, HL 0.62–0.65 mm, HW 0.53–0.58 mm, PL 0.56–0.61 mm, PW 0.56–0.59 mm, EL 0.73–0.74 mm, EW 1.06–1.16 mm, AL 0.87–1.02 mm, AW 1.19–1.22 mm. Genital complex (Fig. 49 B) weakly sclerotized, composed of broadly transverse, platelike apical sclerite, and elongate membranous basal portion.

Differential diagnosis. This species is placed as a member of the H. burckhardti group. As discussed above, males share with H. intricata the roundly concave anterior margins of the apicolateral genal projections, the short and apically blunt ventral spine on the mesotrochanters, the nearly symmetric aedeagal median lobe with an obliquely truncate apex, and complicated structure of the aedeagal endophallus. These two species are easily separated by the weakly-developed expansion on the lateral margins of the scapes, the presence of a triangular apical spur on the mesotibiae in H. kaengkrachan, which also has a completely different form of the aedeagal endophallus.

Distribution. Thailand: Phetchaburi (Map 4).

Collection notes. Adults were collected from leaf litter samples by sifting and use of Winkler-Moczarski extractors.

Etymology. The new species is named after its type locality, the Kaeng Krachan National Park.