Thaioasca contaminata Wang, Xu & Qin, sp. nov.

(Figs 1–17)

Description. Body length: Male 4.2–4.4 mm.

General color of body yellowish (Figs 1–4). Head with median black spot at apical transition from crown to face, crown short and broad, rounded anteriorly (Figs 1, 3, 4). Pronotum with yellowish-black, sinuate transverse depression laterally, mid-posteriorly black (Figs 1, 3). Fore- and hind wing subhyaline, veins distinct (Figs 5, 6). Legs whitish (Fig. 2).

2S apodemes extending to middle of segment IV (Fig. 7). Male pygofer with 10–11 tiny setae in depression of dorsal margin; apex of pygofer lobe pointed, curved upward and inward (Figs 8–12); ventral appendage developed and inflated at base, narrowed and heavily sclerotized distally, surpassing caudal margin of pygofer lobe (Figs 8–12). Subgenital plates large and fused for two-fifths of their length and surpassing pygofer lobe; basal setae (8–9) arranged in 1 or 2 rows, almost same size as macrosetae; marginal setae (8–9) setae not reaching tip of plate; macrosetae (7–8) arising at middle of plate below basal setae; feeble microsetae very sparse and shorter than macrosetae (Figs 8, 10, 13). Aedeagus slender, shaft slightly bent to right side, in lateral view wide basally, then abruptly narrowed, apex bifid in posterior view giving rise to pair of short distally directed processes (Figs 8, 9, 15, 16); gonopore close to middle of shaft, ventral. Style greatly broadened basally, distal part elongate, sinuate in ventral and lateral views, gradually tapering to bluntly rounded tip, with 4–5 fine preapical setae (Figs 8, 10, 14). Anal tube appendage extended nearly half distance to ventral margin of genital capsule, lobe-like with obtuse posteroventral edge (Figs 8–10, 17).

Holotype. Ƌ (QSBG), Thailand Chiang Mai Doi Chiang Dao WS Nature trail, 19°24.278'N 98°55.311'E, 491 m, Malaise trap, March 10–17, 2008, Songkran & Apichart leg., T3155 . Paratypes. 3ƋƋ (INHS), Thailand Nakhon Sawan Mae Wong NP Tha Ta Thai, 15°54.258'N 99°18.862'E, Malaise trap, September 1–7, 2007, Kaewkok N. & Saksit P. leg., T3597; 3ƋƋ (NWAFU), Thailand Nakhon Si Thammarat Namtok Yong NP Hill, evergreen forest, 8°13.891'N 99°47.98'E, 679 m, Pan trap, November 16–17, 2008, Paiboon leg., T4263 .

Distribution. Thailand.

Etymology. The specific epithet is derived from the Latin adjective “ contaminatus ”, contaminated, polluted, referring to the dark smudge on the crown.