Acrocyrtus finis Xu, Pan & Zhang 2013

Body length up to 1.2 mm. Colour pattern. Ground colour from yellow to slightly brown, a pair of dark lateral patches of Abd. III and a pair of dark postero-lateral patches of Abd. IV, slightly violet pigment distributed on antennae and gradually darker towards tip, eye patches dark (Fig. 28). Scales hyaline, oval to circular (Fig. 29), present on head, body tergites and ventral side of furcula, and absent on antennae, legs and ventral tube. Head. Ommatidia 8+8, G and H smaller than others, interocular chaetae as p, r, t, q, s, v; chaeta s smooth, chaetae p, t, q ciliate, chaetae r and v transformed to scales. Antennae 1.4–2.0 times as long as cephalic diagonal. Antennal segmental ratio as I:II:III:IV = 1:1.3–1.9:1.5–2.5:2.5–5.0. Ant. I with 3 dorsal and 3 ventral basal spiny chaetae. Ant. II with 4 basal tiny spines, 11–14 short and 1 distal rod-like S-chaetae. Ant. III organ with 2 rod-like S-chaetae. Ant. IV without apical bulb. Anterior part of head with many ciliate and long, but not claviform chaetae. Cervical with 16 spiny chaetae, all subequal in length. Prelabral and labral chaetae as 4/5, 5, 4, prelabrals ciliate and others smooth, chaetae of c-row thicker than other row chaetae; labral intrusion V-shape; labral margin with 4 papillae. Clypeus without scales. Subapical chaeta of the maxillary outer lobe subequal to apical chaeta, 3 smooth sublobal hairs on sublobular plate. Labial palp with five papillae as A–E, respectively with 0, 5, 0, 4, 4 guard chaetae; lateral process of labial palp straight, thick with tip not reaching apex of papilla E. Chaetotaxy of labial base as M1M2REL1L2, all ciliate, chaeta r shorter than others. Chaetal row along labial groove with 3 ciliate chaetae, and other postlabial chaetae ciliate. Mandible with 4+5 (left+right) teeth (Fig. 30). Leg. Coxae: I, with 5–7 ciliate mac and 2 pseudopores; II, with 6–7 ciliate mac in the anterior row, 7–9 ciliate mac in the posterior row and 3 pseudopores; III, with 6–7+3 ciliate mac and 2 pseudopores. Trochanteral organ with 10–14 smooth spiny chaetae. Unguis with 1 outer (at 1/5 distance from base), 2 lateral (at 1/4 distance from base) and 4 inner teeth (paired ones at 1/3, middle one at 2/3 and apical one at 3/4 distance from base to apical inner unguis), all tiny. Unguiculus slender and truncate with outer edge slightly serrate. Tenent hair clavate, subequal to inner margin of unguis, and slightly longer than unguiculus. Supraempodial chaeta subequal to unguiculus. Ventral tube. Anterior face with 9–15 larger ciliate chaetae; posterior face without smooth chaetae; lateral flap with 6–7 smooth and 2–3 ciliate chaetae. Furcula. Manubrial plaque with 2–3 inner, 4–6 outer ciliate chaetae and 2 pseudopores, ventral manubrium with 2+2 ciliate terminal chaetae. Dental tubercles conically pointed. Distal smooth part of dentes 1.5–2.0 times as long as mucro. Mucro bidentate, mucronal basal spine reaching subapical tooth with two accessory spinelets. Chaetotaxy. Dorsal cephalic mac as R0R1R2TS, P0 sometime absent. Body mac as 00/0100+3, S-chaetae as 21/11253, ms as 10/10100. Th. II slightly protruded over head, with 2 antero-lateral S-chaetae (ms postero-external to another one), 6 (p1–6) smooth and subequal mic and 5 anterior smooth mic of unclear homology (Fig. 31). Th. III with 1 S-chaetae external to m7, 15 (a1–4, a6, m2, m4–6 and p1–6) smooth mic, 3 (a7, m7 and m7e) mac and one other mac of unclear homology (Fig. 32). Abd. I with 1 ms external to a6, 12 (a1–3, a5–6, m2–6 and p5–6) smooth mic and 2 lateral ciliate mac of unclear homology (Fig. 33). Abd. II with 1 central S-chaetae (as), 1 (mi) ciliate and blunt mic, 14 (a2–3, a6–7, m3e, m4, m6–7, p4–5, p5p, p6–7 and el) smooth and subequal mic, 2 (Lm and Li) ciliate and slightly expanded mic, 2 (m3 and m5) ciliate mac with tip expanded, chaetae a2p and ml absent (Fig. 34). Abd. III with 1 central S-chaeta (as) and 1 lateral ms, 5 (a2, mi, ml, em and am6) ciliate mic with tip expanded, 4 (Li, Lm, Ll and a6) ciliate modified and fan-shaped mic, 9 (im, a3, a7, m3, m7, p3–5 and p7) smooth mic, 3 (pm6, m7a and p6) ciliate mac (Fig. 35). Abd. IV with 1 anterior (as) and 1 posterior (ps) short S-chaetae and 3 elongate median S-chaetae, 22 (A2–6, B2, B3, Be2, C1–4, C1p, T1, T3, T5–6, D1p, D2–3 and Fe1) smooth mic, 15 (B4–6, T7, D3p, De1, De3, E1–4, F1–3, Fe4 and Fe6) ciliate and mac, 5 (Te3, E4p, E4p2, F3p and F3p2) as mic, 4 (m, a, s and D1) ciliate and strongly fan-shaped mic, 2 (pi and pe) ciliate mic with tip expanded (Fig. 36). Abd. V with 3 S-chaetae (Fig. 37). Abd. IV:Abd. III = 2.6–4.1:1.