Willowsia flava sp. nov.

Figs 1−25, Table 1

Types. Holotype: adult female on slide, China, Shaanxi Province, Baoji City, Taibai Mountain, Haoping Administrative Station, 34°05′12″ N, 107°42′06″ E,11, July, 2012, collection number:1102, by Yitong Ma with entomological aspirator . Paratypes: Five adult females on slides, China, Shaanxi Province, Zhouzhi County, Cuifeng Town, Qing Mountain, 34°05′39″ N, 108°02′27″ E, 14, July, 2012, collection number: 1109, by Yitong Ma. All deposited in NTU .

Description. Body length up to 2.38 mm, holotype 2.38 mm. Ground colour pale yellow or yellow in alcohol. Eye patches dark blue. Distal part of Ant. IV and base of Ant. I with blue pigment (Figs 1 & 2).

Scales. Scales spinulate type (Figs 3 & 4), present on Ant. I−II, head, terga, legs, ventral tube and ventral side of manubrium. Basal part of ventral side of dens also with scales.

Head. Antennae 0.75−0.81 times as long as body. Antennal segments ratio as I: II: III: IV = 1: 1.36−1.87: 1.36−1.58: 2.05−2.50. Distal part of Ant. IV with many smooth sensory chaetae, normal ciliate chaetae and a bilobed apical bulb (Fig. 5). Sensory organ of Ant. III as 3−4 rods (Fig. 6). Sensory organ of Ant. II as 2 rods (Fig. 7). Dorsal cephalic chaetotaxy as 9 antennal (An), 4 median (M) and 8 sutural (S) mac. Ps2 present. Interocular mes as p, r, t. Eyes 8+8, G and H smaller (Figs 8 & 9). Labral setae as 4/5, 5, 4, all slender; prelabral chaetae ciliate, other smooth, four labral papillae with one minute denticle each (Fig. 10). Lateral process of labial palp slightly curved, with tip not reaching apex of labial papilla (Fig. 11). Labial triangular chaetae as M 1 M 2 REL 1 L 2, all ciliate and R 0.63−0.73 length of M 1 (Fig. 12). Subapical chaeta of maxillary outer lobe thin, subequal to apical one; 3 smooth hairs on sublobal plate (Fig. 13).

Thorax. Th. II with 3 (m1, m2, m2i) mac on T1 area, 4 (m4, m4i, m4p, m5) mac on T2 area, 22−23 posterior mac, 2 sens on each side. Th. III with 20−21 (p2ea sometimes absent) mac, 2 sens on each side (Fig. 14). Trochanteral organ with 78−101 smooth spiny chaetae (Fig. 15). Unguis with 4 inner teeth, one pair located 0.45−0.50 from base of inner edge of unguis, distal unpaired two respectively at 0.69−0.74 and 0.84−0.90 distance from base. Unguiculus acuminate and outer edge serrate. Tenent hair thick with clavate tip, longer than inner side of unguis (Figs 16−17).

Abdomen. Abd. IV 4.00−5.23 times as long as Abd. III along dorsal midline. Abd. I with 7 (m2, m2i, m3, m4, a2, a3, a5) mac, 1 ms and 1 sens, ms not inner to sens. Abd. II with 2 (a2, a3) mac on A1 area, 4 (m3, m3e, m3ea, m3ep) mac on A2 area, 1 (m5) lateral mac and 2 sens. Abd. III with 2 (a2, a3) mac on A4 area, 1 (m3) mac on A5 area, 5 (am6, pm6, p6, m7, p7) lateral mac, 1 ms and 2 sens. Abd. IV with 16−20 central and 21−22 lateral mac. Accessory mic of bothriotrichal complexes of Abd. II−IV strongly modified or scale-like (Figs 18−19). Ventral tube anteriorly with 46−48 ciliate chaetae or scales on each side, 3 of them much larger than others (Fig. 20), posteriorly not seen wholly (Fig. 21), laterally with 5−6 smooth and 17−25 (rarely 14) ciliate chaetae (Fig. 22). Manubrial plaque dorsally with 12−21 (rarely 9) ciliate chaetae and 2−5 pseudopores (Fig. 23), ventrally with 41−47 ciliate chaetae on each side (Fig. 24). Uncrenulated dens 1.50−2.38 times as mucro in length. Mucro bidentate, two teeth subequal and tip of basal spine reaching subapical tooth (Fig. 25).

Ecology. In litter, mainly composed of leaves of maples.

Etymology. Named after its yellow (from Latin “ flavus ”) colour of terga.

Remarks. The new species can be obviously distinguished from other known Willowsia species because of its yellow colour on body. It is similar to W. samarkandica Martynova, 1972 in the number of macrochaetae on Abd. I & IV. However, their differences are great, such as, sculpture and distribution of scales, chaetotaxy of head and Th. I−II, labium, trochanteral organ, apical bulb of Ant. IV and mucro. It is somewhat similar to Chinese species W. qui Zhang, Chen & Deharveng 2011 in colour pattern, but their chaetotaxy on body, sculpture and distribution of scales, apical bulb of Ant. IV and other characters are different. It is also somewhat similar to W. pseudosocia Stach, 1965 in sculpture of scale, but a narrow stripe absent in the former and present in the latter (Table 1).