Willowsia trifascia sp. nov.

Figs 2−34, Table 1

Types. Holotype: adult female on slide, China, Gansu Province, Lanzhou City, Yuzhong County, Xinglongshan Mountain, 35°47′57″N, 104°04′0″E, altitude 1,900 m, 12, June, 2019, collection number: 1207, by Yitong Ma with entomological aspirator.

Paratypes: Eight adult females on slides, same data as holotype. All deposited in NTU.

Description. Body length up to 2.73 mm. Ground colour pale yellow or yellow in alcohol. Eye patches dark blue. Antennae with scattered blue pigment. Lateral margin of head with blue pigment and a “V” pattern blue stripe present on dorsal head. A pair of longitudinal blue stripes present on lateral margin of body from head to Abd. IV and a third longitudinal blue stripe along midline line from Abd. II to Abd. IV. Coxae, trochanters, femora and ventral side of body with scattered blue pigment (Figs 2−5).

Scales. Scales spinulate type (Fig. 6), present on Ant. I−II (Fig. 7), head (Fig. 8), terga, legs, ventral tube and ventral side of manubrium. Basal part of ventral side of dens also with scales (Fig. 9).

Head.Antennae 0.66−0.80 times body length; antennal segments ratio as I: II: III: IV = 1: 1.54−1.79: 1.23−1.57: 1.87−2.57. Distal part of Ant. IV with many sensory chaetae, normal ciliate chaetae and a bilobed apical bulb (Fig. 12). Distal part of Ant. III with 3−4 rods (Fig. 13). Distal part of Ant. II with 2−3 rods (Fig. 14). Dorsal cephalic chaetotaxy as 8−12 antennal (An), four median (M) and nine sutural (S) mac. Ps2 present. Interocular chaetae as p, s, t mes. Eyes 8+8, G and H smaller (Figs 8, 15). Prelabral and labral chaetae as 4/5, 5, 4, prelabral chaetae ciliate, other smooth, four labral papillae with one minute denticle each (Fig. 16). Lateral process (l. p.) of labial palp slightly curved, with tip not reaching apex of labial papilla (Fig. 17). Labial triangular chaetae usually as M1M2REL1L2, all ciliate and R 0.67−0.77 length of M1, rarely R duplicated (Fig. 18). Subapical chaeta of maxillary outer lobe thin, subequal to apical one; three smooth hairs on sublobal plate (Fig. 19).

Thorax. Th. II with three (m1, m2, m2i) mac on T1 area, seven (a5, m4, m4i, m4p, m5 and two unknown) mac on T2 area, 25−27 posterior mac, one ms and two se on each side. Th. III with 24−27, two se on each side (Fig. 20). Pseudopores on coxa I−III as 2, 3−4 (rarely 6), 1, respectively (Figs 21−23). Trochanteral organ with 51−96 smooth spiny chaetae (Fig. 24). Unguis with four inner teeth, one pair located 0.50−0.52 from base of inner edge of unguis, distal unpaired two respectively at 0.75−0.76 and 0.88−0.90 distance from base. Unguiculus acuminate and outer edge serrate. Tenent hair thick with its tip clavate, longer than inner side of unguis (Figs 10, 25).

Abdomen. Abd. IV 4.55−6.50 times as long as Abd. III along dorsal midline. Abd. I with seven (m2, m2i, m3, m4, a2, a3, a5) mac, one ms and one se, ms not inner to se. Abd. II with two (a2, a3) mac on A1 area, four (m3, m3e, m3ea, m3ep) mac on A2 area, one (m5) lateral mac and two se. Abd. III with two (a2, a3) mac on A4 area, one (m3) mac on A5 area, five (am6, pm6, p6, m7, p7) lateral mac, one ms and two se (Fig. 26). Abd. IV with 16−20 central and 18−22 lateral mac (Fig. 27). Abd. V with three se (Figs 11, 28). Ventral tube anteriorly with sacles and 14−16 ciliate chaetae on each side, three of them much larger than others (Fig. 29); posteriorly with two smooth chaetae on apical part (Fig. 30); laterally with six smooth and 17 ciliate chaetae (Fig. 31). Manubrial plate dorsally with 11−22 ciliate chaetae and 3−4 pseudopores (Fig. 32); ventrally with 34−43 ciliate chaetae on each side (Fig. 33). Uncrenulated dens 1.07−1.45 times as mucro in length. Mucro bidentate, two teeth subequal and tip of basal spine reaching subapical tooth (Fig. 34).

Ecology. Found in rotten leaf, mainly composed of Pinus tabuliformis, Quercus liaotungensis and Cotoneaster zabelii .

Etymology. Named after its three bands on dorsal body.

Remarks. The new species can be distinguished from other known Willowsia species because of its three longitudinal blue stripes on dorsal body. It is similar to W. flava Zhou, Pan & Ma, 2021 (in: Zhou et al. 2021), W. samarkandica Martynova, 1972 and W. variabilis Ma, 2016 in macrochaetotaxy of body. However, there are some differences between them, such as, colour pattern, sculpture and distribution of scales, macrochaetotaxy of head and Th. II−III, apical bulb of Ant. IV and mucro (Table 1).