Holotype. 1♀ on slide, China, Xizang autonomous region, Lhasa city, Chengguan District, Gesan flower park, 29°39'59.5764"N, 91°7'18.3828"E, 3634±5 m asl, sample number 4692, collected by Z-X Pan, C-C Si, and F-H Jia, 3-VIII-2019. Paratypes. 7♀adults, 1 first and 1 second instar larva on slides and 5 adults in ethanol, same data as holotype.

Size. Body length up to 1.62 mm. Colour pattern. Ground colour yellow-white in ethanol. Eye patches dark blue. Antennae gradually darker from Ant. I to Ant. IV. A dark narrow transverse band between basal antennae. Lateral Th. II–III with longitudinal bands, and dorsal Th. III with central transverse uninterrupted dark band. Coxa with dark pigment. Dorsal Abd. II and Abd. IV with central irregular dark bands. Dorsal Abd. III and Abd. V from anterior to posterior margin with dark transverse bands, and Abd. III with two lateral unpigmented areas. Dorsal Abd. IV with two middle and posterior transverse bands, the central one interrupted by a middle line (Figs 4, 5). Ventral side of body and VT pale white, without pigment (Fig. 6). Subadults with the same colour pattern as adults, but paler (Fig. 7).

Head. Eyes 8+8, G and H smaller than others and always difficult to observe under light microscope; three chaetae (p, r, and t) within eye patches, with p largest (Fig. 10). Antenna 1.56–2.16 times as long as cephalic diagonal; antennal segments ratio as I:II:III:IV = 1:1.11–1.72: 1.15–1.76:1.97–2.73. Ant. I base with seven (rarely as three) dorsal smooth mic and four ventral (Fig. 11). Ant. II base with five smooth mic (Fig. 12). Ant. III organ with two rod-like and three short guard S-chaetae (Fig. 13). Apical bulb on Ant. IV bilobed (Fig. 14). Prelabral and labral chaetae as 4/5, 5, 4, all smooth; without labral papillae. Clypeus with 16 (6/7/3) chaetae in three lines (Fig. 15). Cephalic chaetotaxy on dorsal side shown in Fig. 10, An series with four (An1–3, An3a), A series with four (A0, A1, A3, A5), M series with four (M1–4), S series with eight (S0–5, S4i, S5i), P series with 18 (Ps2, Ps5, Pi1, Pa1–5, Pm1–3, Pm5, Pp1–3, Pp5, Pp1e, Pp3e) mac. Chaetae on labium basis as MReL₁L₂, chaeta e smooth; postlabial chaetae not expanded, with G_1–4, H_1–4, X₂, X₃, X all ciliate, X₄ unclear; five proximal chaetae (Fig. 16). Five papillae A–E on labial palp with 0, 5, 0, 4, 3 guard chaetae, respectively; l.p. normal, with tip beyond apex of papilla E (Fig. 17). Maxillary outer lobe with single apical chaeta, one subapical chaeta, and three sublobal hairs on sublobal plate; subapical chaeta subequal in length to apical one (Fig. 18). Mandible with 4/5 apical teeth and basal strong molar plate (Fig. 19)

Figures 10–19. 

Adults of Homidia breviseta Pan sp. nov. 10 cephalic chaetotaxy on dorsal side 11 base of Ant. I 12 base of Ant. II 13 Ant. III organ 14 distal part of Ant. IV 15 clypeal chaetotaxy 16 labium 17 labial papilla E 18 maxillary outer lobe 19 right mandible. Scale bars: 50 μm

Thorax. Complete body sens from Th. II to Abd. IV as 2, 2/1, 2, 2, 28 (26 elongate and two of normal length), 3, ms as 1, 0/1, 0, 1, 0, 0. Th. II with seven medio-medial (m1, m1i, m2, m2i and m2i2 and other two additional mes; arrow shown in Fig. 20), three medio-sublateral (m4, m4i and m4i2) mac and three S-chaetae (ms antero-external to sens); posterior with 39–43 mac; p6 as mic. Th. III with 42–47 mac and two sens; p5, p6 and m6 as mac, p4 as mic (Fig. 20). Coxal macrochaetal formula as 3 (two pseudopores)/4+1, 3 (three pseudopores)/ 4+2 (one pseudopore) mac (Fig. 21). Trochanteral organ with 31–40 smooth chaetae, six or seven in ventral line, and five or six in posterior line (Fig. 22). Inner side of tibiotarsus with slightly ciliated chaetae. Tenent hairs clavate, slightly shorter than inner edge of unguis in length. Unguis with four inner and two lateral teeth. Unguiculus lanceolate with outer edge smooth (Fig. 23).

Figures 20–23. 

Adults of Homidia breviseta Pan, sp. nov. 20 chaetotaxy of Th. II–III 21 coxae (a fore leg b mid leg c hind leg) 22 trochanteral organ 23 distal part of tibiotarsus and claw of hind leg. Scale bars: 50 μm.

Abdomen. Abd. IV 5–8 times longer than Abd. III along the dorsal axis. Abd. I with 14 mac (a1–3, a5, a1a, a1i, a2i, m2–5, m2i, m4i, m4p) and two S-chaetae (ms antero-external to sens). Abd. II with seven central (a2, a3, m3, m3e, m3ea and m3ep, m3ei) and one lateral (m5) mac. Abd. III with two central (a2 and m3) and two lateral (am6, pm6, p6 and m7) mac, two sens and one ms (Fig. 24). Abd. IV with 26 elongated and two normal length sens, and 6–9 mac arranged in anterior transversal line; postero-central area with seven mac (A4–6, B4–6, Ae6; one individual examined with Ae4 and Ae7), bothriotricha short and no more than two times as long as normal ciliate chaetae (Figs 9, 25). Abd. V with three sens, the middle one posterior to m3, the lateral one between chaetae a5 and m5; a1 as mic; a3, m3, m5, a5, m5, and a6 as mac (Fig. 25). Anterior face of VT with many ciliate chaetae, 3+3 of them as mac, the line connecting proximal (Pr) and external-distal (Ed) mac obliquely to median furrow (Fig. 26); lateral flap with 5–7 smooth and 10–17 ciliate chaetae on each side (Fig. 27); apical posterior face as five (2+1+2) smooth chaetae (two specimens examined here with four smooth chaetae) (Fig. 28). Manubrial plate with three pseudopores and eight or nine ciliate chaetae (Fig. 29). Dens with 23–33 inner spines, distal smooth part slightly shorter than mucro (only basal part shown in Fig. 30). Mucro bidentate with subapical tooth larger than apical one; basal spine short, with tip reaching subapical tooth. Tenaculum with 4+4 teeth and single large, multi-laterally, basally ciliate chaeta (Fig. 31).

Figures 24–31. 

adults of Homidia breviseta Pan, sp. nov. 24 chaetotaxy of Abd. I–III 25 chaetotaxy of Abd. IV–V 26 anterior face of VT 27 lateral flap of VT 28 posterior face of VT 29 manubrial plaque 30 basal part of dens 31 tenaculum. Scale bars: 50 μm.

Size. Body length up to 0.59 mm. Colour pattern. Ground colour whitish, only eye patches dark blue, others all without pigment (Fig. 8).

Body. Complete tergal sens from Th. II to Abd. V as 2, 2/1, 2, 2, 28, 3, ms as 1, 0/1, 0, 1, 0, 0. Cephalic chaetotaxy on dorsal side with three (An1–3), six (A0–5), four (M1–4), six (S0–5) mac of An, A, M, S series, respectively; eyes 8+8, eye patches with three chaetae (p, r, and t; p largest). Labium with three proximal chaetae, four chaetae (M, e, A and B) in basomedial field and five chaetae (C, D, F, L₁ and L₂) in basolateral field, chaetae M, L₁ and L₂ ciliate, and others smooth; posterior area of labium with two ciliate mac along median furrow (Fig. 33). Th. II with seven anterior (a1–7), six median (m1–2, m4–7), and six posterior (p1–6) primary chaetae arranged in three rows; chaetae a7, m2, m5, m7, and p4, p6 as mic, others as mac, and with three S-chaetae (ms antero-external to sens). Th. III with seven anterior (a1–7), five median (m1, m4–7), and six posterior (p1–6) primary chaetae arranged in three rows and two S-chaetae; chaetae a4, a7, m1, m4, m5, m7, and p4–6 as mic, others as mac. Abd. I with five anterior (a1–3, a5–6), five median (m2–6), and two posterior (p5–6) primary chaetae arranged in three rows and two S-chaetae (ms antero-external to sens); chaetae m2–m4 as mac, others as mic. Abd. II with six anterior (a1–3, a5–7), six median (m2–7), and four posterior (p4–7) primary chaetae arranged in three rows, an additional chaeta external to p7 and two S-chaetae; chaetae m3 and m5 as mac, a5 and m2 as bothriotricha, others as mic. Abd. III with six anterior (a1–3, a5–7), seven median (m2–5, am6, pm6, m7), and four posterior (p4–7) primary chaetae arranged in three rows, five additional chaetae in lateral region, and three S-chaetae (one ms and two sens); chaeta m3 as mac, m2, a5, and m5 as bothriotricha, others as mic (Fig. 34). Abd. IV with five (A1–4, A6), six (B1–6), four (C1–4), seven (T1–7), three (D1–3), three (E1–3), and three (F1–3) primary ciliate chaetae arranged in seven longitudinal lines, one side with an additional ciliate chaeta between C2 and C3 (shown by arrow in Fig. 35), and 26 elongated and two normal sens; T2 and T4 as bothriotricha. Abd. V with 13 primary chaetae (m2, m3 and m5 as mac; others as mic) and three sens, the median sens posterior to m3 (Fig. 35).

Figures 32–39. 

The first instar larva of Homidia breviseta Pan, sp. nov. 32 chaetotaxy of Ant. I–III 33 labium 34 chaetotaxy of Th. II–Abd. III 35 chaetotaxy of Abd. IV–V 36 ventral tube 37 manubrium 38 dens 39 tenaculum. Scale bars: 50 μm.

Appendages. Ant. I with 11 ciliate chaetae arranged in one whole and one basal smooth chaeta. Ant. II with 25 ciliate chaetae, arranged in three wholes (from basis to apex as 8/8/9), basis without smooth spiny chaetae. Ant. III with 37 ciliate chaetae arranged in four wholes (11/12/13/2) and five S-chaetae (Ant. III organ) (Fig. 32). Primary chaetae on Ant. IV unclear. Ventral tube with two smooth chaetae on the posterior face and on each lateral flap, anterior face without chaetae (Fig. 36). Manubrium with 46 ciliate chaetae (Fig. 37); dens with numerous ciliate chaetae, without inner dental spines; chaetae bs2, bs1, pi unclear; mucro with subapical tooth larger than apical one, basal spine absent (Fig. 38). Tenaculum with 4+4 teeth and without basal chaetae (Fig. 39). Four segments of fore, mid and hind leg with numerous chaetae, subcoxae with 1, 2, 3 ciliate chaetae, coxae with 1, 1, 2 ciliate chaetae, pseudopore(s) unclear; trochanters with six (one smooth), six (two smooth), five (one smooth and one spine like) chaetae; femurs with 17 (three smooth), 17 (smooth chaetae unclear), 17 (two smooth) chaetae; tibiotarsus with 39 (10/8/8/8/4 ciliate and one tenent hair), 41 (10/8/8/8/6 ciliate and one tenent hair), 48 (10/7/9/9/9/2, one tenent hair and one inner smooth chaetae) ciliate chaetae (Figs 40–42).

Figures 40–42. 

Left legs of the first instar larva of Homidia breviseta Pan, sp. nov. 40 fore leg 41 mid leg 42 hind leg. Scale bars: 50 μm.

Colour pattern. Ground colour whitish; eye patches dark blue. The colour pattern of the second instar larva is similar to adult, but slighter.

The chaetotaxy of the second instar larva is more complex than first instar, and several primary chaetae with secondary chaetae present in the second instar (Figs 43–54). The detailed comparison between these two instars are tabulated in Table 3.

Figures 43–45. 

The second instar larva of Homidia breviseta Pan, sp. nov. 43 cephalic chaetotaxy 44 labium 45 chaetotaxy of Th. II–Abd. III. Scale bars: 50 μm.

All stages were found in leaf litter of the Family Rosaceae.

Figures 46–51. 

The second instar larva of Homidia breviseta Pan, sp. nov. 46 chaetotaxy of Abd. IV 47 chaetotaxy of Abd. V 48 ventral tube 49 manubrium 50 dens 51 tenaculum. Scale bars: 50 μm.

The specific epithet refers to the very short chaeta bothriotricha on dorsal Abd. II–IV (brevi and seta).

Figures 52–54. 

Legs of the second instar larva of Homidia breviseta Pan, sp. nov. 52 fore leg 53 mid leg 54 hind leg. Scale bars: 50 μm.

This new species is mostly similar to Homidia similis Szeptycki, 1973 in having Th. III, Abd. III, and the middle and posterior of Abd. IV and Abd. V with transverse bands; in the chaetotaxy of the labium, head, Th. III, and Abd. II–III; and smooth chaetae on posterior face (five) and lateral flap (six) of VT. However, the new species can be differentiated from H. similis by the uninterrupted band on Th. III (interrupted by a central line in latter), a broad band from the anterior to posterior margin of Abd. III (anterior margin not pigmented in the latter), 14 mac on Abd. I (nine in the latter), and seven posterior central mac on Abd. IV (eight in the latter). Also, the new species is similar to H. bilineata Lee & Park, 1984 and Homidia huashanensis Jia et al., 2005 in having mac on the dorsal head, Th. II–III, and Abd. II and chaetal formula on labium; however, they can be discriminated by colour pattern, chaetotaxy on Abd. I and posterior central Abd. IV. A detailed comparison of these four similar species is given in Table 2.

This species is the second species of genus Homidia described from Xizang, and it can be easily distinguished from the first new species recorded from this region (H. tibetensis Chen & Zhong, 1998) by the colour pattern (dorsal central pigments on Th. III and Abd. III in the new species, absent in H. tibetensis), chaetotaxy on the labial triangle (M2 absent in the new species, but present in H. tibetensis), Abd. I (14 mac in the new species, and 11 in H. tibetensis), and posterior part of Abd. IV (seven in new species and only two in H. tibetensis).