Holotype: ♀ on slide, China, Jiangsu Province, Nanjing, Purple Mountain, Tomb of Liao Zhongkai and his wife He Xiangning, 32.056°N, 118.830°E, altitude 38 m, 10 April 2009, Feng Zhang and Daoyuan YU leg. (# C9581). Paratypes: 1 ♂ and 4 ♀♀ on slides and 5 juveniles in alcohol, same data as holotype.

Named after the unique 5+5 central mac on Abd. II in this new species.

No eyes. Two internal sens of Ant. III organ expanded. Long smooth straight chaetae absent on antennae. Clypeal chaetae 7(5). Postlabial chaetae X, X₂ and X₄ ciliate. No “smooth” inner differentiated tibiotarsal chaetae. Tenent hairs clavate. Manubrium without smooth chaetae. Tergal ms as 1, 0|1, 0, 0, 0. Abd. II with 5+5 central mac. Abd. IV with 5+5 central and 5+5 lateral mac.

Body length up to 1.17 mm. Body pale in alcohol.

Antenna 1.69–1.80 times as long as cephalic diagonal. Antennal segments ratio as I : II : III : IV = 1 : 2.00–2.17 : 1. 82–1.90 : 3.12–3.18. Smooth spiny mic at base of antennae 3 dorsal, 3 ventral on Ant. I, 1 internal, 1 external and 1 ventral on Ant. II. Ant. II distally with 1 rod-like S-chaeta. Two internal sens of Ant. III organ expanded (Fig. 1). Long smooth straight chaetae absent on antennae.

Eyes absent. Prelabral and labral chaetae 4/ 5, 5, 4, all smooth; the three median chaetae of the row a longer than lateral ones (Fig. 2). Labral papillae absent. Clypeal chaetae 7(5), arranged in two rows; the inner two chaetae of the anterior row of four chaetae smooth in one specimen; most lateral two small chaetae absent in two specimens (Fig. 3). Dorsal cephalic chaetotaxy with four antennal (An), three median (M) and five sutural (S) mac; Gr. II with four mac (Fig. 4). Mandible teeth 4+5. Subapical chaeta of maxillary outer lobe thicker than apical one and subequal in length; three smooth sublobal hairs on maxillary outer lobe (Fig. 5). Lateral process of labial palp slightly thicker than normal chaetae, with tip beyond apex of labial papilla E (Fig. 6). Labial chaetae as mrel₁l₂, all smooth, r/m = 0.60–0.68; chaetae X, X₂ and X₄ ciliate; X₂ often absent; chaeta H₁ ciliate; H₂ smooth in one specimen and ciliate in others. Cephalic groove with 9(8) chaetae, 2(3) smooth and others ciliate (Fig. 7).

Figures 1–14. 

Sinella quinseta sp. n. 1Ant. III organ 2 labrum 3 clypeal chaetae (arrow indicates that the chaeta may be absent) 4 dorsal cephalic chaetotaxy 5 maxillary outer lobe 6 lateral process of labial palp E 7 chaetae on the ventral side of head 8 trochanteral organ 9 hind claw 10 anterior face of ventral tube 11 ventral face and lateral flap of ventral tube 12 distal part of anterior face of manubrium 13 manubrial plaque 14 mucro.

Trochanteral organ with 9–13 smooth spiny chaetae; 7–9 in arms and 2–4 between them (Fig. 8). Inner differentiated tibiotarsal chaetae ciliate with ciliations not closely appressed to axis. Tibiotarsi distally with ten chaetae in a whorl. Unguis with three inner teeth; two paired teeth unequal, outer one large. Unguiculus with a large outer tooth. Tenent hairs clavate (Fig. 9). Abd. IV 2.44–3.32 times as long as Abd. III along dorsal midline. Ventral tube anteriorly with 4–5 ciliate chaetae; one of them much larger than others (Fig. 10); posteriorly with 4 smooth chaetae; each lateral flap with 5 smooth and 2 ciliate chaetae (Fig. 11). Manubrium without smooth chaetae. Manubrium anteriorly with 5+5 ciliate chaetae in the most distal row (Fig. 12). Manubrial plaque with 2+2 pseudopores and 2+2 ciliate chaetae (Fig. 13). Distal smooth part of dens 1.34–1.85 times as long as mucro. Mucro bidentate with apical tooth longer than subapical one; basal spine long, nearly reaching tip of the apical tooth (Fig. 14).

Th. II with 3 (m1, m2, m2i) medio-medial, three (m4, m4i, m4p) medio-lateral, 20–22 posterior mac, one ms and two sens; ms inner to sens. Th. III with 29–32 mac and two lateral sens; mac a6i absent (Fig. 15). Abd. I with six (a3, m2–4, m2i, m4p) mac, one ms and one sens; sens inner to ms. Abd. II with five (a2, a3, m3, m3e, m3ep) central, one (m5) lateral mac and two sens. Abd. III with two (a2, m3) central, three (am6, pm6, p6) lateral mac and two sens; ms absent (Fig. 16). Abd. IV with five central (I, M, B4, B5, A6), five lateral mac (E2–4, E2p, F1), and approximately 13 sens; as and ps shorter than others (Fig. 17). Abd. V with three sens; chaeta p5a absent (Fig. 18).

Figures 15–18. 

Tergal chaetotaxy in S. quinseta sp. n. 15 thorax 16Abd. I‒III 17Abd. IV 18Abd. V.

In decomposing leaves along the roads.

Sinella quinseta sp. n. is characterized by blindness, ciliate postlabial chaeta H₁ and 5+5 central mac on Abd. II. It is most similar to S. yunnanica Zhang & Deharveng, 2011 in being blind, its claw structure, the lateral process of labial palp, mucro, and chaetotaxy of head, thorax and Abd. IV, but differs from it in the presence of expanded internal S-chaetae on Ant. III organ, ciliate H₂, X, X₂ and X₄ posterior to labium, 5+5 central mac on Abd. II, and the ventral tube.

Holotype: ♂ on slide, China, Jiangsu Province, Nanjing, Qixia Mountain, 32.160°N 118.960°E, altitude 114 m, 6 December 2014, Daoyuan Yu and Chunyan Qin leg. (#14NJQX4). Paratype: 4 ♀♀ on slides and 5 in alcohol, same data as holotype.

Named after the type locality.

No eyes. Two internal sens of Ant. III organ paddle-like. Long smooth straight chaetae present on antennae. Clypeal chaetae eight. Postlabial chaetae X and X_2–4 ciliate. “Smooth” inner differentiated tibiotarsal chaetae present. Tenent hairs I and II pointed or clavate, and III always clavate. Manubrium with smooth chaetae. Tergal S-microchaetae as 1, 0|1, 0, 0, 0. Abd. II with 4(3) central mac on each side. Abd. IV with 7+7 central and 6+6 lateral mac.

Body length up to 2.01 mm. Body pale in alcohol.

Antenna 2.41–2.68 times as long as cephalic diagonal. Antennal segments ratio as I : II : III : IV = 1 : 1.66–1.96 : 1. 59–1.83 : 2.44–3.00. Smooth spiny mic at base of antennae three dorsal, three ventral on Ant. I, one internal, one external and two ventral on Ant. II. Ant. II distally with two rod-like sens. Two internal sens of Ant. III organ paddle-like (Fig. 19). Ant. IV with a knobbed subapical organ. Long smooth straight chaetae at least five ventral on Ant. I, at least 13 ventral on Ant. II, and one ventral on Ant. III.

Figures 19–30. 

Sinella qixiaensis sp. n. 19Ant. III organ 20 labrum 21 clypeal chaetae 22 dorsal cephalic chaetotaxy 23 labial palp 24 chaetae on the ventral side of head 25 trochanteral organ 26 hind claw 27–29 ventral tube 27 anterior face 28 posterior face 29 lateral flap 30 male genital plate.

Eyes absent. Prelabral and labral chaetae 4/ 5, 5, 4, all smooth; median three chaetae of the row a longer than lateral ones; labral intrusion not U-shaped (Fig. 20). Labral papillae absent. Clypeal chaetae eight in number, of which three are ciliated and small (Fig. 21). Dorsal cephalic chaetotaxy with four antennal (An), three median (M) and five sutural (S) mac; Gr. II with 5–6 mac (Fig. 22). Mandible teeth 4+5. Subapical chaeta of maxillary outer lobe larger than apical one; three smooth sublobal hairs on maxillary outer lobe. Lateral process of labial palp slightly thicker than normal chaetae, with tip beyond apex of labial papilla E (Fig. 23). Labial chaetae as mrel₁l₂, all smooth, r/m=0.61–0.76; chaetae X and X_2–4 ciliate; chaeta X₃ rarely absent. Cephalic groove with 8–9 chaetae, 4(5) of them smooth and others ciliate (Fig. 24).

Trochanteral organ with approximately 24 smooth spiny chaetae; 13–15 in arms and 9–11 between them (Fig. 25). Partial inner differentiated tibiotarsal chaetae “smooth” with ciliations closely appressed to axis. Tibiotarsi distally with ten chaetae in a whorl. Unguis with three inner, one outer, and two lateral teeth; two paired inner teeth unequal, outer one large. Unguiculus with a large outer tooth. Tenent hairs I and II pointed or clavate, and III always clavate (Fig. 26). Abd. IV 3.13–4.67 as long as Abd. III along dorsal midline. Ventral tube anteriorly with 6+6 ciliate chaetae, two of them much larger than others (Fig. 27); posteriorly with 12 smooth chaetae (Fig. 28); each lateral flap with eight smooth chaetae (Fig. 29). Male genital plate with seven pairs of projections and internally with one pair of small chaetae (Fig. 30). Manubrium dorsally with about 13+13 smooth chaetae (Fig. 31); ventrally with 5+5 distal ciliate chaetae (Fig. 32). Manubrial plaque with 3+3 pseudopores and 3+3(2) ciliate chaetae. Base of dens with 2+2 smooth chaetae (Fig. 31). Distal smooth part of dens 1.04–1.12 as long as mucro. Mucro bidentate with apical tooth larger; basal spine long, with tip nearly reaching apical tooth (Fig. 33).

Figures 31–37. 

Sinella qixiaensis sp. n. 31 dorsal side of manubrium and base of dens 32 distal part of anterior face of manubrium 33 mucro 34–37 tergal chaetotaxy 34 thorax 35Abd. I‒III 36Abd. IV 37Abd. V.

Th. II with three (m1, m2, m2i) medio-medial, three (m4, m4i, m4p) medio-lateral, 22–24 posterior mac, one ms and two sens; ms inner to sens. Th. III with 30–34 mac and two lateral sens; m5i, a6i, p5, p6, m6 and m6e as mac (Fig. 34). Abd. I with seven (a2–3, m2–4, m2i, m4p) mac, one ms and one sens; sens inner to ms. Abd. II with 4(3) (m3, m3e, m3ep, m3ei) central, one (m5) lateral mac and two sens; mac m3ei only absent on one side of one specimen. Abd. III with one (m3) central, three (am6, pm6, p6) lateral mac and two sens; ms absent (Fig. 35). Abd. IV with seven central (I, M, A5–6, B4–6), six lateral mac (D3, E2–4, E2p, F1), and at least 17 sens; sens as and ps short (Fig. 36). Abd. V with 3 sens (Fig. 37).

In decomposing leaves along the roads.

Sinella qixiaensis sp. n. is characterized by blindness, the paddle-like sens of Ant. III organ and abundant smooth chaetae on the manubrium. It is most similar to Sinella insolens Chen & Christiansen, 1993 and Sinella sineocula Chen & Christiansen, 1993. It differs from the former in the presence of smooth manubrial chaetae and the absence of labial chaeta M_1s, and also differs from S. sineocula in the presence of smooth manubrial chaetae, the paddle-like sens of Ant. III organ, and the presence of mac m3ei on Abd. II.

♀ on slide and 4 in alcohol, China, Jiangsu Province, Nanjing, Lao Mountain, Long Cave, 32.051°N, 118.527°E, altitude 112 m, 10 April 2015, Daoyuan YU and Chunyan QIN leg. (# 15NJLS).

Known only from caves.

China (Jiangxi, Jiangsu).

♀ on slide and 5 in alcohol, China, Jiangsu Province, Nanjing, Lao Mountain, Longxing temple, 32.051°N, 118.527°E, altitude 112 m, 10 April 2015, Daoyuan YU and Chunyan QIN leg. (# 15NJLS).

Under stones.

China (Anhui, Jiangsu, Shaanxi).