Sinella liuae sp. nov.

Figs 1, 4‒23, Table 1

Types. Holotype: female on slide, China: Guizhou Province: Qiandongnan: Shuiwei town: Changping village: Jiangjun cave, 109.016°E, 27.433°N, altitude 550 m, 28.vi.2014, Mingyi TIAN, Weixin LIU, Haowen YIN, Sunbin HUANG and Xinhui WANG leg . (collection # 15cave1). Paratypes: female on slide and 1 in alcohol, same data as holotype. All material deposited in NJAU .

Description. Body length up to 2.1 mm. Body whitish in alcohol (Fig. 1).

Antennae 3.3‒3.6 times as long as cephalic diagonal. Antennal segments ratio as I: II: III: IV = 1: 1.8‒2.3: 2.0‒2.4: 3.8‒4.1. Smooth spiny mic at base of antennae: 3 dorsal, 3 ventral on Ant. I, 1 internal, 1 external and 2 ventral on Ant. II. Long smooth straight chaetae: 3 ventral on Ant. I and 4 ventral on Ant. II. Distal Ant. II with 1 paddle-like S-chaeta. Two internal S-chaetae of Ant. III organ paddle-like but not expanded; chaeta 8 dagger-like (Fig. 4). Ant. IV with a knobbed subapical organ (Fig. 5).

Eyes absent. Prelabral and labral chaetae 4/ 5, 5, 4, all smooth; median three chaetae of the first row longer than lateral ones. Eight clypeal chaetae arranged in three rows; three of them ciliate and smaller than others (Fig. 6). Dorsal cephalic chaetotaxy with 4 antennal (An), 3 median (M) and 8 sutural (S) mac; Gr. II with 4 mac (Fig. 7).

Mandibles with 4+5 (4 left, 5 right) large apical teeth. Subapical chaeta of maxillary outer lobe slightly thicker than apical one; 3 smooth sublobal hairs on maxillary outer lobe (Fig. 8). Labial palp with 0, 5, 0, 4, 4 guard chaetae on papillae A‒E, respectively; lateral process of labial palp slightly thicker than normal chaetae, with tip beyond apex of labial papilla (Fig. 9). Labial chaetae as mrel1l2, all smooth, ratio of r to m 0.6‒0.7; chaetae X, X2 and X4 ciliate; chaeta X3 usually smooth but ciliate on one side of one specimen. Chaetae along cephalic groove 8‒9, four of them smooth (Fig. 10).

Trochanteral organ with 22–31 smooth spiny chaetae; 10–15 in arms and 11‒16 between them (Fig. 11). Partial inner differentiated tibiotarsal chaetae “smooth” with ciliations closely appressed to axis. Tibiotarsi distally with 10 chaetae in a whorl. Unguis with 3 inner teeth; 2 paired teeth unequal, outer one large; distal unpaired tooth minute. Unguiculus truncate or swollen with a large outer tooth. All tenent hairs smooth and pointed (Figs 12–14). Abd. IV 5.6‒5.7 times as long as Abd. III along dorsal midline. Ventral tube anteriorly with at least 3+3 ciliate large chaetae; posteriorly with 4 apical smooth and about 20 proximal ciliate chaetae (Fig. 15); each lateral flap with 8 smooth chaetae (Fig. 16). Manubrial smooth chaetae unclear. Distal part of manubrium ventrally with 6+6 ciliate chaetae (Fig. 17). Manubrial plaque with 3 (rarely 2) pseudopores and 3 (rarely 4) ciliate chaetae (Fig. 18). Distal smooth part of dens 0.7 times as long as mucro. Mucro bidentate with apical tooth larger than basal one; basal spine long with tip nearly reaching apical tooth (Fig. 19).

Th. II with 3(4) (m1, m2, m 2i) medio-medial, 3(2) (m4, m 4i, m4p) medio-lateral, 21‒23 posterior mac, 1 ms and 2 sens; ms inner to sens; m 1i present on one side in a specimen; mac m 4i rarely absent. Th. III with 3 0‒31 mac and 2 lateral sens; m 5i and a 6i as mac (Fig. 20). Abd. I with 8(7) (a2, a3, m2–4, m 2i, m 4i, m4p) mac, 1 ms and 1 sens; sens inner to ms; a2 as mac in one specimen and mic in another specimen; mac m 4i rarely absent. Abd. II with 3 (m3, m3e, m3ep) central, 1 (m5) lateral mac and 2 sens. Abd. III with 1 (m3) central, 3 (am6, pm6, p6) lateral mac and 2 sens; ms absent (Fig. 21). Abd. IV with 6 central (I, M, B4, B5, A5, A6) and 6 lateral mac (D3, E2–4, E2p, F1) (Fig. 22); two sens (as, ps) of normal length and others elongate (not represented). Abd. V with 3 sens (Fig. 23).

Ecology. In aphotic zone of cave.

Etymology. Named after Miss Liu, who helped to collect the animals.

Remarks. Sinella liuae sp. nov. is characterized by presence of small chaetae X and X2‒4 posterior to labium, 6+6 central mac on Abd. IV, and truncate unguiculus. It is closest to S. sineocula in claw structure, “smooth” inner differentiated tibiotarsal chaetae, long mucronal spine, ciliate post-labial chaetae X, X2 and X4, and chaetotaxy of Abd. I‒Abd. III, but differs from the latter in pointed tenent hairs and 6+6 central mac on Abd. IV (Table 1).