Thalassaphorura problematica Sun, X, Deharveng, L, Wu & D-H 2013

Body white in alcohol. Size 1000-1300 µm in females, 800–1100 µm in male; holotype: 1050 µm. Body subcylindrical, body sides parallel. Pseudocellar formula: 32/133/33343 dorsally, 11/000/00010 ventrally, subcoxa 1 of legs I-III with 2, 2 and 2 pso respectively (Fig. 1A, B). Parapseudocellar formula: 0/000/112001+1m (each of anal valve with one psx) ventrally, absent dorsally (Figs 1A, B, 2G). Pseudopore formula: 0/011/11110 dorsally, 00/111/0001m0 ventrally (Fig. 1A, B). Head. Antennae short and distinctly segmented, as long as head. Length ratio of Ant. I: II: III: IV as about 1: 1.5: 1.5: 1.5. Subapical organite of Ant.IV with globular apex; basolateral ms at about 1/3 length from base, above the second proximal row of chaetae (Fig. 1F). Ant. III sensory organ composed of 5 papillae, 5 guard chaetae, 2 sensory rods and 2 granulated clubs, the inner bigger than the outer, and a lateral ms (Figs 1D, F). Ant. II with 13 chaetae. Ant. I with 8 chaetae. Antennal base well marked. PAO composed of 20–24 simple vesicles (Fig. 1C). Dorsal cephalic chaeta d0 absent (Figs 1A, 2A). 3+3 p-chaetae present between two inner posterior pso, p1 anterior to others. Mandible with strong molar plate and 4 apical teeth. Maxilla bearing 3 teeth and 6 lamellae. Maxillary palp simple with 1 basal chaeta and 2 sublobal hairs. Labral formula 4/1,4,2;. Labium with 5 proximal, 4 basomedian (E, F, G, f) and 5 basolateral (b, c, d, e, e’) chaetae (Fig. 2B); labial type AB, papillae A–E respectively with 1, 4, 0, 3 and 2 guard chaetae (Fig. 1E). Head ventrally with 4+4 postlabial chaetae along ventral groove (Fig. 2B). Body chaetotaxy. S-chaetae subcylindrical, apically rounded, 11/011/222121 dorsally, 11/000/000110 ventrally (Figs 1A, B); subcoxae 2 of legs I, II and III with 0, 0, 1 S-chaeta respectively. Tiny and blunt ms, present on Th. II–III. Ordinary chaetae differentiated into meso- and macrochaetae, ratio Sp: m1: p1 on Abd. V tergum = 1: 2–2.3: 0.8. Th. I tergum with 7–8+7–8 dorsal chaetae. Th. II–III terga with 4+4 chaetae and Abd. I–III terga with 3+3 chaetae along axis respectively (Fig. 1A). Abd. IV–V terga with one axial chaeta (p0) each, sometimes with asymmetric chaetae along axis. Abd. VI tergum with two axial chaetae (a0 and p0) (Figs 1A, 2C). Sterna of Th. I, II, and III with 0+0, 1+1, 1+1 chaetae respectively. Appendages. Subcoxa 1 of legs I–III with 4, 5 and 5 chaetae, subcoxa 2 with 0, 4 and 4 chaetae respectively. Tibiotarsi of legs I, II and III with 14 (1, 7, 6) chaetae each (Fig. 2E). Unguis without teeth. Unguiculus short, about 0.3 times as long as inner edge of unguis, with inner basal lamella (Fig. 2E). Ventral tube with 1+1 basal and 8–11+8–11 distal chaetae (8–10+8–10 in female, 11+11 of which 9+9 modified in males) (Fig. 2D). Furca reduced to a field of fine granulation with 4 small dental chaetae arranged in 2 rows posteriorly; only one manubrial row of chaetae present posteriorly to dental chaetae (Fig. 2F). Genital plate with 14–15 chaetae in females, 33–36 chaetae in male. Anal valves with numerous acuminate chaetae; each lateral valve with a0 and 2a1; upper valves with chaetae a0, 2b1, 2b2, c0, 2c1, 2c2 (Fig. 2G). Anal spines set on distinct papillae, 1.1–1.2 times as long as inner edge of hind unguis.