Thalassaphorura linzhiensis, Sun, Xin & Li, Yu, 2015

Sun, Xin & Li, Yu, 2015, New Chinese species of the genus Thalassaphorura Bagnall, 1949 (Collembola: Onychiuridae), Zootaxa 3931 (2), pp. 261-271 : 268-270

Thalassaphorura linzhiensis sp. nov.

Figs 25–35

Type material. Holotype male, China, Tibet, Linzhi, Sejila Mountains (alt. 4339 m, 29˚36’50” N, 94˚41’20” E), 18 August 2012, litter and soil in the broadleaved forest, Berlese extraction, Zhang Feng leg. Paratypes 10 females and 6 males, same data as holotype.

Description. Body white in alcohol. Length of body 0.90–1.00 mm in females, 0.80–0.83 mm in males; holotype 0.83 mm. Shape of body: cylindrical with anal spines on papillae. Anal spines 0.6 times as long as inner edge of hind unguis.

Pso formulae 32/233/33343 dorsally and 11/000/01120 ventrally ( Figs 25, 26, 31 ). Subcoxae 1 of legs I–III with 2 pso each. Psx formulae 00/000/100000 ventrally and absent dorsally ( Figs 25, 26, 31 ). Subcoxae 1 of legs I–III without psx. Psp formulae 00/011/ 111100 dorsally and 00/111/0001m0 0 ventrally ( Figs 25, 26, 31 ).

Head. Antennae as long as head. Length ratio of Ant. I: II: III: IV as about 1: 1.5: 1.5: 2.3. Subapical organite on Ant. IV with globular apex; basolateral ms at about 1/5 length from the base, above the first proximal row of chaetae. Ant. III sensory organ consists of 5 papillae, 5 guard chaetae, 2 small rods, and 2 smooth sensory clubs; lateral ms just behind sensory organ ( Fig. 27 ). Ant. II with 13 chaetae. Ant. I with 8 chaetae. Antennal base not clearly marked. PAO with 21–23 simple vesicles arranged in two rows along axis of organ ( Fig. 32 ). Dorsal cephalic chaeta d0 present. On head 3+3 p-chaetae present between two posterior pso, p1 anterior to others ( Fig. 32 ). Mandible with strong molar plate and 4 apical teeth. Maxilla bearing 3 teeth and 6 lamellae. Maxillary palp simple with 1 basal chaeta, with 2 sublobal hairs. Labral chaetae 4/142. Labium with 6 proximal, 4 basomedian (E, F, G, and f) and 6 basolateral (a, b, c, d, e, e’) chaetae; labial type AC, papillae A–E with 1, 4, 0, 3 and 2 guard chaetae respectively ( Fig. 28 ). Postlabial chaetae 4+4 along ventral groove ( Fig. 26 ).

Body chaetotaxy. S-chaetae not well differentiated from ordinary chaetae. Tiny and blunt ms present on both Th. II and III ( Fig. 25 ). Th. I tergum with 5+5 chaetae. Th. II–III terga and Abd. II–III terga with 3+3 chaetae along axial line in both sexes, while tergum of Abd. I in females with 3+3 chaetae and only 2+2 chaetae in males, unpaired axial chaetae absent ( Figs 25, 30 ). Abd. IV tergum with one axial chaeta m0, Abd. V tergum often with asymmetrical chaetae, Abd. VI tergum with two axial chaetae a0 & m0 ( Fig. 34 ). Th. I–III sterna with 1+1, 1+1, 1+1 chaetae respectively.

Appendages. Subcoxae 1 of legs I–III with 4, 4 and 4 chaetae, subcoxae 2 with 1, 4 and 4 chaetae respectively. All tibiotarsi of with 18 (1, 8, 9) chaetae ( Fig. 29 ). Unguis without teeth. Unguiculus 0.6 times as long as inner edge of unguis, without inner basal lamella ( Fig. 29 ). Ventral tube with 1+1 anterior chaetae, 6+6 distal chaetae and 2+2 basal chaetae. Furca reduced to finely granulated area, with 4 small dental chaetae arranged in two rows posteriorly and one manubrial row of chaetae ( Figs 31 , 33 ).

Genital plate with 14–21 chaetae in females, 34–36 in males. Male ventral organ absent. Anal valves with numerous acuminate chaetae; each lateral valve with chaetae a0, 2a1 and 2a2; upper valve with chaetae a0, 2b1, 2b2, c0, 2c1 and 2c2 ( Fig. 35 ).

Ecology. In the litter and soil of broadleaved forest.

Derivatio nominis. Named after the type locality.

Discussion. T. linzhiensis sp. nov. is most similar to T. hainanica Sun, Gao & Potapov, 2014 from South China as having the same pso formulae on the body (32/233/33343 dorsally, 11/000/01120 ventrally), 2 pso on each subcoxa 1 of legs, 5 papillae and 5 guard chaetae in AIIIO, 3+3 medial p-chaetae present between posterior pso on head, labial papillae of AC type, 5+5 chaetae on Th. I tergum, chaetae on ventral tube as 1+1/6+6/2+2 and 9 distal chaetae on tibiotarsi. These two species can be easily distinguished by shape of S-chaetae (like ordinary chaetae in the new species versus well maked in T. hainanica ), the number of vesicles in PAO (more than 20 in the new species versus less than 16–17 in T. hainanica ), the number of axial chaetae on Abd. VI (a0 and m0 in the new species versus only a0 in T. hainanica ), the presence/absence of chaetae on Th. I sternum (1+ 1 in the new species versus none in T. hainanica ) and the length of AS (0.6 times as long as inner edge of hind unguis on distinct papillae in the new species versus 0.3 times on indistinct papillae in T. hainanica ).

Figures

FIGURE 25 – 31. Thalassaphorura linzhiensis sp. nov. 25, dorsal side of body; 26, ventral side of head; 27, AIIIO; 28, labium; 29, distal part of leg III; 30, chaetotaxy of Abd. I tergum in female; 31, ventral side of Abd. II – IV. Scales: 0.1 mm (25 – 26, 30 – 31), 0.01 mm (27 – 29).

FIGURE 32 – 35. Thalassaphorura linzhiensis sp. nov. 32, dorsal side of head; 33, ventral side of Abd. IV – V in female; 34, Abd. IV – VI terga; 35, anal valves. Scales: 0.1 mm.