Spinonychiurus sinensis, Sun, Xin & Li, Yu, 2014

Sun, Xin & Li, Yu, 2014, New Chinese record of the genus Spinonychiurus (Collembola, Onychiuridae), with the description of a new species, ZooKeys 439, pp. 19-26 : 21-23

Taxon classification Animalia Poduromorpha Onychiuridae

Spinonychiurus sinensis sp. n. Figs 1-2

Type material.

Holotype: female; paratypes: 3 females and 1 male on slides - China, Jilin, Changbai Mountain Range (alt. 689 m, 43.0376°N, 128.9965°E), 3.Oct.2011, litter and soil, Berlese extraction, leg. Tang Xuguang.

Diagnosis.

Pso formula as 32/133/33343 dorsally, absent ventrally, subcoxa 1 of legs I-III with 1, 1 and 1 pso respectively; psx formula as 11/000/122211m ventrally, absent dorsally, subcoxa 1 of legs I-III with 1, 1 and 1 psx respectively; S-chaetae formula as 1/011/111021 dorsally, 11/000/000110 ventrally; sterna of Th. I, II, and III with 0+0, 2+2, 2+2 chaetae respectively; Abd. IV tergum with axial chaeta p0, Abd. V tergum with a0 and m0, Abd. VI tergum with a0; the distal row of tibiotarsi with 7 chaetae; male ventral organ absent; anal spines present, 0.8 times as long as inner edge of hind unguis.

Description.

Body white in alcohol. Size 970-1200 µm in females, 900 µm in male; holotype: 1200 µm. Body subcylindrical, body sides parallel.

Pseudocellar formula: 32/133/33343 dorsally, absent ventrally (Figs 1A, G, 2A), subcoxa 1 of legs I–III with 1, 1 and 1 pso respectively. Parapseudocellar formula: 11/000/122211m ventrally, absent dorsally (Figs 1A, 1G, 2A), subcoxa 1 of legs I–III with 1, 1 and 1 psx respectively. Pseudopore formula: 0/011/11110 dorsally, -/111/- ventrally (Figs 1A, G, 2A).

Head. Antennae short and distinctly segmented, as long as head. Length ratio of Ant. I: II: III: IV as about 1: 2: 2: 2. Ant. IV with two distinct thickened S-chaetae, subapical organite with globular apex; basolateral ms at approx. half length from base, above the second proximal row of chaetae (Fig. 1E). AIIIO composed of 5 papillae, 5 guard chaetae, 2 sensory rods and 2 smooth sensory clubs, the inner bigger than the outer, and a lateral ms (Fig. 1E). Ant. II with 15 chaetae. Ant. I with 9 chaetae. Antennal base not marked (Fig. 1D). PAO with 12-13 compound vesicles (Fig. 1D). Dorsal cephalic chaeta d0 absent (Fig. 1A). 3+3 p-chaetae present between two inner posterior pso, p1 in line with others (Fig. 1E). Mandible with strong molar fig and 4 apical teeth. Maxilla bearing 3 teeth and 6 lamellae. Maxillary palp simple with 1 basal chaeta, without sublobal hair (Fig. 1B). Labral formula 4/1,4,2; labium with 6 proxi mal, 4 basomedian (E, F, G, f) and 6 basolateral (a, b, c, d, e, e’) chaetae (Fig. 2A); labial type A, papillae A–E respectively with 1, 4, 0, 3 and 3 guard chaetae (Fig. 1C). Head ventrally with 4+4 postlabial chaetae along ventral groove (Fig. 2A).

Body chaetotaxy. S-chaetae subcylindrical, apically rounded, 1/011/111021 dorsally, 11/000/000110 ventrally (Fig. 1A, G); subcoxae 2 of legs I, II and III with 0, 0, 1 S-chaeta respectively. Tiny and blunt ms, present on Th. II–III (Fig. 1A). Ordinary chaetae differentiated into meso- and macrochaetae, ratio Sp: m1: p1 on Abd. V tergum = 1: 1: 2.5. Th. I tergum with 7+7 dorsal chaetae. Th. II–Abd. III terga with 3+3 chaetae along axis respectively (Fig. 1A). Abd. IV tergum with one axial chaeta (p0), Abd. V tergum with two axial chaetae (a0 and m0), Abd. VI tergum with one axial chaeta (a0) (Figs 1A, 2D). Sterna of Th. I, II, and III with 0+0, 2+2, 2+2 chaetae respectively.

Appendages. Subcoxa 1 of legs I–III with 4, 5 and 5 chaetae, subcoxa 2 with 1, 4 and 4 chaetae respectively. Tibiotarsi of legs I, II and III with 16 (1, 8, 7), 16 (1, 8, 7) and 15 (1, 7, 7) chaetae each (Fig. 1F). Unguis without teeth. Unguiculus approx. 0.6 times as long as inner edge of unguis, with inner basal lamella (Fig. 1F). Ventral tube with 4+4 basal and 7+7 distal chaetae. Furca reduced to a field of fine granulation with 4 small dental chaetae arranged in 2 rows posteriorly; only one manubrial row of chaetae posterior to dental chaetae (Figs 1G, 2B, C).

Genital fig with 9-11 chaetae in females, 32 chaetae in male. Male ventral organ absent. Anal valves with numerous acuminate chaetae; each lateral valve with a0, 2a1, 2a2; upper valves with chaetae a0, 2b1, 2b2, c0, 2c1, 2c2. Anal spines set on distinct papillae, 0.8 times as long as inner edge of hind unguis.

Derivatio nominis.

Named for the first recordof the genus Spinonychiurus in China.

Ecology.

Found in the coniferous forest.

Discussion.

The new species is closest to the genus Spinonychiurus in two important characters: two subsegments on Abd. III sternum and the absence of d0 on the head. However, it does not fit the current definition of the genus as proposed by Kaprus’ and Tsalan (2009) in having 7 chaetae in the distal row of tibiotarsi instead of 11. The distal tibiotarsal chaetae have been verified to be an unstable character in the generic level ( Sun et al. 2010; Sun et al. 2011; Sun and Zhang 2012; Sun et al. 2013), so we propose the placement of the new species in the genus Spinonychiurus and broaden its diagnosis accordingly. The main diagnostic characters of all known species of the genus are given in Table 1 and a key to these species is provided below.