Scolopendrella immaculata Newport, 1845. Valid name: Scutigerella immaculata (Newport, 1845).

Trunk with 15 tergites. Four macrosetae (a1–a4) around the antennal base, rarely seta a3 absent. Posterior margins of tergites emarginated. Last tergite with a deep cavity between cerci. First pair of legs with 4 segments, others with 5 segments. Styli present at the base of legs 3–12. Coxal sacs present at the base of legs 3–10.

Sub-cosmopolitan (Szucsich and Scheller 2011).

Scutigerella sinensis sp. nov. is characterized by absence of a3 seta around the antennal base, 6–8 setae on the first tergite, deeply emarginated posterior margin of tergite 2, 28–37 marginal and 41–57 inner setae on tergite 2, less differentiated marginal setae on all tergites, femur of first pair of legs without a conspicuous ventral process, posterior styli without a lateral seta, cavity of fifteenth tergite V-shaped, tarsus of last pair of legs moderately set with setae, cerci 2.7–3.4 times as long as width, cerci densely covered with subequal setae, cerci without expansion in terminal area.

Holotype : male (slide no. SH-DJS-SY2015009) (SNHM), China, Shanghai, Dajinshan Island, extracted from soil samples of bamboo forest, alt. 103 m, 30°41'N, 121°26'E, 30-VI-2015, coll. Y. Bu & Y. L. Jin. Paratypes: 1 female (slide no. SH-DJS-SY2017001), ibidem, 11-XI-2017; 1 female (slide no. SH-DJS-SY2017002), ibidem, extracted from soil samples of broad-leaf forest, 11-XI-2017, coll. Y. Bu & Y. L. Jin; 1 female (slide no. SH-DJS-SY2018003), ibidem, 24-IV-2018, coll. Y. Bu & J. Y. Li; 1 male (slide no. SH-DJS-SY2018001), ibidem, extracted from soil samples of broad-leaf forest, 24-X-2018, coll. Y. Bu & J. Y. Li; 1 female (slide no. BJ-YMY-SY2021001), China, Beijing, Yuan-Ming Yuan Imperial Garden, extracted from soil samples of a deserted field with herbaceous plants, alt. 60 m, 40°1'N, 116°17'E, 15-IV-2021, coll. R. Q. Wang. Non-type specimens: 1 juvenile with 8 pairs of legs (slide no. SH-DJS-SY2015002), same data as holotype; 1 juvenile with 9 pairs of legs (slide no. SH-DJS-SY2015111), ibidem, 22-IX-2015, coll. Y. Bu & Y. L. Jin; 1 juvenile with 11 pairs of legs (slide no. SH-DJS-SY2018002), ibidem, 24-IV-2018, coll. Y. Bu.

Adult body 3.4 mm long on average (3.0–4.3 mm, N = 6), holotype 3.2 mm (Fig. 1A).

Figure 1. 

Scutigerella sinensis Jin & Bu, sp. nov. A habitus, dorsal view in alcohol B head, dorsal view (a1, a2 and a4–macrosetae around antennal base) C tergites 1–2 D tergite 3 E first maxilla and the right part of second maxilla (arrows indicate spined organs) F head, ventral view G male genitalia H right 10–11 antennomeres, dorsal view (arrows indicate spiniform sensory organs) I right 13–14 antennomeres, ventral view (arrows indicate sensory setae) J stylus and coxal sac on base of leg 5 (arrow indicates stylus). Scale bars: 500 μm (A); 20 μm (B–J).

Head length 300–350 μm, width 320–420 μm, broadest part just posterior of midlength, dorsally covered with straight setae of varying lengths (Fig. 1B). Antennal base with 3 macrosetae: a1, a2 and a4 (33–50 μm), a3 absent (Fig. 1B). Longest seta (43–53 μm) located between Tömösváry organ and spiracle, same length with greatest width of third antennomere. Reticulation of cuticular thickenings present on frons. Central rod complete (150–187 μm), less distinct at most anterior portion, 0.5 times the length of head, with distinct ovoid swollen end (Fig. 1B). Dorsal cuticle of head glabrous.

Tömösváry organ subspherical, length 20–22 μm, width 15–20 μm, 0.3–0.4 times as wide as greatest diameter of third antennomere (Fig. 1B).

Mouthparts. Mandible similar to Hanseniella. Pars incisivus with four distinct thick teeth, pars molaris with four smaller teeth and one proximal spine, lacinia mobilis with 2 pubescent processes observed from lateral view under light microscope (Fig. 2A). First maxilla has two lobes, inner lobe with 4 hook-shaped dorsal teeth and 1 tiny ventral tooth, palp small, with three pointed branches, middle one distinctly longer than lateral ones (Fig. 2B). Second maxilla with many small protuberances anteriorly, each carrying one seta, distal setae thicker and spiniform, posterior part with sparse setae, 3+3 spined organs present on anterolateral margin (Fig. 1E, F). Cuticle of second maxilla covered with dense pubescence.

Figure 2. 

Scutigerella sinensis Jin & Bu, sp. nov. A mandible, lateral view (pi–pars incisivus, pm–pars molaris, lm–lacinia mobilis) B first maxilla C right 6–7 antennomeres, dorsal view (co–conical sensory organ, spo–spiniform sensory organs, so–spined sensory organs) D right 13–14 antennomeres, ventral view (S–sensory setae) E terminal two antennomeres, dorsal view F femur and tibia of leg 1, ventral view. Scale bars: 20 μm.

Antennae with 19–29 antennomeres (holotype with 29), about 0.4 of body length. First antennomere cylindrical, 1.3–2.5 times wider than long (length 30–45 μm, width 50–75μm), with 5–6 setae in one whorl, longest seta 28–30 μm, about half of antennomere width. Second antennomere 1.3–1.9 times wider than long (width 48–65 μm, length 33–40 μm), with 7–9 setae evenly inserted, longest seta inserted outer-dorsally, about 0.5–0.7 times as long as antennomere width. Third antennomere 1.3–1.9 times wider than long (length 25–40 μm, width 45–65μm), with primary whorl of 7–10 setae, longest seta 0.5–0.7 times as long as antennomere width. Setae on proximal antennomeres longer and on distal antennomeres shorter. Proximal antennomeres each with only primary whorl of setae. Secondary whorl setae appear from antennomeres 6–8 to penultimate antennomere (Figs 1H, I, 2C, D). Four kinds of sensory organs observed on antenna: spiniform sensory organs present on antennomeres 3–5 to distal antennomere increasing in number from 2 to 8, short and thick on proximal antennomeres (Fig. 2C, D), long and slender on distal ones (Figs 1H, 2E); one small spined sensory organ consists of several spine and central stub present on dorsal side from fourth antennomere onwards to subdistal antennomere, rarely absent (Fig. 2C, E); single tiny conical sensory organ present on outer side of several antennomeres discontinuously distributed along the antenna (Fig. 2C); one huge spined sensory organ only present on distal antennomere, distinctly bigger than small ones (Fig. 2E). Additionally, one sensory seta decorated with transverse stripes always present on ventral side from second antennomere onwards to penultimate antennomere (Figs 1I, 2D). Distal antennomere longer than wide (length 58–70 μm, width 50–58 μm), with 1 huge spined sensory organ consisting of three or four curved spines stemming from one central stalk on elevated base about 0.3–0.4 times as long as width of antennomere and two neighboring medium ones, 4–7 spiniform organs and 15–22 normal setae on distal half (Fig. 2E). Cuticular reticulation present on first and second antennomere, mainly transverse. All antennomeres pubescent. Chaetotaxy and sensory organs of antennae of holotype are given in Table 2.

Tergites. Tergite 1 rudimentary, with 6–8 subequal setae in one row (Fig. 1C). Tergite 2 complete, 1.6 times wider than long (width 295–245 μm, length 155–185 μm), posterior margin deeply emarginated, with 28–37 subequal marginal setae, longest one (25–27 μm) 1.7–1.8 times as long as shortest one (15–17 μm), 0.4–0.6 and 0.2 times as third antennomere respectively; areas surrounded by marginal setae covered by 41–57 inner setae, similar to marginal setae; anterior half with short pubescence on mesh-work covered cuticular thickenings, posterior half with fine dense pubescence (Fig. 1C). Tergite 3 complete, broader and longer than tergite 2, 1.5–1.6 times wider than long (width 305–382 μm, length 190–240 μm), posterior margin deeply emarginated, with 36–42 subequal marginal setae, longest one (22–29 μm) 1.7–1.8 times as long as shortest one (12–17 μm), with 58–89 subequal inner setae (Fig. 1D). Tergite 4 broader than tergite 3, with 32–39 subequal marginal setae and 44–66 subequal middle setae. Shape of tergites 5–7, 8–10, and 11–13 similar as tergites 2–4. Pattern of alternating tergite lengths of two short-tergites followed by one long-tergite but disrupted at tergite 13. Last tergite with a V-shaped cavity located medially on posterior border. Anterolateral setae on all tergites not differentiated. Cuticle of all tergites densely pubescent. Posterior border of tergites glabrous (Fig. 1C, D).

Legs. First pair of legs with 4 segments, trochanter absent; femur 1.8–2.0 times longer than wide (length 38–85 μm, width 28–43 μm), with cuticular reticulation (Fig. 2F), with 9–11 setae (Fig. 3A), longest seta (33–43 μm) 0.8–1.1 times as long as greatest width of femur; tibia 1.1–1.4 times as long as wide (40–50 μm, 30–38 μm), with total 4 or 5 setae, long pectinate setation (tibial pecten) present distolaterally (Fig. 2F), dorsal longest seta (23–28 μm) about 0.6–0.9 times as long as greatest diameter of tibia; tarsus about 3.3–4.6 times as long as wide (65–115 μm, 20–25 μm), slowly tapering towards distal end, with 8–14 setae, longest dorsal setae (18–25 μm) 0.8–1.0 times as long as greatest width of tarsus (Fig. 3A). Two slightly curved claws, anterior one somewhat broader and longer than posterior one (Fig. 3A). Leg 12 with 5 segments, 1.0–1.6 times as long as length of head; trochanter 1.4–1.7 times as long as wide (113–150 μm, 75–95 μm), dorsal side with cuticular reticulation, with 11–25 setae in total, longest one (20–21 μm) 0.2–0.3 times of greatest width of podomere (Fig. 3B); femur 1.1–1.3 times as long as wide (55–95 μm, 58–75 μm), with 6–14 setae and dorsal longest seta (23–28 μm) about 0.3–0.5 times as long as width of podomere (Fig. 3B); tibia nearly 1.5–1.9 times longer than wide (80–125 μm, 55–68 μm), with 5 or 6 longitudinal rows of setae, each row with 2–5 setae, longest outer seta (23–30 μm) 0.2–0.3 times as long as greatest width of podomere (Fig. 3B); tarsus 2.9–4.0 times as long as wide (105–150 μm, 38–43 μm) with 5 or 6 longitudinal rows of setae, each row with 2–6 setae, outer rows of setae straight and protruding, other setae slightly curved and short, longest seta (23–25 μm) 0.6–0.7 times as long as greatest width of podomere, 4–6 spiniform setae in a row present on ventral surface (Fig. 3B). Two claws slightly curved, almost same size. All legs covered with dense pubescence except areas with cuticular reticulation.

Figure 3. 

Scutigerella sinensis Jin & Bu, sp. nov. A leg 1, dorsal view B leg 12, ventro-lateral view (arrows indicate spiniform setae) C left cercus, dorsal view. Scale bars: 20 μm.

Coxal sacs present at bases of legs 3–10, fully developed, each with 5 or 6 setae on surface (Fig. 1J). Corresponding area of leg 1, 2, 11, and 12 replaced by 2–3, 2–6, 2–3 and 1 seta respectively.

Styli present at base of legs 3–12, 2.6–4.3 times as long as wide (33–58 μm, 10–20 μm), pubescent, with two distal setae, subapical seta (15–23 μm) 0.3–0.5 times as long as stylus, apical seta (8–10 μm) 0.2–0.3 times as long as stylus, both with pointed apex (Fig. 1J).

Sense calicles located on two ventral protuberances of last tergite, posterior to base of leg 12, with smooth margin around pit. Sensory seta inserted in cup center, extremely long (235–275 μm).

Cerci about 0.7–0.9 of head length, distinctly shorter than leg 12, 2.7–3.4 times as long as its greatest width (240–300 μm, 80–110 μm), moderately covered with subequal setae (Fig. 3C). Dorsally with 30–59 setae, ventrally with 26–57 setae; longest seta (28–33 μm) 1.3–1.5 times as long as shortest seta (20–28 μm), 0.3–0.4 times as long as greatest width of cercus and 0.1 times as length of cercus. Terminal area glabrous, 0.1 times as long as cercus. Two apical setae pointed, longer seta (43–58 μm) 0.2 times as long as cercus, with granules; shorter seta about a third of the length of longer one. Cuticle with dense pubescence.

Male genitalia with 30 setae in total in holotype, without specialized setae (Fig. 1G).

This new species is named after the country of origin, from the Latin adjective sinensis, meaning Chinese.

China (Shanghai, Beijing).

Our current investigation indicates that Scutigerella sinensis sp. nov. is a rare species in natural habitats with very low density. We found about ten individuals among several hundred symphylans from plots of different vegetation. This Scutigerella is often coexisting with other dominant species of Hanseniella and Symphylella in the upper soil layer (0–10 cm) or humus.

The head chaetotaxy was briefly described in the previous studies of Scutigerella, usually with only shapes and numbers mentioned. The macrosetae around the base of the antenna of Scutigerella have been noticed and named by former researchers, and all species examined until now have a complete set of four macrosetae (a1–a4), which was deemed as a good diagnostic character in the taxonomy of Scutigerella (Hinschberger 1950; Juberthie-Jupeau and Tabacaru 1968; Scheller 1986). Scutigerella sinensis sp. nov. has three macrosetae (a1, a2, and a4) around the antennal base, with a3 seta absent, which can be easily distinguished from all other congeners. Our observation indicates this character is stable in both adults and juveniles and can be a unique feature of the new species. The present new species is most similar to the cosmopolitan species Scutigerella immaculata (Newport, 1845) in the shapes and chaetotaxy of tergites and legs, but differs in the absence of the a3 seta on the head (present in S. immaculata), number of marginal setae on tergite 2 and 3 (less than 50 in S. sinensis sp. nov. vs. more than 50 in S. immaculata), and the shape of the stylus (tapering in S. sinensis sp. nov. vs. cylindrical in S. immaculata).