Symphylella isabellae (Grassi, 1886), described from Italy.

Symphylella macrochaeta sp. nov. is characterized by 10 extremely long macrosetae arranged as 4/4/2 on the frons, 4+4 setae on the first tergite and broad triangular processes on tergites.

Holotype : female (slide no. ZJ-ZS-SY2020029) (SNHM), China, Zhejiang Province, Zhoushan City, Changgang Mountain Forest Park, extracted from soil samples of broad-leaf forest, alt. 250 m, 30°2'N, 121°7'E, 17-XI-2020, coll. Y. L. Jin et al.

Paratypes : 10 females (slides no. ZJ-ZS-SY2020006, ZJ-ZS-SY2020008, ZJ-ZS-SY2020014–ZJ-ZS-SY2020016, ZJ-ZS-SY2020024–ZJ-ZS-SY2020028) (SNHM), same data as holotype. 2 females (slides no. SH-JZGY-SY2017032, SH-JZGY-SY2017034), China, Shanghai, Jiuzi Park, extracted from soil and litter samples of bamboo forest, alt. 14 m, 31°15'N, 121°28'E, 25-V-2017, coll. Y. L. Jin.

Non-type specimens : 18 juveniles with 7–10 pairs of legs, same data as holotype; 5 juveniles with 9 or 10 pairs of legs, China, Shanghai, Jiuzi Park, extracted from soil and litter samples of bamboo forest, alt. 14 m, 31°15'N, 121°28'E, 25-V-2017, coll. Y. L. Jin; 1 juvenile with 10 pairs of legs, China, Shanghai, Tianma Mountain, extracted from soil samples of bamboo forest, alt. 98 m, 31°5'N, 121°9'E, 10-V-2017, coll. Y. Bu.

Adult body 2.1 mm long in average (1.9–2.2 mm, n = 11), holotype 2.1 mm (Fig. 1A).

Head length 250–280 μm, width 223–265 μm, with widest part on equal level of points of articulation of mandibles. Central rod distinct in both anterior (65–70 μm) and posterior (75–85 μm) parts, with an obvious middle node-like interruption. Head dorsally covered with setae of different lengths (Fig. 1B). Frons with 5+5 lateral setae, 10 extremely long macrosetae (58–73 μm) arranged as 4/4/2 (counted from anterior row to posterior row) and 4–5.6 times as long as antero-central seta (a0) (Fig. 3H), and 20–21 short to medium-length setae (8–16 μm) (Figs 1B, 3H). Cuticle on anterolateral part of head with coarse granules (Fig. 1B).

Tömösváry organ globular, diameter 15–20 μm, about half of greatest diameter of third antennomere (35–40 μm), opening round (9–12 μm), inner margins of opening covered with regular vertical striae (Fig. 1E).

Mouthparts. Mandible composed by pars incisivus (pi) and pars molaris (pm), with movable appendage lacinia mobilis (lm) inserted between them. Pars incisivus with 4 distinct thick teeth, pars molaris with 4 smaller teeth and 2 proximal spines, and lacinia mobilis with only 1 blunt process observed from lateral view (Fig. 3A). First maxilla has 2 lobes, inner lobe with 6 hook-shaped teeth and pubescent apically, palp pointed (Fig. 3B). Anterior part of second maxilla with many small protuberances, each carrying 1 seta, distal setae thicker and spiniform; posterior part with sparse setae. Cuticle of second maxilla covered with dense pubescence.

Antennae with 16–20 antennomeres (18 in holotype), about 0.2 of body length. First antennomere cylindrical, length about 0.5–0.8 of greatest diameter (width 33–40 μm, length 18–25 μm), with 6 or 7 setae in 1 whorl, longest inner seta 16–18 μm (Fig. 3C). Second antennomere wider (35–38 μm) than long (27–33 μm), with 8 setae evenly inserted around antennal wall with interior setae (15 μm) slightly longer than exterior ones (11 μm) (Fig. 3C). Chaetotaxy of third antennomere similar to preceding ones. Setae on proximal antennomeres longer and on distal antennomeres shorter. Proximal antennomeres with only primary whorl of setae (Fig. 3C). Secondary whorl appearing ventrally on antennomeres 6–8. Four kinds of sensory organs observed on antenna: rudimentary spined sensory organs (rso) on dorsal side of most antennomeres (Fig. 3C, D); spined sensory organs (so) with more surrounding spines and larger than rso, only present on apical antennomere (Fig. 3D, E); cavity-shaped organs (co) on antennomeres 6 and 7 next to subapical one (Fig. 3D); bladder-shaped organs (bo) on antennomeres 9–11 next to subapical one increasing in number on subdistal antennomeres to 15 in maximum (Fig. 3D, E). Apical antennomere subspherical, with its length as long as width (28–30 μm), with 5 spined sensory organs consisting of 3 or 4 curved spines around a central pillar and 12–16 setae located distally (Fig. 3D, E). All antennomeres covered with short pubescence. Chaetotaxy and sensory organs on antennae of holotype are given in Table 1.

Trunk with 17 tergites. Tergites 2–13, and 15 each with 1 pair of triangular processes. Length from base to tip of processes somewhat shorter than or same as its basal width; basal distance between processes longer than their length from base to tip except on tergites 2 and 3 (Table 3). All processes with roundish swollen ends (Figs 1C, 2A–D). Definition of chaetotaxy on tergite as follow: anterolateral setae (als) located on anterolateral angle of each tergite; apical seta (as) most close to process apex; lateromarginl setae (lms) located on lateral margin of process and including als and as; inner basal setae (ibs) located on inner base of process; inserted setae (is) present between ibs and as; central setae (cs) present between base of processes; other setae including all setae except above nominated ones (Fig. 2A). Anterolateral setae of tergites 2, 3, 5, 6, 8, 9 11 and 12 slightly shorter than length of process of same tergite, that of tergites 4, 7, 10, 13 and 15 subequal or slightly longer than length of process of same tergite. Processes with 1 or 2 inserted setae. All tergites pubescent (Fig. 2A–D).

Tergites. Tergite 1 reduced, with 4+4 setae of different length (Fig. 1G). Tergite 2 complete, with 2 broad triangular posterior processes, 6 or 7 lateromarginal setae, 1 or 2 inserted setae, 1 or 2 central setae (Table 2), with anterolateral setae 0.8–0.9 time as long as length of process, length of processes 0.8–1.0 time as long as broad, basal distance between processes 0.6–0.9 time as long as their length (Figs 1C, 2A). Tergite 3 complete, broader and longer than preceding one, with ratios of 0.7–0.9, 0.8–1.0, and 0.6–0.9 respectively, 8–10 lateromarginal setae, 1 or 2 inserted setae, 1–3 central setae (Figs 1C, 2B). Tergite 4 broader than tergite 3, with ratios 1–1.3, 0.6–0.7, and 1.3–2.5 respectively, 5–7 lateromarginal setae (Fig. 2C). Chaetotaxy of tergites 5–7, 8–10, and 11–13 similar as tergites 2–4 (Fig. 2D). Pattern of alternating tergite lengths of 2 short-tergites followed by long-tergite only disrupted at caudal end (Table 3). Tergites 14 and 16 without processes and with 17–26 and 12–17 setae respectively (Fig. 1D). Tergite 17 with 27–38 setae. Chaetotaxy and measurements of tergites are given in Tables 2 and 3.

Legs. First pair of legs reduced to 2 small hairy cupules, each with 1 long seta (9–10 μm) (Fig. 1F). Basal areas of legs 2–12 each with 3–8 setae (Fig. 1H). Leg 12 0.8–0.9 time as long as length of head (Fig. 3I), trochanter 1.1–1.2 times as long as wide (50–75 μm, 41–67 μm), with 7 setae; femur almost as long as wide (35–40 μm, 30–40 μm), with 5 setae and dorsal protruding longest setae (18–25 μm) about 0.6 time of greatest diameter of podomere; tibia nearly1.6–1.9 times longer than wide (45–55 μm, 25–30 μm), with 5 dorsal setae: 3 straight and protruding, 2 slightly curved and depressed, longest setae 0.7–1.0 of greatest diameter of tibia, 2 ventral setae distinctly shorter than dorsal ones; tarsus cylindrical, about 3–4.3 times as long as wide (58–75 μm, 16–19 μm) with 6 dorsal setae: 3 or 4 straight and protruding, others curved and depressed, longest setae (15–22 μm) same with greatest width of podomere, 1 ventral seta close to claw distinctly shorter than dorsal ones. Claws curved, anterior one somewhat broader than posterior one, posterior one more curved than former. Trochanter and femur with cuticular thickenings in pattern of large scales laterally (Fig. 3I). All legs covered with dense pubescence except areas with cuticular thickenings.

Coxal sacs present at bases of legs 3–9, fully developed, each with 4 or 5 setae on surface (Fig. 1H). Corresponding area of leg 2, 10, 11, and 12 replaced by 2–4 setae respectively.

Styli present at base of legs 3–12, slender (length 6–9 μm, width 4–6 μm), basal part with dense straight hairs; distal quarter hairless and with blunt apex (3–5 μm) (Fig. 1H).

Sense calicles located on 2 ventral protuberances of last tergite, posterior to base of leg 12, with smooth margin around pit. Sensory seta inserted in cup center, extremely long (110–140 μm).

Cerci about 0.5–0.6 of head length, 2.5–3 times as long as its greatest width (125–170 μm, 50–63 μm), densely covered with 75–90 subequal setae (Figs 1I–J, 3F–G). Two types of setae inserted on cercus: 7 and 8 long and erect setae located in outer side, and others slightly curved and depressed. Longest outer seta (25–30 μm) 0.4–0.6 of greatest width of cerci (Figs 1J, 3F–G), terminal area short (25–30 μm), circled by 9 layers of curved ridges. Terminal setae (25–32 μm) almost as long as terminal area (Figs 1I, 3F–G).

From the Greek words “macro” meaning “large” and “chaeta” meaning “seta”. The species name “macrochaeta” is feminine and refers to extremely long setae on the frons.

China (Shanghai, Zhejiang).

Symphylella macrochaeta sp. nov. has 10 extremely long macrosetae on the frons, which can distinguish it from all other congeners. It is similar to S. communa from East China and S. asiatica Scheller, 1971 from India and Sri Lanka in the shapes of the central rod, tergites, and leg 12, but the new species differs in the chaetotaxy of the first tergite (4+4 setae in S. macrochaeta sp. nov. and S. communa vs 3+3 setae in S. asiatica) and in the shape of stylus (slender in S. macrochaeta sp. nov. vs subconical in S. communa and conical in S. asiatica). The new species can also be compared to S. macropora from Tibet in the shape of tergites and processes, but it can be easily separated by the shape and the size of the opening of the Tömösváry organ (moderate and round in S. macrochaeta sp. nov. vs large and elongate in S. macropora).

Symphylella longispina sp. nov. is characterized by apparently thickened labrum, distinctly long proximal spines on the pars molaris of the mandible, eight macrosetae arranged as 4/2/2 on the frons, 3+3 setae on the first tergite and narrow triangular processes on tergites.

Holotype : female (slide no. XJ-SY20160003) (SNHM), China, Xinjiang, Bole City, Hariturege National Forest Park, extracted from soil samples from the forest of Populus euphratica, alt. 1125 m, 40°08'N, 81°46'E, 31-VIII-2016, coll. C. W. Huang.

Paratypes : 5 females (slides no. XJ-SY20160001, XJ-SY20160002, XJ-SY20160004, XJ-SY20160005, XJ-SY20160006) (SNHM), same data as holotype.

Adult body 2.4 mm long in average (1.8–2.6 mm, n = 6), holotype 2.4 mm (Fig. 4A).

Head length 210–225 μm, width 190–225 μm, with widest part on equal level of points of articulation of mandibles. Central rod well developed but thin, divided into 2 portions by node-like sub-median interruption, with anterior 48–50 μm and posterior 60–70 μm. (Fig. 4B). Dorsal side of head moderately covered with setae of different lengths. Frons with 5+5 lateral setae, 8 macrosetae (23–28 μm) arranged as 4/2/2 and 2.8–3.7 times as long as antero-central seta (a0) (Fig. 5H), and 16 moderate setae (14–17 μm) (Figs 4B, 5H). Cuticle on anterolateral part of head with coarse granules (Fig. 4B).

Tömösváry organ globular, diameter 12–16 μm, shorter than half of greatest diameter of third antennomere (33–35 μm), opening small and round (4–6 μm), with distinct vertical inner striae (Fig. 4B, E).

Mouthparts . Labrum apparently thickened and protruding (Figs 4C, 5H). Mandible similar to S. macrochaeta sp. nov., but pars molaris with extremely long proximal spines (Figs 4C, 5A). First maxilla has 2 lobes, inner lobe with 6 hook-shaped teeth and pubescent apically, palp pointed and slightly incurved (Fig. 5B). Anterior part of second maxilla with many small protuberances, each carrying 1 seta, distal setae thick; posterior part with sparse setae. Cuticle of second maxilla covered with dense pubescence.

Antennae with 16–20 antennomeres (holotype with 18), about 0.2 of body length. First antennomere cylindrical, almost same as wide as long (width 24–28 μm, length 25–28 μm), with 5–7 setae in 1 whorl, longest inner seta 14–15 μm (Figs 4E, 5C). Second antennomere wider (29–33 μm) than long (24–25 μm), with 8 setae evenly inserted around antennal wall with interior setae (15 μm) slightly longer than exterior ones (11 μm) (Figs 4E, 5C). Chaetotaxy of third antennomere similar to preceding ones. Setae on proximal antennomeres longer and on distal antennomeres shorter. Proximal antennomeres with only primary whorl of setae, in middle and subapical antennomeres with several minute setae in secondary whorl. Four kinds of sensory organs observed on antenna: rudimentary spined sensory organs on dorsal side of most antennomeres except first antennomere (Fig. 5C, D); spined sensory organs only present on terminal antennomere (Fig. 5D, E); cavity-shaped organs on antennomeres 10 and 11 next to apical one, increasing in number to 4 in maximum (Fig. 5D); bladder-shaped organs irregular, round, oval or curved, present on antennomeres 5 and 6 next to apical one increasing in number on subdistal antennomeres to 13 in maximum (Fig. 5D, E). Apical antennomere subspherical, somewhat wider than long (width 25–28 μm, length 15–20 μm), five spined sensory organs consisting of 3 or 4 curved spines around a central pillar and 13–17 setae on distal half (Fig. 5D, E). All antennomeres covered with short pubescence. Chaetotaxy and sensory organs of antennae of holotype are given in Table 4.

Trunk with 17 tergites. Tergites 2–13 and 15 each with 1 pair of triangular processes. Length from base to tip of processes slightly longer than its basal width except for tergites 4, 7, 10 and 13, in which processes almost as broad as long; basal distance between processes of tergites distinctly longer than their length from base to tip (Table 5). All processes with distinct rounded end-swellings (Fig. 4D, F, G). Anterolateral setae of tergites 2, 3, 4, 6, 7, 9 and 10 distinctly longer than other lateromarginal setae, that of tergites 5, 8, 11–13 and 15 subequal or slightly shorter than longest ones of other lateromarginal (Fig. 4D, F, G). Anterolateral setae of tergites shorter than or subequal to process of same tergite. Processes with 1 inserted seta (is) (Fig. 4F). All tergites pubescent (Fig. 4F).

Tergites. Tergite 1 reduced, with 3+3 subequal setae (Fig. 4D). Tergite 2 complete, with 2 triangular posterior processes, 5 or 6 lateromarginal setae, 1 inserted seta, 1 central seta (Table 5), anterolateral setae 0.7–0.8 of length of process, processes 1.1–1.2 times as long as broad, basal distance between processes 1–1.2 times as long as their length (Fig. 4D, F). Tergite 3 complete, broader and longer than preceding one with ratios of 0.7–0.9, 1.1–1.3, and 1.1–1.3 respectively, 7 or 8 lateromarginal setae (Fig. 4D). Tergite 4 broader than tergite 3, with ratios 1–1.2, 0.9–1, and 1.3–1.9 respectively, 5 lateromarginal setae (Fig. 4G). Chaetotaxy of tergites 5–7, 8–10, and 11–13 similar as tergites 2–4. Pattern of alternating tergite lengths of 2 short tergites followed by 1 long tergite only disrupted at caudal end (Table 6). Tergites 14 and 16 without processes and with 15–18 and 10–14 setae respectively. Tergite 17 with 10–14 setae. Chaetotaxy and measurements of tergites are given in Tables 5 and 6.

Legs. First pair of legs reduced to 2 small hairy cupules, each with 1 long seta (9–11 μm) (Fig. 4H). Basal areas of legs 2–12 each with 3–5 setae. Leg 12 about 0.6–0.8 of head length (Fig. 5I), trochanter 1.3–1.6 times longer than wide (45–50 μm, 32–36 μm), with 6 or 7 subequal setae in total; femur almost as long as wide (25–33 μm, 25–30 μm), with 5 setae, longest dorsal seta 17–20 μm in length, pubescent dorsally, laterally with cuticular thickenings in pattern of scales; tibia nearly 1.3–1.9 times longer than wide (28–40 μm, 21–23 μm), with 6 or 7 setae, longest dorsal one 14–18 μm; tarsus subcylindrical, 3–3.5 times as long as wide (45–48 μm, 13–16 μm) with 6 dorsal setae: 4 straight and protruding, 2 slightly curved and depressed, longest setae (14–17 μm) about same length of greatest width of podomere, 2 ventral setae close to claw and distinctly shorter than dorsal ones. Claws curved, anterior one broader than posterior one. All legs covered with dense pubescence except areas with cuticular thickenings.

Coxal sacs present at bases of legs 3–9, fully developed, each with 4 setae on surface. Corresponding area of leg 2, 10, 11 and 12 replaced by 1–3 setae (Fig. 4I).

Styli present at base of legs 3–12, subconical (length 5 μm, width 3 μm), basal part with straight hairs; distal quarter hairless and with blunt apex (3 μm) (Fig. 4I).

Sense calicles with smooth margin around pit. Sensory seta inserted in cup center, extremely long (115–120 μm).

Cerci about half length of head, 3.3–3.8 times as long as its greatest width (108–115 μm, 30–34 μm), sparsely covered with 33–39 subequal setae (Fig. 5F, G). Two types of setae inserted on cercus: 4 or 5 long and erect setae located in outer side, and others slightly curved and depressed. Longest outer seta (20 μm) 0.6–0.7 of greatest width of cerci, terminal area short (16–18 μm), circled by 6–8 layers of curved ridges. Terminal setae (15–16 μm) slightly shorter than terminal area (Fig. 5F, G).

The species name is derived from the Latin words “longus” and “spina” meaning “long spine”. It is feminine and refers to the extremely long proximal spines on the pars molaris of the mandible.

Known only from the type locality.

Symphylella longispina sp. nov. has a thickened and prominent labrum and irregular bladder-shaped organs on antennae, which separate it from all other congeners. It is most similar to S. asiatica Scheller, 1971 from India and Sri Lanka in the shape and chaetotaxy of the tergites, but the new species differs in the distal part of the processes (distinctly swollen in S. longispina sp. nov. vs small and slender in S. asiatica), in the shape and chaetotaxy of cerci (subcylindrical and with sparse setae in S. longispina sp. nov. vs conical and with dense setae in S. asiatica), and in the shape of the palp of the first maxilla (slightly curved in S. longispina sp. nov. vs straight in S. asiatica). The new species is also similar to S. brincki Scheller, 1971 from Sri Lanka in the chaetotaxy of the tergites, but they can be easily separated by the central rod (with a middle node-like interruption in S. longispina sp. nov. vs with a narrow transverse interruption in S. brincki), by the end of the processes (with round end-swellings in S. longispina sp. nov. vs spatulate end-swellings in S. brincki), and by the shape and chaetotaxy of cerci (3.3–3.8 times as long as wide and with sparse setae in S. longispina sp. nov. vs 2.3 times as long as wide and with dense setae in S. brincki).