Central rod on head broken and distinct in both anterior and posterior portions. Antennae with 14–22 segments. Trunk with 17 tergites or fewer, with the first tergite vestigial. Triangular processes present on posterior margins of 13 tergites. Belts of longitudinal striae between processes absent. First pair of legs vestigial, as small protuberances with a few setae. Styli rudimentary. Coxal plates with sacs only present on 3^rd–9^th legs. Cerci relatively long, terminal area with transverse stripes, ending in a single long seta (Bagnall 1913; Szucsich and Scheller 2011).

The genus Symphylella currently includes 47 extant subcosmopolitan species (Szucsich and Scheller 2011; Jin and Bu 2018). It has previously been recorded from China, but the species have never been identified (Zhang and Wang 1992).

Symphylella macropora sp. n. is characterized by large, elongated oval openings of the Tömösváry organs, with their inner margins of these openings covered by minute irregular teeth, as well as by having rudimentary spined sensory organs on the dorsal side of most antennal segments, and cerci with numerous long and slightly curved setae.

Holotype, female (slide no. XZ-SY2015030) (SNHM), China, Tibet, Motuo county, Dexing town, extracted from soil samples from broadleaf forest, alt. 1100 m, 29°40'N, 95°26'E, 3-XI-2015, coll. Y. Bu & G. Yang. Paratypes, 6 females (slides nos. XZ-SY2015023–XZ-SY2015026, XZ-SY2015029, XZ-SY2015032) (SNHM), 3 males (slides nos. XZ-SY2015027, XZ-SY2015028, XZ-SY2015031) (SNHM), same date as holotype; 1 female (slide no. XZ-SY2015034) (SNHM), China, Tibet, Motuo county, Beibeng town, extracted from soil samples from broadleaf forest, alt. 1500 m, 29°30'N, 95°38'E, 5-XI-2015, coll. Y. Bu & G. Yang. Other materials (SNHM): 1 juvenile with 9 pairs of legs (slide no. XZ-SY2015033) (SNHM), China, Tibet, Motuo county, Beibeng town, extracted from soil samples from broadleaf forest, alt.1500 m, 29°30'N, 95°38'E, 5-XI-2015, coll. Y. Bu & G. Yang; 2 juveniles with 9–10 pairs of legs (slides nos. XZ-SY2015035–XZ-SY2015036) (SNHM), same date as holotype; 10 juveniles with 8–10 pairs of legs (slides nos. XZ-SY2015037–XZ-SY2015046) (SNHM), China, Tibet, Motuo county, Dexing town, Naerdong village, extracted from soil samples from broadleaf forest, alt. 1800 m, 29°30'N, 95°23'E, 4-XI-2015, coll. Y. Bu.

Adult body 1.90 mm long in average (1.55–2.71 mm, n=11), holotype 1.89 mm (Fig. 1A).

Head length 210–270 μm, width 225–300 μm, with widest part somewhat behind the middle on a level with the points of articulation of mandibles. Central rod distinct in both anterior (50–70 μm) and posterior (58–75 μm) portions, with a middle knot. Anterior branches well developed, median branches vestigial. Head dorsally moderately covered with setae of different length, longest setae (25–35 μm) located most anteriorly, at least 3.0 times as long as central ones (8–12 μm). Cuticle at anterolateral part of head with rather coarse granulation. Tömösváry organ surrounded by fine granulation, other areas with fine dense granulation (Fig. 1D).

Tömösváry organ oval, length 19–32 μm, width 10–22 μm, at least half of greatest diameter of 3^rd antennal segment (35–50 μm), openings large and elongated oval (length 13–26 μm, width 5–10 μm), with their inner margins covered by minute irregular teeth (Figs 1C, 1D).

Mouthparts Mandible with two fused lamellae and 11 teeth in total (Fig. 2A). First maxilla with two lobes, inner lobe with four hook-shaped teeth, palp bud-like with 1 distal point close to outer lobe (Fig. 2B). Anterior part of second maxilla with many small protuberances which carry one seta each, distal setae thickened; posterior part with sparse setae. Cuticle of maxilla and labium covered with pubescence.

Antennae with 16–23 segments (18 in holotype), length 570–680 μm (620 μm in holotype), about 0.3 of body length. 1^st segment cylindrical, much shorter than following ones, greatest diameter wider than long (37–45 μm, 13–33 μm), with 2–3 microsetae and 6–9 long mesosetae in one whorl, longest seta (20–24 μm) inserted at inner side and distinctly longer than outer ones (15–18 μm). 2^nd segment wider (35–44 μm) than long (28–35 μm), with eight or nine setae evenly inserted around antennal wall, interior setae (23–26 μm) slightly longer than exterior ones (16–19 μm). Chaetotaxy of 3^rd segment like preceding ones. Setae on basal segments slender and on distal segments shorter. Basal segments of antennae with only primary whorl of setae, in middle and subapical segments with several minute setae in secondary whorl. Three kinds of sensory organs on most antenna segments: rso on dorsal side of most segments (Figs 2C, 2E); co on dorsal side of 3^rd–21^th segments; bo on subapical 5–9 segments (Figs 1B, 2C, 2D). Apical segment subspherical, somewhat wider than long (width 28–32 μm, length 24–26 μm), with 13–15 setae on distal half and 2 baculiform organs on apex, 4–7 so consisting of 3–4 curved spines around a central pillar in depressions in distal surface (Figs 2C, 2D). All segments covered with short pubescence. Chaetotaxy and sensory organs of antennae are given in table 1.

Trunk with 17 tergites. Most tergites overlap, with intertergal zones present between adjacent tergites, except for borders between 14^th and 15^th, as well as 16^th and 17^th tergite. Tergites 2–13, and 15 each with one pair of triangular processes. Basal distance between processes of 4^th–13^thand 15^th tergites longer than their length from base to tip, and the latter shorter than its basal wide (Table 2). Anterolateral setae of 2^nd, 3^rd, 4^th, 6^th, 7^th, 9^th and10^th tergites distinctly longer than other lateromarginal setae, that of 5^th, 8^th, 11^th–13^th and 15^th subequal or slightly longer than other lateromarginal setae. Triangular processes without ovoid swollen ends (Fig. 1G). One to three inserted setae (setae between inner basal seta and apical seta). All tergites pubescent.

Tergites 1^st tergite reduced and build up of two short plates separated in the median axis of the body, with 6–9 short setae in a row. 2^nd tergite complete, with two posterior processes, 5–8 lateromarginal setae, 1–2 inserted setae, 1–4 central setae, with anterolateral setae distinctly longer than other lateromarginal setae, processes approximately 0.9 times as long as broad, basal distance between processes approximately 0.7 times as long as their length. 3^rd tergite entire, broader and longer than preceding one with ratios mentioned nearly the same as for the 2^nd tergite, 6–10 lateromarginal setae (Fig. 1H). 4^th tergite broader than 3^rd tergite, with ratios approximately 0.7 and 1.4 respectively, 5–7 lateromarginal setae (Fig. 1I). Shape and chaetotaxy of 5^th–7^th, 8^th–10^th, and 11^th–13^th tergite similar as 2^nd–4^th tergite. 15^th tergite shorter with smaller processes than remaining long tergites (3^rd, 6^th, 9^th and 12^th tergites). 14^th and 16^th tergites without processes, with 11–17 and 6–14 marginal setae respectively (Fig. 1J). 17^th tergite with 20–31 setae. Chaetotaxy and measurements of tergites are given in Table 2, 3.

Legs 1^st pair of legs reduced to two small hairy cupules, each with two long setae (Fig. 1E). Basal areas of legs 2–12 each with 4–6 setae (Fig. 1F). Leg 12 about 0.1 time as long as body, subequal length with head. Trochanter longer than wide (52–76 μm, 40–56 μm) with 6–8 subequal setae. Femur as long as wide (32–42 μm, 30–41 μm), with 4–6 setae and one of them (17–28 μm) distinctly longer than others (10–20 μm); pubescent dorsally, ventrally with cuticular thickenings in pattern of large scales. Tibia nearly 2 times longer than wide (40–60 μm, 23–30 μm), with 5–7 dorsal setae and the longest one slightly shorter than greatest diameter of tibia (19–28 μm).Tarsus subcylindrical, at least 3 times as long as wide (50–70 μm, 15–20 μm), with 6–9 setae: 3 straight and protruding, 2 curved and depressed; longest setae (20–27 μm) about same length of greatest width of podomere, and 2 ventral setae inserted near claw distinctly shorter than dorsal ones. Claws rather curved, anterior one distinctly longer and broader than posterior one, the latter more curved than the former (Fig. 2F). All legs covered with dense pubescence except areas with cuticular thickenings.

Coxal sacs present at bases of 3^rd–9^th pairs of legs, fully developed, each with 4 setae on its surface (Fig. 1F).

Styli present at base of 3^rd–12^th pairs of legs, subconical (length 6–9 μm, width 4–6 μm), basal part with straight hairs; distal one fourth hairless and blunt (3–6 μm) (Figs 1F, 2G).

Sense calicles with smooth margin to pit, length about the same as outer diameter (18–39 μm, 20–35 μm). Sensory seta inserted in cup center, extremely long, length 130–165 μm, at least 5.5 times longer than other two lateral setae (20–35 μm, 14–22 μm respectively) that inserted at the edge of cup.

Cerci subuliform, short, about 0.6 of head length and leg 12, length at least three times as long as its greatest width (126–172 μm, 40–53 μm), moderately covered with subequal length and slightly curved setae, with longest (20–40 μm) at least half of the greatest width of the cerci, terminal area (23–32 μm) short, circled by 6–8 layers of curved ridges. Terminal setae length 18–28 μm (Fig. 2H).

The species name macropora is referring to the large opening of the Tömösváry organ.

Known only from the type locality.

Symphylella macropora sp. n. is most similar to S. javanensis Scheller, 1988 from Java in the shape of tergites and processes, leg 12 and sensory organs on antennae. However, it can be readily distinguished from the latter by the shape of Tömösváry organ (oval, openings large and elongated with inner margins covered by minute irregular teeth vs subspherical, diameter of opening about half of the organ in S. javanensis), central rod (both anterior and posterior portions distinct in S. macropora sp. n. vs anterior half and anterior branches very thin with traces in S. javanensis), and the stylus (with blunt apex in S. macropora sp. n. vs with truncate apex in S. javanensis). It is also closely related to S. asiatica Scheller, 1971 from Indiaand Sri Lanka in the shape and chaetotaxy of tergites 1–3, leg 12 and the sensory organs on antenna, but easily distinguished by characters of Tömösváry organ (openings very small in S. asiatica), and the cerci (most setae subequal length and slightly curved in S. macropora sp. n. vs long and erect setae on dorsal, ventral and outer sides arranged in one or two rows in S. asiatica).

Symphylella zhongi sp. n. is characterized by a globular Tömösváry organ with small and roundish opening, processes on tergites mostly longer than their basal width, ovoid swollen ends of processes, and mushroom-shaped sensory organs present on apical antennal segments.

Holotype, female (slide no. XZ-SY2015049) (SNHM), China, Tibet, Linzhi City, Bomi county, Songzong town, extracted from soil samples from broadleaf forest, alt. 3000 m, 29°76'N, 95°96'E, 7-XI-2015, coll. Y. Bu & G. Yang. Paratypes, 2 females (slides nos. XZ-SY2015047–XZ-SY2015048) (SNHM), same date as holotype. Other materials: 3 juvenile with 8 or 9 pairs of legs (slides nos. XZ-SY2015050–XZ-SY2015052) (SNHM), same date as holotype.

Adult body 2.48 mm long on average (2.22–2.93 mm, n = 3), holotype 2.93 mm (Fig. 3A).

Head length 250–262 μm, width 262–287 μm, with widest part somewhat behind the middle on a level with the points of articulation of mandibles. Central rod distinct in both anterior (65–70 μm) and posterior (75–90 μm) portions, with a middle knot. Anterior branches well developed, median branches vestigial. Dorsal side of head moderately covered with setae of different length, longest setae (27–35 μm) located most anterior on head, at least 3.0 times as long as central ones (8–11 μm). Cuticle at anterolateral part of head with rather coarse granulation. Tömösváry organ surrounded by fine granulation, other area with faint dense granulation (Fig. 3D).

Tömösváry organ globular, length19–24 μm, width 16–22 μm, about half of greatest diameter of 3^rd antennal segments (40–42 μm), opening small and roundish (length 8 μm, width 3–6 μm) (Figs 3C, D).

Mouthparts. Mandible with two fused lamellae and 11 teeth in total (Fig. 4A). First maxilla has two lobes, inner lobe with four hook-shaped teeth, palp bud-like with one distal point close to outer lobe (Fig. 4B). Anterior part of second maxilla with many small protuberances which carry one seta each, distal setae more thick and hard; posterior part with sparse setae. Cuticle of maxilla and labium covered with pubescence.

Antennae with 18–23 segments (left antenna with 19, right antenna with 21 in holotype), length 513–663 μm (663 μm in holotype), about one fourth of body length. 1^st segment cylindrical, greatest diameter somewhat wider than long (40–42 μm, 23–40 μm), with 1 or 2 microsetae and 6 or 7 mesosetae in one whorl, longest seta (20–22 μm) inserted at inner side and distinctly longer than outer ones (14–15 μm). 2^nd segment wider (25–28 μm) than long (40 μm), with 7 or 8 setae evenly inserted around the antennal wall with interior setae (20–21 μm) slightly longer than exterior ones (14–15 μm). Chaetotaxy of 3^rd segment similar to preceding ones. Setae on basal segments longer and on distal segments shorter. Basal antennae segments with only primary whorl of setae, in middle and subapical segments several setae in secondary whorl. Four kinds of sensory organs on antenna: rso on dorsal side of most segments (Figs 4C, E); co on 7^th–19^th segments; bo on 9–11 segments next to apical one increasing in number on subdistal segments to a maximum of 21 (Figs 3B, 4C); mo on distal 2 segments (Fig. 4C). Apical segment subspherical, somewhat longer than wide (width 24–27 μm, length 32–35 μm), with 15–18 setae on distal half; 3–5 spined sensory organs consisting of 3 or 4 curved spines around a central pillar in depressions in distal surface; 2 baculiform organs on apex of segment (Figs 4C, D). All segment covered with short pubescence. Chaetotaxy and sensory organs of antennae are given in Table 4.

Trunk with 17 dorsal tergites. Most tergites overlap, with intertergal zones present between adjacent tergites, except for borders between 14^th and 15^th, as well as 16^th and 17^th tergite. Tergites 2–13 and 15 each with one pair of triangular processes. Length from base to tip of processes somewhat longer than its basal width except for the 4^th, 7^th, 10^th and 13^th tergites, where processes are broader than long; basal distance between processes of 4^th–13^th and 15^th tergite longer than their length from base to tip (Table 5). Triangular processes with ovoid swollen ends (Fig. 3I). Anterolateral setae of 2^nd, 3^rd, 4^th, 6^th, 7^th, 9^th and10^th tergite distinctly longer than other lateromarginal setae, that of 5^th, 8^th, 11^th –13^th and 15^th subequal or slightly longer than other lateromarginal. One to two inserted setae. All tergites pubescent.

Tergites. 1^st tergite reduced and build up of two short plates separated in the median axis of the body, with 8 short setae in a row. 2^nd tergite complete, with two slender posterior processes, 6–8 lateromarginal setae, 1 or 2 inserted setae, 2 central setae, with anterolateral setae distinctly longer than other lateromarginal ones, processes approximately 1.1 times as long as broad, basal distance between processes approximately 0.8 times as long as their length (Fig. 3E). 3^rd tergite complete, broader and longer than preceding one with ratios of 1.1 and 0.9 respectively, 8 or 9 lateromarginal setae (Fig. 3F). 4^th tergite broader than 3^rd tergite, with ratios approximately 0.8 and 1.5 respectively, 6 or 7 lateromarginal setae (Fig. 3H). Chaetotaxy of 5^th–7^th, 8^th–10^th, and 11^th–13^th tergites similar to 2^nd–4^th tergites. Pattern of alternating tergite lengths of two short tergites followed by a long tergite only disrupted at the caudal end (Table 5). Within short tergites (1, 2, 4, 5, 7, 8, 10, 11, 13, 14, 16) the length augments toward caudal. Same is generally true for long tergites (3, 6, 9, 12, 15, 17), but for the 15^th tergite being shorter than the others, with likewise smaller processes. 14^th and 16^th tergite without processes with 13–18 and 10–15 marginal setae respectively (Fig. 3J). 17^th tergite with 32–44 setae. Chaetotaxy and measurements of tergites are given in Tables 5 and 6.

Legs. 1^st pair of legs reduced to two small hairy cupules, each with two long setae (Fig. 3G). Basal areas of legs 2–12 each with 5–7 setae. Leg 12 about 0.1 times the length of the body, about same length like head. Trochanter distinctly longer than wide (70–83 μm, 40–50 μm), with 7 or 8 subequal setae. Femur as long as wide (38–43 μm, 35–40 μm), with 5 setae and one of them (22 μm) distinctly longer than others (12–18 μm); trochanter and femur pubescent dorsally, ventrally with cuticular thickenings in pattern of large scales. Tibia nearly 2 times longer than wide (50–60 μm, 27–30 μm), with 6 dorsal setae and longest one nearly the same length as greatest diameter of tibia (21–30 μm). Tarsus subcylindrical, about 3.5 times as long as wide (68–75 μm, 20 μm) with 5 dorsal setae: 3 straight and protruding, 2 curved and depressed; longest setae (20–22 μm) about same length of greatest width of podomere; 2 ventral setae inserted near claw distinctly shorter than dorsal ones. Claws curved, anterior one somewhat longer and broader than posterior one, the latter more curved than the former (Fig. 4G). All legs covered with dense pubescences except areas with cuticular thickenings.

Coxal sacs present at bases of 3^rd–9^th pairs of legs, fully developed, each with 4 setae on surface (Fig. 3G).

Styli present at base of 3^rd–12^th pairs of legs, subconical (length 5–8 μm, width 3–4 μm), basal part with straight hairs; distal quarter hairless and blunt (3–4 μm) (Figs 3G, 4F).

Sense calicles with smooth margin to pit, about same length as outer diameter (28–30 μm, 26–30 μm). Sensory seta inserted in cup center, extremely long, length 170–180 μm, at least 5.5 times longer than other two lateral setae (20–24 μm, 13–20 μm respectively) inserted at edge of cup.

Cerci subuliform, about 0.7 of head length and leg 12, length at least three times as long as its greatest width (150–188 μm, 45–58 μm), moderately covered with subequal length and slightly curved setae, with longest (25–28 μm) at least half of greatest width of cerci, terminal area (24–28 μm) short, circled by 6–8 layers of curved ridges. Terminal setae length 25 μm (Fig. 4H).

We dedicate this new species in honor of the late Professor Zhong Yang (1964–2017) who was an eminent botanist from Fudan University, for his great contribution to the knowledge of flora and biodiversity of Tibet.

Known only from the type locality.

Symphylella zhongi sp. n. is most similar to S. multisetosa Scheller, 1971 in the shape of the Tömösváry organ, as well as the shape and chaetotaxy of the tergites 1–4, 1^st leg, but it deviates distinctly in the shape of the ends of the processes (with ovoid swollen ends in S. zhongi sp. n. vs without ovoid swollen ends in S. multisetosa), chaetotaxy of the cerci (most setae subequal length and slightly curved in S. zhongi sp. n. vs long, straight, erect setae on dorsal, ventral, and outer sides of cerci arranged in one or two rows in S. multisetosa). It is also similar to S. simplex (Hansen, 1903) in the shape and chaetotaxy of first two tergites, sensory organs of antennal segments and 1^st leg, but differs in the shape of 1^stantennal segment (moderate in S. zhongi sp. n. vs very short in S. simplex), chaetatoxy of 3^rd tergite (8 or 9 lateromarginal setae in S. zhongi sp. n. vs 11 or 12 in S. simplex) and 4^th tergite (6 or 7 lateromarginal setae in S. zhongi sp. n. vs 8 in S. simplex), chaetotaxy of cerci (8–10 longish setae protruding, others short and depressed in S. simplex).

The new species is compared with similar species in Table 7.

The 43 species of the genus Symphylella can be distinguished by the following key, but six species (Symphylella natala Hilton, 1938, Symphylella vaca Hilton, 1938, Symphylella elongata Scheller, 1952, Symphylella foucquei Jupeau, 1954, Symphylella maorica Adam & Burtel, 1956, and Symphylella sp. Rochaix, 1956), which have very brief original descriptions, are not included.