Samarangopus jacobsoni (Silvestri, 1930).

Fourth antennal segment with 3 well developed setae; globulus of sternal antennal branch g short-stalked; all legs 5-segmented; empodia with 1 anterior accessory claw (Scheller 2011).

Palaearctic, Ethiopian, Oriental, and Australian regions.

Holotype , male adult with 9 pairs of legs (slide no. XZ-PA2015004) (SNHM), China, Tibet, Motuo county, Dexing town, extracted from soil samples in a broad-leaf forest, alt. 1100 m, 29°40'N, 95°26'E, 3-XI-2015, coll. Y. Bu. Paratypes, 5 male adults with 9 pairs of legs (slides no. XZ-PA2015001, XZ-PA2015006, XZ-PA2015052, XZ-PA2015056, XZ-PA2015057) (SNHM), 3 female adults, with 9 pairs of legs (slides no. XZ-PA2015005, XZ-PA2015024, XZ-PA2015054) (SNHM), same data as holotype. Other material, 1 juvenile, with 6 pairs of legs (slides no. XZ-PA2015051) (SNHM), same data as holotype.

Samarangopus zhongi sp. nov. is characterized by one pair of spiniform appendage on sternum of last trunk segment, 28–34 marginal protuberances on tergite I, the distal quarter of bothriotricha T₃ golf-club-shaped, and the leaf-shaped seta st on tergum of pygidium.

Adult body length (0.62–) 0.69 (–0.75) mm (n = 9); body yellow to brown (Figs 1A, 3A).

Head (Figs 1D, 3E) setae strongly reduced, dorsally with first row setae a₁ and 1 pair of lateral setae, other setae absent. Temporal organs rectangular in tergal view, length 0.9 of shortest interdistance, glabrous. Tiny pistils present laterally.

Antennae (Figs 1E, 3C). Chaetotaxy of segments 1–4: 2/2/2(g’)/3. Setae thin, cylindrical, striate, length of seate on segment 4: p =14 (–15) μm, p’ =14 (–17) μm, p’’ =12 (–15) μm; u and r absent. Tergal branch t cylindrical, (2.1–) 2.6 times as wide as greatest diameter and 1.0 (–1.1) times as long as sternal branch. Sternal branch s with distinct anterior indentation at level of F2, 1.9 (–2.3) times as long as greatest diameter, anterodistal corner distinctly truncate. Seta q similar to setae of segment 4, 15 (–17) μm, (0.9 of–) 1.1 times as long as the length of s. Globulus g with conical stalk, length of g (8–10 μm) 1.7 (–1.8) times as long as its greatest diameter; the latter 0.3 (–0.4) of greatest diameter of t; 10 bracts, capsule spherical, diameter = 4–5 μm; stalk length 4–5 μm. Relative lengths of flagella (base segments included): F₁ = 100, F₂ = 48 (–55), F₃ = (78–) 84 (–89). Lengths of base segments: bs₁ = (10–) 12, bs₂ = 5 (–7), bs₃ = 10 (–11) μm. F₁ (4.1–) 4.4 times as long as t, F₂ and F₃ (1.9–) 2.3 and (3.2–) 3.7 times as long as sternal branch s, respectively. Calyces of F₁ largest, conical, those of F₂ and F₃ smaller, subhemispherical.

Figure 1. 

Samarangopus zhongi sp. nov. (holotype) A body, tergal view B tergite I, right side C protuberances on posterolateral corner of tergite I, right side D head, anteriodorsal view E left antenna, tergal view F T₃ G T₅ H setae on coxa (left) and trochanter (right) of leg 9. Scale bars: 20 μm.

Trunk. Setae of collum segment similar, furcate, branches tapering, pointed; main branch striate; secondary branch rudimentary, glabrous; both setae length 10 (–11) μm (Fig. 2A). Appendages barrel-shaped; caps flat (Fig. 2A). Sternite process broad and low, with anterior V-shaped incision. Tergites densely covered with protuberances (Figs 1A–C, 3D, L). Three main types of protuberances observed: large and stalked protuberances present on anterior margin of tergite I and lateral margins of I–VI; smaller fungiform protuberances with transparent hat and subcylindrical foot; small cylindrical cuticular structures with distal candle flame-like vesicle surrounded by circular collar. Cuticles between these structures coarse. Number of marginal protuberances: I, (28–) 34; II, 1 small- T₁-1 small-(9–10); III, 1 small-7- T₂-l small-7; IV, 1 small-(7–8)- T₃-l small-5; V, 1 small-(7–9)- T₄-1small-3; VI, (6–8)- T₅-l. Length/width ratio of tergites: I=0.56 (–0.6), II=0.35 (–0.37), III and IV = 0.38 (–0.43), V = 0.45 (–0.48), V = (0.54–) 0.57 (Fig. 1A). Sternum of last trunk segment with one pair of blunt, spiniform, pubescent posterior appendages (Figs 2B, 3I), 23 (–26) μm in length.

Figure 2. 

Samarangopus zhongi sp. nov. (holotype) A collum segment, sternal view B sternum of the last trunk segment, show spiniform appendages C tergum of pygidum D sternum of pygidum and anal plate E tarsus of leg 1 F tarsus of leg 9 G femur of leg 1 with appendage H male genital papillae. Scale bars: 20 μm.

Bothriotricha. All with thin axes and short almost erect pubescence, T₁, T₂, T₄, and T₅ with distal part curled (Fig. 1G), T₃ shorter than others, with thicker axis and distal quarter flat, golf-club-shaped, densely pubescent (Figs 1F, 3L). Relative lengths of bothriotricha: T₁ = 100, T₂ = (91–) 94, T₃ = (45–) 53, T₄ = (100–) 106, T₅ = 112 (–115).

Legs. All legs 5-segmented. Setae on coxa and trochanter of leg 9 similar to each other, thin, furcate, striate, with glabrous base, length of secondary branch 0.7 (–0.8) of primary one (Figs 1H, 3J). On more anterior legs these setae similar to those of collum segment (Fig. 3G); Tarsi tapering, those of leg 9 (1.9–) 2.5 times as long as greatest diameter; proximal seta striate 11 μm, (0.4–) 0.5 of the length of tarsus (22–28 μm) and (1.7–) 2.0 times as long as distal glabrous seta (5–6 μm) (Figs 2F, 3H). Cuticle of tarsus glabrous (Fig. 3F–H). Tarsus of leg 1 with only glabrous distal seta (Fig. 2E). All legs with large main claw and small setose anterior secondary claw, the former on those of leg 9 0.5 of tarsi. On anterior side of femur of leg 1 with 1 blunt granulated appendage (Figs 2G, 3F).

Figure 3. 

Samarangopus zhongi sp. nov. (holotype) A habitus, sternal view B anal plate C right antenna, sternal view D anterior margin of tergite I E head, tergal view F leg 1, arrow shows appendage on femur G setae on coxa and trochanter of leg 1 H tarsus of leg 9 I last trunk segment, arrows show one pair of appendages, sternal view J setae on coxa and trochanter of leg 9 K male genital papillae and coxa of leg 2 L right side margin of tergite IV and T₃. Scale bars: 100 μm (A); 20 μm (B–L).

Genital papillae (Figs 2H, 3K). Base segments cylindrical. Length of papillae = 25 (–28) μm, greatest diameter =15 (–16) μm, length of seta= 9 (–11) μm. Proximal part of genital papillae subcylindrical, distal part conical, seta 0.4 (–0.5) of length of papilla. Cuticle glabrous. Coxal seta of leg 2 same as on leg 1 (Fig. 3G, K).

Pygidium. Tergum (Fig. 2C). Posterior margin with 2 lateral triangular appendages between a₂ and a₃. Setae annulated, a₁ and a₂ somewhat clavate, the former curved inwards and the latter almost straight; a₃ straight, cylindrical, somewhat tapering, diverging; st leaf-shaped, glabrous. Lengths of setae: a₁= a₂ =5 μm, a₃ = 10 (–12) μm, st = 8 (–9) μm. Distances a₁–a₁=6 (–8) μm, a₁–a₂=5 (–6) μm, a₂–a₃=(4–) 5 μm, st–st=(8–) 10 μm.

Sternum (Fig. 2D). Posterior margin between b₁ straight. Setae thin, tapering, distally striate, pointed. Lengths of setae: b₁= (25–) 28 (–30) μm, b₂=17 (–20) μm, b₃= (11–) 13 μm. Distance b₁–b₁= (26–) 27 μm, b₂–b₂= 45 (–47) μm, b₁–b₂=15 (–16) μm, b₃–b₃= (18–) 20 μm. b₁ 1.0 (–1.3) times as long as interdistance, b₂ (0.9 of–) 1.1 times as long as distance b₁ –b₂, b₃ (0.6–) 0.7 of interdistance.

Anal plate (Figs 2D, 3B) (2.1–) 2.2 times as long as broad, tapering posteriorly; lateral margins with a pair of thin, diverging, cylindrical, distal part faintly inflated, pubescent branches which are (0.3–) 0.4 of the length of plate; posterior 2/5 of plate divided into 2 tapering branches by a narrow V-shaped incision, each branch with 2 appendages: a submedian short, straight, tapering, glabrous one and a stalked bladder of triangular shape in sternal view. Bladder-shaped appendages (0.6–) 0.7 of length of plate. Plate glabrous, bladder-shaped appendages with short erect pubescence.

The new species is dedicated in honor of the late Professor Zhong Yang (1964–2017) who was an eminent botanist from Fudan University and Tibet University, for his great contribution to the knowledge of flora and biodiversity of Tibet. This study is also to express my great gratitude to his help.

Known only from the type locality.

Samarangopus zhongi sp. nov. can be easily distinguished from all other congeners by the presence of the one pair of spiniform appendages on the sternal side of last trunk segment. It is most similar to S. campanulatus Scheller, 2004 from Vietnam in the shape of anal plate, the chaetotaxy of pygidium and the protuberances on the body. It can be distinguished from S. campanulatus by: the spiniform appendages on the sternum of last trunk segment (present in S. zhongi sp. nov. vs absent in S. campanulatus), shape of bothriotricha T₃ (distal quarter golf-club-shaped, densely pubescent in S. zhongi sp. nov. vs distal 2/5 part clavate, end-swelling in S. campanulatus), shape of seta st on tergum of pygidium (leaf-shaped in S. zhongi sp. nov. vs lanceolate in S. campanulatus), the shape of proximal seta on tarsus 9 (striated in S. zhongi sp. nov. vs glabrous in S. campanulatus), and the shape of appendage on the femur of leg 1 (broad triangular in S. zhongi sp. nov. vs blunt cylindrical in S. campanulatus) . The shape of posterior appendage on anal plate of the new species is also similar to S. tuberosus Scheller, 2007 from Singapore and S. cylindratus Scheller, 2009 from Indonesia. The new species differs from S. tuberosus in the shape of setae b₂ on pygidium (slender and pointed in S. zhongi sp. nov. vs large and lanceolate in S. tuberosus). It differs from S. cylindratus in the shape of appendages of the collum segment (barrel-shaped in S. zhongi sp. nov. vs cylindrical and large in S. cylindratus).

1 male adult with 9 pairs of legs (slide no. XZ-PA2015053) (SNHM), 1 female adult with 9 pairs of legs (slide no. XZ-PA2015055) (SNHM), China, Tibet, Motuo county, Dexing town, extracted from soil samples of broad-leaf forest, Alt. 1100 m, 29°40'N, 95°26'E, 3-XI-2015, coll. Y. Bu.

Samarangopus canalis Scheller, 2009 is characterized by the peculiar shape of distal part of male genital papillae which forming an anteriorly open furrow and the ovoid posterior appendages of the anal plate.

Length 0.90 mm (n = 2), yellow to brown in color (Fig. 4A). Head covered by tergite I and chaetotaxy not studied in detail.

Antennae (Fig. 4B). Chaetotaxy of segments 1–4: 2/2/2/3. Setae thin, cylindrical, striate, length of seate on segment 4: p = 16–18 μm, p’ = 15–17 μm, p’’ = 10–12 μm; p’’’ rudimentary; u and r absent. Tergal branch t fusiform, 2.9–3.2 times as wide as greatest diameter and 1.2–1.3 times as long as sternal branch. Sternal branch s with distinct anterior indentation at level of F₂, 1.8–2.0 times as long as greatest diameter, anterodistal corner distinctly truncate. Seta q similar to setae of segment IV, 15–16 μm, 0.8 of the length of s. Globulus g with conical stalk, length of g (10–12 μm) 1.7–2.0 times as long as greatest diameter; the latter 0.2–0.3 of greatest diameter of t; 9–10 bracts, capsule spherical, diameter = 3 μm; stalk length 5 μm. Relative lengths of flagella (base segments included): F₁ = 100, F₂ = 35–40, F₃ = 82–84. Lengths of base segments: bs₁ = 15–18 μm, bs₂ = 7–8 μm, bs₃ = 13–14 μm. F₁ 3.3–3.7 times as long as t, F₂ and F₃ 1.6–1.9 and 3.6–3.9 times as long as sternal branch s. Calyces of F₁ largest, conical, those of F₂ and F₃ smaller, subhemispherical.

Trunk. Setae of collum segment similar, furcate, branches tapering, pointed; main branch cylindrical, annulated, blunt, secondary branch 0.3 of the length of primary branch, glabrous (Fig. 4C); submedian seta 0.8–0.9 of the length of sublateral seta. Sternite process broad and low, with anterior incision and rounded pubescent lobes. Appendages subcylindrical, caps flat. Process and appendages glabrous. Tergites densely covered with protuberances. Anterior and lateral margins of tergites with a single row of large protuberances (Fig. 4A, E, F). Posteriomedian margin of tergites with comb-shaped ornaments (Fig. 4G). Number of marginal protuberances: I, 26–29; II, 1 small- T₁-1 small-9; III, (5–6)- T₂-l small-6; IV, (6–7)- T₃-l small-5; V, 8- T₄-l small-3; VI, 6- T₅-l. Length/width ratio of tergites: I = 0.67–0.72, II = 0.34–0.36, III and IV = 0.42–0.45, V = 0.44–0.46, VI = 0.56–0.59.

Bothriotricha. All with thin axes, glabrous proximal parts, distally with minute pubescence, T₁, T₂, T₄ and T₅ curled distally, T₃ shorter than others, with thicker axis and terminated by an ovoid swelling (Fig. 4E). Relative lengths of bothriotricha: T₁ = 100, T₂ = 94, T₃ = 56, T₄ = 94, T₅ = 100.

Genital papillae (Fig. 4D). Base segments in the shape of a truncated cone, relatively long, length of papillae 65 μm, greatest diameter 20 μm, seta 55 μm. Proximal part of papillae strongly tapering outward, distal 3/4 forming an anteriorly open furrow. Papilla 3.3 times as long as greatest diameter, seta 0.8 of length of papilla. Cuticle glabrous. Coxal seta of leg 2 in male with long base, furcate, primary branch cylindrical, annulated, secondary branch short, tapering, pointed, glabrous.

Legs. All legs 5-segmented. Setae on coxa and trochanter of leg 9 similar to each other, thin, furcate, densely annulated, length of secondary branch 0.7–0.8 of primary one (Fig. 4I). On more anterior legs these setae with rudimentary secondary branches (Fig. 4H). Tarsi of leg 9 short and thick, tapering, 2.2 times as long as greatest diameter; tergal setae pointed, glabrous. Proximal seta length 9–10 μm, 0.3 of the length of tarsus (33 μm) and 1.2–1.3 times as long as distal seta (7–8 μm). Cuticle of tarsus with minute granules. No proximal seta on tarsus of leg 1. All legs with large main claw and small setose anterior secondary claw, the former on those of leg 9 0.5 of tarsi. Anterior side of femur of leg 1 with one blunt appendage with short pubescence, length = 4–5 μm (Fig. 4H).

Figure 4. 

Samarangopus canalis Scheller, 2009 (Chinese specimens) A habitus, tergal view B left antenna, tergal view C collum segment, sternal view D male genital papillae E right margin of tergite IV, show T₃ F right anterolateral corner of tergite II, tergal view G posteriomedian margin of Tergite I H leg 1 I setae on coxa and trochanter of leg 9. Scale bars: 100 μm (A); 20 μm (B–I).

Pygidium. Tergum. Posterior margin with two narrow, digitiform posterior directed processes protruding from between setae a₂ and a₃. Setae glabrous, a₁ straight, a₂ clavate, short, a₃ slender and long; st long and leaf-shaped, 10–11 μm. Two semicircle plates close to st with dense pubescence. Lengths of setae: a₁= 5 μm, a₂ =6–8 μm, a₃ = 15 μm. Distance a₁–a₁=7–9 μm, a₁–a₂=5–7 μm, a₂–a₃=4–5 μm, st–st=10 μm.

Sternum. Posterior margin between b₁ almost straight. Setae thin, tapering, pointed, distal part of b₁ annulated, b₂ and b₃ striated. Lengths of setae: b₁= 32 μm, b₂=23–25 μm, b₃= 11–13 μm. Distances b₁–b₁= 28–30 μm, b₂–b₂= 50–53 μm, b₁–b₂= 21–23 μm, b₃–b₃= 23–25 μm. b₁ 1.1 times as long as interdistance, b₂ 1.0–1.2 of distance b₁ –b₂, b₃ 0.55 of interdistance.

Anal plate. 1.2 times as long as broad; lateral margins straight anteriorly, concave posteriorly; distal part of plate cleft by narrow U-shaped incision, depth 0.3–0.4 of the length of plate, incision forming two posterior branches with subparallel sides, each with two appendages: a submedian short, straight, glabrous one and a thin folioform stalked appendage protruding backward. Folioform appendage about 0.6 of length of plate. Plate glabrous, distal appendages with somewhat granular surface.

China (Tibet), Indonesia (Sulawesi).

Samarangopus canalis was originally described and only known from Sulawesi Island, Indonesia (Scheller 2009). The anal plate, the male genital papillae as well as the protuberances on the body of Chinese specimens are nearly the same with S. canalis which proved the species identity. The main difference is that the posterior branches of anal plate of Chinese specimens each have two appendages, with a submedian, short, straight, glabrous appendage present, but absent in the types from Sulawesi. Other minor differences are the body size, numbers of protuberances on the body and the lengths of setae, bothriotricha, and flagella, which might belong to the variances between populations of different localities. In addition, the anal plate of S. canalis and S. zhongi sp. nov. both having two appendages, but the shape of posterior one is different: bladder is triangular in S. zhongi sp. nov. but folioform in S. canalis.