Samarangopus testudineus, Gao & Bu, 2023

Gao, Yan & Bu, Yun, 2023, Two new species of the genus Samarangopus and the first record of Eurypauropus japonicus (Arthropoda, Myriapoda, Pauropoda, Eurypauropodidae) from China, ZooKeys 1165, pp. 137-154 : 137

Samarangopus testudineus sp. nov.

Figs 1 , 2 , 3 , 4

Material examined.

Holotype, female adult with 9 pairs of legs (slide no. HN-SHS-PA2020035) (SNHM), China, Hunan Province, Shaoyang City, Xinning County, Shunhuangshan Nature Reserve , extracted from soil samples in mixed forest, elev. 900 m, 26°23'N, 111°00'E, 4-IX-2020, coll. C.W. Huang. Paratype, 1 juvenile with 8 pairs of legs (slide no. HN-NS-PA2020036), Hunan Province, Shaoyang City, Chengbu County, Nanshan National Park , extracted from soil samples in mixed forest, elev. 1200 m, 26°18'N, 110°29'E, 8-IX-2020, coll. C.W. Huang.

Diagnosis.

Samarangopus testudineus sp. nov. is characterized by testudinal pattern (tortoise shell-like) on the dorsal side of the body, marginal protuberances on tergites well-differentiated into four kinds of shapes, and one pair of sausage-shaped bladders on the anal plate.

Description.

Adult body length 1.95 mm; body dark brown in alcohol, brown to reddish after mounted on slides, dorsally with distinct testudinal pattern (Figs 1A, B , 2A ).

Head setae strongly reduced, dorsally with setae a 0 and one pair of lateral setae l 1, other setae absent. Temporal organs rectangular in tergal view, length 0.7 of shortest interdistance, glabrous. Tiny pistils present laterally.

Antennae (Fig. 2B ). Chaetotaxy of segments 1-4: 2/2/3/3. Setae thin, cylindrical, striate, length of setae on segment 4: p = 40 μm, p ' = 35 μm, p ″ = 30 μm; u and r absent. Third antennal segment with two normal setae and one rudimentary pin-shaped seta. Tergal branch t cylindrical, 4.6 times as long as greatest diameter and 1.1 times as long as sternal branch s, the latter with distinct anterior indentation at level of F 2, 3.2 times as long as greatest diameter. Seta q similar to setae of segment 4, 30 μm, 0.5 times of length of s. Globulus g with conical stalk, length of g (11 μm) 1.4 times as long as its greatest diameter; the latter 0.2 times of greatest diameter of t; 10 bracts, capsule spherical, diameter = 8 μm; stalk length 5 μm. Relative lengths of flagella (base segments included): F 1 = 100, F 2 = 55, F 3 = 89. Lengths of base segments: bs 1 = 20 μm, bs 2 = 13 μm, bs 3 = 18 μm. F 1 3.1 times as long as t, F 2 and F 3 1.8 and 3.0 times as long as sternal branch s, respectively. Calyces of F 1 largest, those of F 2 and F 3 smaller, all subhemispherical.

Trunk. Collum segment not clearly visible. Tergites with testudinal patterns limited by different kind of structures and protuberances (Figs 1A, B , 2A ). Vertical wide ridges composed by long, candle-like protuberances located on tergites I-V medially, transverse narrow ridges composed by short, candle-like protuberances and conical protuberances located on tergites II-V (Figs 2F , 3D ). Posterior margin of tergites comb-shaped with tiny granules on it (Fig. 3C ). Cuticles between these structures coarse (Fig. 3D, G ). Marginal protuberances well differentiated with different shapes: (1) conical on anterior margin and posterior corner of tergite I (Figs 2D , 3A ); (2) pointed leaf-shaped with reticulations on posterolateral margin of tergite I and lateral margin of other tergites (Figs 2C-E , 3B, E, F, G ); (3) one rounded leaf-shaped on the posterior corner of tergite II-V (Figs 2E , 3E, G ); (4) tiny, rod-shaped on anterior corner of each tergite and behind cavities of bothriotricha of tergites II-V (Figs 2E , 3E, G ). Pattern of marginal protuberances: tergite I: 1 tiny-3 large-41 small-3 large-1 tiny; tergite II: 1 small-1 tiny- T 1-10 large; tergite III: 1 small-7 large-1 tiny- T 2-6 large; tergite IV: 1 small-8 large-l tiny- T 3-5 large; tergite V: 1 small-(8-10) large-1 tiny- T 4-4 large; tergite VI: 1 small-(7-8)- T 5-2 large. Length/width ratio of tergites: I = 0.58, II = 0.26, III = 0.30, IV = 0.29, V = 0.32, and VI = 0.58.

Bothriotricha . All with short pubescence, T 1, T 2, T 4, and T 5 thin and with blunt apex (Fig. 4C, E ), T 3 shorter than others, with thicker axis, distal part spatulate, and densely pubescent (Fig. 4D ). Relative lengths of bothriotricha: T 1 = 100, T 2 = 92, T 3 = 75, T 4 = 96, T 5 = 81.

Legs. All legs 5-segmented. Setae on coxa and trochanter of leg 9 similar to each other; thin, glabrous, bifurcate, with length of secondary branch 0.6 times of primary one (Fig. 4I ). Tarsi tapering, those of leg 9 1.9 times as long as greatest diameter; proximal seta glabrous, pointed, 35 μm, 0.4 times of the length of tarsus (75 μm) and 2.9 times as long as distal pubescent seta (12 μm) (Fig. 4G ). Tarsus of leg 1 with only pubescent distal seta (Fig. 4F ). Setae on coxa and trochanter of leg 1 both bifurcate, glabrous, length of secondary branch 0.2 times of primary one (Fig. 4H ). All legs with large main claw and small setose anterior secondary claw (Fig. 4F, G ).

Pygidium. Tergum (Fig. 4B ). Setae pubescent: a 1 and a 2 short, clavate, the former curved inwards; a 3 straight, cylindical. Three pubescent appendages of irregular shape: two lateral triangular appendages between a 2 and a 3, one medial appendage at posterior margin, located posterior to Setae a 1. Lengths of setae: a 1 = 12 μm, a 2 = 13 μm, a 3 = 28 μm. Distances a 1- a 1 = 13 μm, a 1- a 2 = 12 μm, a 2- a 3 = 4 μm.

Sternum (Fig. 4A ). Setae pubescent: b 1 and b 3 thick, with blunt apex. Seta b 2 slender, pointed, tapering. Lengths of setae: b 1 = 70 μm, b 2 = 33 μm, b 3 = 22 μm. Distance b 1- b 1 = 48 μm, b 2- b 2 = 78 μm, b 1- b 2 = 30 μm, b 3- b 3 = 36 μm. Seta b 1 1.5 times as long as interdistance, b 2 1.1 times as long as distance b 1- b 2, b 3 0.6 times of interdistance. st leaf-shaped, glabrous, 18 μm in length, st - st = 20 μm (Fig. 4B ). Posterior margin between b 1 straight. Two pubescent, triangular appendages present between b 1 and anal plate.

Anal plate (Fig. 4A ) 1.8 times as long as broad, slightly tapering posteriorly; lateral margins with one pair of thin, diverging, pubescent branches, 0.5 times of the length of plate; posterior 2/3 of plate divided into two tapering branches by a deep, V-shaped incision, each branch with two apical appendages: a submedian short, straight, tapering, glabrous one and a stalked bladder, sausage-shaped in sternal view. Bladder 0.7 times as long as plate. Plate glabrous, bladder densely granulated.

Etymology.

From the masculine Latin word " testudineus " meaning "with the pattern of tortoise shell" that refers to the testudinal pattern on the tergites of the new species.

Distribution.

China (Hunan). Known only from the type locality.

Remarks.

Samarangopus testudineus sp. nov. can be easily distinguished from all other congeners by the unique dorsal testudinal pattern on the body and the shape of protuberances on the body, as well as the anal plate. The dark-brown ridges composed of different structures and protuberances on tergites were only observed in S. amplissimus Scheller, 2009 from Indonesia, but their patterns are apparently different between the two species (vertically located on posterior part of tergites I-V in S. testudineus sp. nov. vs located on anterior part of tergite I and lateral part of tergites II-VI, curved). The species also differ in the shapes of marginal protuberances on tergite I (differentiated in three kinds, with pattern 1 tiny-3 large-41 small-3 large-1 tiny in S. testudineus sp. nov. vs with 38 similar leaf-shaped, large protuberances in S. amplissimus ), the shape of leaf-shaped protuberances (with reticulations in S. testudineus sp. nov. vs without reticulations in S. amplissimus ), the shape of globulus g on antenna (1.4 times as long as greatest diameter in S. testudineus sp. nov. vs 2.4 times as long as greatest diameter in S. amplissimus ), the shape of the setae on the pygidial sternum (cylindrical in S. testudineus sp. nov. vs slender and pointed in S. amplissimus ), and the anal plate (with sausage-shaped, granulated bladders in S. testudineus sp. nov. vs with ovoid, pubescent bladders in S. amplissimus ).

Figures

Figure 1. Samarangopus testudineus sp. nov. (holotype) A habitus, dorsal view, in alcohol B habitus, dorsal view, on slide. Scale bars: 100 μm.

Figure 2. Samarangopus testudineus sp. nov. (holotype) A tergites I-VI, showing the testudinal pattern B right antenna, tergal view (arrow indicates pin-shaped seta) C marginal leaf-shaped protuberance, sternal view D left posterior corner of tergite I, tergal view E left posterior corner of tergite IV, sternal view (arrow indicates tiny rod-shaped protuberance) F ridges on the tergite IV, lateral view on slide. Scale bars: 100 μm (A); 20 μm (B-F).

Figure 3. Samarangopus testudineus sp. nov. (holotype) A anterior margin of tergite I B left posterior corner of tergite I C hind margin of tergite I D ridges on tergite IV E left side of tergite II (black arrow indicates tiny rod-shaped protuberance, white arrow indicates round leaf-shaped) F marginal protuberances on tergite II, sternal view G tergite IV, left side (arrow indicates the same as in E). Scale bars: 20 μm.

Figure 4. Samarangopus testudineus sp. nov. (holotype) A sternum of pygidum and anal plate B tergum of pygidum C T 1 D T 3 E T 5 F tarsus of leg 1 G tarsus of leg 9 H setae on coxa and trochanter of leg 1 I setae on trochanter of leg 9. Scale bars: 20 μm.