Dasongius spatulatus, Bu, 2021

Bu, Yun, 2021, Two new species of the genus Dasongius (Myriapoda, Pauropoda, Pauropodidae) from China, Zootaxa 4908 (2), pp. 239-250 : 244-249

Dasongius spatulatus sp. n.

Figures 22‒37 , Table 1.

Material examined: Holotype, male adult with 9 pairs of legs (slide no. JS-WX-PA2018001), China, Jiangsu Province, Wuxi City, Daji Mountain , extracted from soil samples in bamboo forest, elev. 5 m, 31°32’10’’N, 120°12’43’’E, 8-X-2018, coll. Y. Bu. Paratypes, 1 male adult with 9 pairs of legs (slide no. JS-WX-PA2017035), same locality as holotype, 9-X-2017, coll. Y. Bu ; 2 male adults with 9 pairs of legs (slide no. SH-DSGY-PA2017001, SH-DSGY- PA2017002), China, Shanghai, Jing’an district, Jing’an sculpture park, samples in urban broad-leave forest, elev. 23 m, 31°14’30’’N, 121°27’55’’E, 5-VIII-2017, coll. Y. Bu & Y. L. Jin. Non-type material, 1 juvenile with 6 pairs of legs (slide no. SH-DSGY-PA2017003), same data as paratypes from Shanghai .

Diagnosis. Dasongius spatulatus sp. n. is characterized by the cylindrical, non-furcate setae on the collum segment; long seta p on tergal branch and long q on sternal branch of antenna; 6+6 setae on tergite II; furcate setae on coxa and non-furcate setae on trochanter of leg 9; tergum of pygidium with long and granulated seta a 1 and a 2, and spatulate seta st; anal plate glabrous, separated into two processes posteriorly, and with 2 short, granulated, lanceolate appendages. Dasongius spatulatus sp. n. is distinctly different from the D. rugosus and D. bicrurus by the shape of anal plate. It is similar to D. liupanensis sp. n. in the shape of the setae on the head, collum segment, tergites, and legs. They can be distinguished by the shape of the tergum of the pygidium, shape of anal plate, as well as the shape of seta a 1, a 2, st and b 1 of the pygidium ( Table 1). The differences of four known species of the genus are compared in Table 1.

Description. Adult body length 0.86 (0.78) mm (n = 4); white to pale yellow and pygidium light brown in alcohol ( Fig. 30 ).

Head ( Figs. 22 , 31 ). Dorsal head setae short to moderately long, annulate, clavate, lateral ones slender. Relative lengths of setae, 1 st row: a 1 = 10, a 2 = 10; 2 nd row: a 1 = 8, a 2 = 18, a 3 = 13 (11); 3 rd row: a 1 = 6 (5), a 2 = 9 (8); 4 th row: a 1 = 7, a 2 = 13 (12), a 3 =14, a 4 =13; lateral group setae l 1 =10 (11), l 2 = 13 (10) l 3 = 15(12); the ratio a 1 / a 1 – a 1 in 1 st row 1.3, 2 nd row 0.4 (0.5), 3 rd row 0.6, and 4 th row 1.4. Temporal organs oval in dorsal view, their length 0.8 (0.9) of their shortest distance apart. Head cuticle glabrous. Antennae ( Fig. 23 ). Chaetotaxy of segments 1–4: 2/2/3/4. Antennal segment 4 with four cylindrical, annulate setae; relative lengths of setae: p = 100, p ’ = 64 (60), p ’’ = 46, r = 61; tergal seta p 1.4 (1.7) times as long as tergal branch t. The latter subcylindrical, swollen distally, 3.3 (3.0) times as long as its greatest diameter and 1.2 (1.3) times as long as sternal branch s, which itself is 2.0 (1.8) times as long as its greatest diameter. Seta q cylindrical, annulate, 1.4 times as long as s. Relative lengths of flagella (base segments included) and base segments: F 1 = 100, bs 1 = 9 (10); F 2 = 38 (45), bs 2 = 6; F 3 = 76, bs 3 = 9 (10). F 1 3.9 (4.3) times as long as t, F 2 and F 3 1.9 (2.5) and 3.8 (4.3) times as long as s respectively. Distal calyces small, hemispherical; Flagella axes cylindrical below calyx. Globulus g 1.8 times as long as wide; with 10 bracts, capsule spherical; width of g 0.4 (0.5) of the greatest diameter of t. Antennae glabrous. Trunk. Setae on collum cylindrical, annulate. Sublateral setae length 20 (22) μm, 2.2 (2.4) times as long as submedian setae ( Fig. 24 ); sternite process triangular, pointed; appendages narrowing distally and with flat caps ( Fig. 24 ). Setae on tergites thin, cylindrical; 4 + 4 setae on tergite I ( Fig. 32 ), 6 + 6 on II–IV ( Figs. 33, 34 ), 6 + 4 on V ( Fig. 35 ), 4 + 2 on VI; shortest seta 7 μm and longest one 38 μm on I–V; posterior setae on VI moderate, 40 (30) μm, their mutual distance 22 (16) μm. Tergites I–V glabrous, VI with dense pubescence on posterior part. Bothriotricha. Relative lengths: T 1 = 100, T 2 = 113, T 3 = 119, T 4 = 134, T 5 = 194 (175). T 1 – T 4 with simple, straight axes and dense pubescence ( Figs. 33–35 ). T 5 with thicker axis; pubescence sparse and long in proximal part, dense and short in distal part, same as in D. liupanensis sp. n. ( Figs. 9 , 37 ). Genital papillae ( Fig. 26 ). Base segments cylindrical. Length of papillae = 20 (18) μm, greatest diameter =13 (12) μm, length of seta= 11(11) μm. Proximal part of genital papillae subcylindrical, distal part conical, seta 0.6 (0.5) of length of papilla. Cuticle glabrous. Coxal seta of leg 2 same as on leg 1. Legs. Setae on coxa and trochanter of legs 1–8 subcylindrical, short, and annulate. Setae on coxa of leg 9 furcate with subcylindrical, annulate, blunt branches, length 12 (13) μm, on trochanter of leg 9 cylindrical, slender, annulate, length 13(14) μm ( Fig. 36 ). Tarsus of leg 1–8 each with only 1 distal, annulate seta, 5 (6) μm ( Fig. 25 ). Cuticle of tarsus pubescent. Tarsus of leg 9 tapering, 40 μm, 4.0 (4.4) times as long as its greatest diameter ( Fig. 27 ). Proximal seta 20 (15) μm, tapering, striate; distal seta 10 (8) μm, cylindrical, annulate; their lengths 0.5 (0.4) and 0.2 (0.3) of the tarsal length, respectively. Pygidium. Tergum ( Figs. 28 , 37 ). Surface highly modified as engraved, honeycombed, pentagonal and tetragonal cellae. Pygidium about as long as wide. Anterior margin straight, posterior margin with one deep indention in the middle. Lengths of setae: a 1 = 33 (30) μm, a 2 = 43 (40) μm, a 3 = 50 (45) μm, st = 9 μm. All setae tapering, pointed, a 1 and a 2 granulated distally, a3 pubescent; st spatulate, with apical 1/3 part broadened; Distance a 1 – a 1 0.5 (0.4) of length of a 1; distance a 1 – a 2 2.0 times as long as a 2 – a 3; distance st–st 1.3 (1.2) times as long as st and 0.8 (0.9) of distance a 1 – a 1. Sternum ( Fig. 29 ) pubescent, posterior margin with distinct indentation between between b 1. Lengths of setae: b 1 = 35 (30) μm, b 2 = 38 (30). Both seta b 1 and b 2 tapering and pubescent. Distance b 1 – b 1 0.9 of length of b 1; distance b 1 – b 2 0.5 of length of b 2. Anal plate ( Fig. 29 ) glabrous, 2.8 (2.9) times as long as broad, posterior half of plate divided into 2 tapering processes, each of them with 1 short, granulated and lanceolate appendages inserted basally and protruding backwards, 0.7 of length of plate.

Etymology. The species name “ spatulatus ” refers to the spatulate seta st on tergum of pygidium.

Distribution. China (Jiangsu, Shanghai).

Figures

FIGURES 22–27. Dasongius spatulatus sp. n. 22, head, right part, dorsal view; 23, right antenna, tergal view; 24, collum segment, median and right part, sternal view; 25, tarsus of leg 1; 26, right male genital papillae; 27, tarsus of leg 9. Scale bars: 20 μm.

FIGURES 28–29. Dasongius spatulatus sp. n. 28, tergum of pygidium; 29, sternum of pygidium. Scale bars: 20 μm.

FIGURES 30–37. Dasongius spatulatus sp. n. 30, habitus; 31, head, dorsal view; 32, tergite I; 33, tergite II; 34, tergite IV; 35, tergite V; 36, coxa and trochanter of leg 9; 37, tergite VI and tergum of pygidium. Scale bars: 100 μm (30); 20 μm (31–37).

FIGURES 7–9. Dasongius liupanensis sp. n. 7, tergum of pygidium; 8, T 3; 9, T. Scale bars: 20 μm.