Decapauropus biconjugarus Qian & Bu

Qian, Chang-Yuan, Bu, Yun, Dong, Yan & Luan, Yun-Xia, 2018, Study on the Pauropoda from Tibet, China. Part I. The genera Decapauropus and Hemipauropus (Myriapoda), ZooKeys 754, pp. 33-46 : 35

Decapauropus biconjugarus Qian & Bu sp. n. Figs 1, 2

Material examined.

Holotype, adult with 9 pairs of legs, female (slide no. XZ-PA2015025) (SNHM), China, Tibet, Motuo county, Dexing town, extracted from soil samples in a broad-leaved forest, alt. 1100 m, 29°40'N, 95°26'E, 3-XI-2015, coll. Y. Bu & G. Yang. Paratypes, 2 adults, with 9 pairs of legs, females (slides no. XZ-PA2015019 (SNHM), XZ-PA2015026 (SEM)), 2 subadults, with 8 pairs of legs (slides no. XZ-PA2015027 (SNHM), XZ-PA2015031 (SEM)), same data as holotype.

Etymology.

From the Latin biconjugarus referring to the anal plate with two pairs of clavate appendages.

Diagnosis.

Decapauropus biconjugarus sp. n. is distinguished from the other species in the genus by the shape of the anal plate: subquadrate, with obvious U-shape and concave lateral margins; distal part with 4 posteriorly directed clavate appendages, dorsal ones thickest, straight, annulate, those protruding from sternal side shorter and thinner, straight, glabrous. Posterior part of the pygidial sternum evenly rounded.

Description.

Holotype length 0.6 mm (Fig. 2A).

Head (Figs 1B, 2E). Dorsal head setae short to moderately long, clavate, lateral ones cylindrical. Relative lengths of setae, 1st row: a1 = 10, a2 = 8 (10); 2nd row: a1 = (9) 10, a2 = 18 (19) a3 = 14; 3rd row: a1 = 8 (10), a2 = (10) 12; 4th row: a1 = 8, a2 = (16) 18, a3 = (18) 20, a4 = (30) 32; lateral group setae l1 =26 (27), l2 = 22 (25) l3 = 20 (30); the ratio a1/a1-a1 in 1st row 0.8, 2nd row 0.4, 3rd row 0.4 and 4th row 0.4. Temporal organs oval in dorsal view, their length 1.4 times as long as their shortest distance apart. Head cuticle glabrous.

Antennae (Figs 1A, 2B, 2C). Antennal segment 4 with four cylindrical setae; relative lengths of setae: p = 100, p’ = (39.9) 41.4, p’’ = 62.5 (63.8), r = (26) 27.6; tergal seta p (1.2) 1.3 times as long as tergal branch t. The latter cylindrical, 2.2 (2.3) times as long as its greatest diameter and (1.6) 1.7 times as long as sternal branch s, which itself is 2.3 times as long as its greatest diameter. Seta q cylindrical, blunt, 1.3 times as long as s. F3 very thin with small base segment. Relative lengths of flagella (base segments included) and base segments: F1 = 100, bs1 = 6; F2 = 44.4, bs2 = 4; F3 =83.3, bs3 = 5. F1 4.5 times as long as t, F2 and F3 2.7 and 5.0 times as long as s respectively. Distal calyces small; F1 and F2 with fusiform flagella axes just below calyx. Distal calyces spherical; distal part of flagella axes fusiform. Globulus g 1.75 times as long as wide; about 12 bracts, capsule subspherical; width of g 0.67 of the greatest diameter of t. Antennae nearly glabrous.

Trunk. Setae on collum subcylindrical, striate, and appearing simple. Sublateral setae length 27 μm, 2.5 times as long as submedian setae (Figs 1C, 2D); sternite process triangular, pointed; appendages narrowing distally and with flat caps (Figs 1C, 2D). Setae on tergites thin, cylindrical; 4 + 4 setae on tergite I (Fig. 2 G), 6 + 6 on II–IV, 6 + 4 on V, 4 + 2 on VI. Tergites glabrous.

Bothriotricha . Relative lengths: T1 = 100, T2 = 126.7, T3 = 106.7, T4 =128.0, T5 = 206.7. Axes simple, straight, in all but T3 very thin; axes of T3 thickened in distal half (Figs 1D, 2F). Pubescent hairs simple, short, thin, strongest on distal half of T3.

Legs. Setae on coxa and trochanter of leg IX length 20 and 23 μm respectively, furcate with subcylindrical, annulate, blunt branches (Fig. 1E). Tarsus of leg IX long, 45 μm, tapering, 4.1 times as long as its greatest diameter (Fig. 1F). Proximal seta long, 14 μm, tapering, striate; distal seta 11 μm, tapering, striate; their lengths 0.35 and 0.30 of the tarsal length, respectively. Cuticle of tarsus glabrous.

Pygidum. Tergum (Figs 1G, 2H). Posterior margin evenly rounded but with small median triangular lobe between a1 and st, the lobe granulated distally. Relative lengths of setae: a1 = 100, a2 = 82.4, a3 = 117.6, st = 58.8. All setae subcylindrical, blunt, striate; st convergent; Distance a1-a1 0.64 of length of a1; distance a1-a2 3.3 times as long as a2-a3; distance st–st 1.5 times as long as st and 1.4 times as long as distance a1-a1. Sternum (Figs 1H, 2I). Posterior margin evenly rounded and smooth between b1. Relative lengths of setae (a1 =100): b1 = 235.3, b2 = 82.4. All setae subcylindrical, blunt, striate. Distance b1-b1 0.7 of length of b1; distance b1-b2 1.1 times as long as b2.

Anal plate subquadrate, with obvious U shape concave lateral margins; distal part with four posteriorly directed clavate appendages, tergal ones thickest, straight, annulate, those protruding from sternal side shorter and thinner, straight, glabrous. Tergal and sternal appendages 0.9 and 0.5 times as long as plate respectively. Plate and sternum glabrous.

Remarks.

This new species seems to be a very close relative of D. bedosae Scheller from north-western Thailand ( Scheller 1995) and D. cibodasensis Scheller from Singapore ( Scheller 2007). They can be distinguished by the shape of the posterior part of the pygidial sternum (margin evenly rounded in the new species vs. straight in D. cibodasensis ; with broad indentation in D. bedosae ) and by the shape of the anal plate (plate short with medium appendages in D. biconjugarus ; plate short with long appendages in D. cibodasensis ; plate longer with sort appendages, especially the sternal ones in D. bedosae ).