Decapauropus premnos, Scheller, Ulf, 2011

Scheller, Ulf, 2011, New records of Pauropoda (Myriapoda) from north-western Thailand, International Journal of Myriapodology 4, pp. 51-77 : 59-61

Decapauropus premnos sp. n. Figs 28-35

Material.

Holotype ad. 9(♀), Thailand, Chiang Mai province, Doi Inthanon, below the top, primary rain forest, soil, alt. 2400 m, 1991.vii.4, loc. CM-195. - Paratype subad. 8(♀), below the top, primary rain forest, soil, alt. 2400 m, 1991.vii.8, loc. CM-243. - Other material, 1 juv. 5, ibidem, Mae Chaem road, secondary dry forest, litter, alt. 1150 m, 1991.vi.30, CM-064. - 3 specimens.

Etymology.

From the Greek premnos, stump of a tree (referring to the thick stalk of the antennal globulus g).

Diagnosis.

Decapauropus premnos seems to be close to Decapauropus mortensenii (Hansen) which was described (1902) from the island Koh Chang in the Gulf of Thailand and later has been reported from Egypt, Seychelles, Sri Lanka, Java and Sumatra, and New Caledonia (with uncertainty also from Réunion, Mauritius and Australia). The new species can be distinguished from Decapauropus mortensenii by its thick stalk of the antennal globulus g, narrow in Decapauropus mortensenii ,the distal part of the bothriotrix T3, with marked swelling, not evenly thickened, by the shape of the tarsi, subcylindrical and only somewhat tapering, not slender and strongly tapering, by the proportion b2/b1-b2, as long as, not b2>b1-b2, and by the shape of the anal plate, longish and with evenly convex lateral margins, not shorter/broader and with shallow lateral indentation.

Description.

Length. 0.62 mm. Head (Fig. 28). Setae on the tergal side thin cylindrical annulate. Relative lengths of setae, 1st row: a1=a2=10; 2nd row: a1=?, a2=12, a3=14; 3rd row: a1=11, a2=10; 4th row: a1=8, a2=10, a3=?, a4=11; lateral group setae, l1=25, l2=26, l 3=?. Ratio a1/a1-a1 in 1st row 1.0, 2nd row?, 3rd row 0.6, 4th row 0.8. Temporal organs large, in tergal view ovoid, length 0.8 of shortest interdistance. Head cuticle glabrous.

Antennae (Fig. 29). Segment 4 with at least three cylindrical annulate setae; their relative lengths: p=10, p’ =6, r=5. Tergal seta p 1.2 times as long as the length of tergal branch t. The latter fusiform with distal end cut obliquely, 2.1 times as long as its greatest diameter and 0.9 of the length of sternal branchs,that branch twice longer than its greatest diameter; anterodistal corner distinctly truncate. Seta q cylindrical striate, 0.6 of the length of s. Relative lengths of flagella (basal segments included) and basal segments: F1=100, bs1=6; F2=27, bs2=4; F3=82, bs3=5. F1 5.0 times as long as t, F2 and F3 1.2 and 3.6 times as long as s respectively. Distal calyces somewhat flattened, distal part of flagella axes inconsiderably widened below calyces. Globulus g proportionally large, pyriform, with thick stalk, 1.2 times as long as wide, ≈12 thin bracts, capsule with flattened bottom; width of g 1.1 times as long as the greatest diameter of t. Antennae glabrous.

Trunk (Figs 30, 31). Setae of collum segment (Fig. 30) simple cylindrical striate, sublateral setae 1.4 times as long as submedian setae; sternite process triangular, blunt anteriorly; appendages barrel-shaped, caps low. Process and appendages glabrous. Setae on tergites as setae on the head, 4+4 setae on tergite I and 4+2 on VI, interposed tergites not studied. Submedian posterior setae on VI (Fig. 31) 0.3 of interdistance and 0.8 of the length of pygidial setae a1.

Bothriotricha (Fig. 32). Relative lengths: T1=100, T2=103, T3=76, T4=?, T5=107; axes simple straight, very thin and with faint pubescence only distally on T1, T2 and T5, T3 only (Fig. 32) stronger, with longish cylindrical end-swelling and distinct oblique pubescence.

Legs (Figs 33, 34). Setae on coxa (Fig. 33) and trochanter of leg 9 furcate, branches thin cylindrical striate, secondary branch somewhat thinner and shorter than primary one. These setae more anteriorly with rudimentary secondary branches. Tarsus of leg 9 (Fig. 34) subcylindrical, only somewhat tapering, 2.9 times as long as its greatest diameter; setae thin, proximal one tapering pointed, distal one subcylindrical blunt striate, proximal seta 0.4 of the length of tarsus and 2.1 times as long the length of distal seta. Cuticle of tarsus glabrous.

Pygidium (Fig. 35). Tergum. Posterior margin straight but with posterolateral corners rounded and two small rounded lobes just outside st. Relative lengths of setae: a1=st=10, a2=16, a3=26. Setae curved inwards, st also converging, a1 and st cylindrical with small swelling distally, a2 and a3 long thin tapering, a2 pointed. Distance a1-a1 0.7 of the length of a1, distance a1-a2 1.4 times as long as a2-a3; distance st-st 1.8 times as long as st and 1.1 times as long as distance a1-a1.

Sternum. Posterior margin with five rounded lobes, one on each side of insertion areas of setae b1 and one below base of anal plate. Relative lengths of setae (pygidial a1=10): b1=28, b2=19, setae thin tapering pointed glabrous, b1 1.1 times as long as interdistance, b2 1.1 times as long as distance b1-b2.

Anal plate large, directed posteriorly, 1.7 times longer than broad, lateral margins convex, narrowing off posteriorly and with U-shaped posterior incision, length of the latter 0.3 of the length of plate, plate glabrous.