Decapauropus extremus, Scheller, Ulf, 2014

Scheller, Ulf, 2014, New records of Pauropoda (Myriapoda) with descriptions of new taxa, Zootaxa 3866 (3), pp. 301-332 : 315-317

Decapauropus extremus n. sp.

Figs 11–19

Type specimen. Holotype: ad. 9 (♀), Mexico, Yucatan, ca. 100 km S from Merida, between Lol-Tun and Labna, ca. 20°12′N, 89°32′W; 50 m a. s. l, tropical forest, in leaf litter, September 11, 2002, W. Niedbała leg. Type specimen deposited in the Zoological Museum, University of Lund, Sweden.

Diagnosis. In most pauropods the seta q on the lower side of the sternal antennal branch s has its insertion point in the middle. In a few cases, however, in the genera Pauropus , Decapauropus, Propepauropus, Hemipauropus and Brachypauropus the insertion point is distinctly displaced into the anterior half of the branch but such an extremely distal position as in D. extremus n. sp. has not been observed before. Thereby and together with the circular shape of the anal plate and the unusually long a -setae of the pygidium the new species is well defined.

Derivation of name. From the Latin extremus = outermost, referring to the subdistal insertion of the seta q of the sternal antennal branch.

Description. Length: 0.96 mm.

Head (Fig. 11). Tergal setae long thin blunt, striate densely. Relative lengths of setae, 1st row: a 1 = a 2 = 10; 2nd row: a 1 = a 3 = 12, a 2 = 13; 3rd row: a 1 = 11, a 2 = 13; 4th row: a 1 = 11, a 2 = 26, a 3 = 17, a 4 = 13, lateral group setae thin pointed, l 1 = 22, l 2 = 21, l 3 = 20. Ratio a 1 /a 1– a 1 in 1st row 1.5, 2nd 0.9, 3rd 1.6 and 4th row 1.3. Temporal organs in tergal view longish, length 0.5 of shortest interdistance. Head cuticle glabrous.

Antennae (Fig. 12). Segment 4 with 5 thin cylindrical striate setae, r thinnest, their relative lengths: p = 10, p' = 5, p'' rudimentary, r = 6. Tergal seta p 0.7 of the length of tergal branch t. The latter 5.1 times as long as its greatest diameter and 1.3 times as long as sternal branch s, that branch 2.6 times as long as its greatest diameter; anterodistal corner of s distinctly truncate, particularly inside flagella F 2. Seta q as p and p´ of 4th segment, 0.7 of the length of s, insertion point just below the base of F2. Relative lengths of flagella (basal segments included) and basal segments: F 1 = 100, bs 1 = 8; F 2 = 49, bs 2 = 5; F 3 = 80, bs 3 = 5. The F 1 2.1 times as long as t, F 2 and F 3 1.6 and 3.1 times as long as s respectively. Distal calyces very small, conical, distal part of flagella axes not widened below calyces. Globulus g almost cylindrical, 1.1 times as wide as long, ≈10 bracts, capsule with flattened bottom, width of g as long as greatest width of t. Antennae glabrous.

Trunk (Figs 13–14). Setae of collum segment (Figure 13) similar, furcate, main branch cylindrical, blunt, annulated, striate, secondary branch cylindrical too and shorter but not studied in detail, sternite process small, narrow anteriorly, appendages with flattened caps, process and appendages pubescent. Setae on anterior tergites similar to submedian setae of head and lengthening posteriorly, on posterior tergites long pointed; 4+4 setae on tergite I, 6+6 on II-V, 4+2 on VI. Submedian posterior setae on tergite VI (Figure 14) long, thin, pointed, somewhat curved inwards, length 1.1 times as long as interdistance and 1.3 times as long as the length of pygidial setae a 1. Tergites glabrous.

Bothriotricha (Figs 15–16): relative lengths: T 1 = T 2 = 100, T 3 = 82, T 4 = 65, T 5 = 129; axes simple, T 1 (Fig. 15) and T 2 very thin, proximal halves glabrous, distal halves with long sparse, partly branched hairs; T 3 and T 5 thicker, the former (Fig. 16) with oblique simple pubescence hairs, the latter with very delicate pubescence.

Legs (Figs 17–18). Setae on coxa and trochanter (Fig. 17) of leg 9 furcate, branches cylindrical, blunt, striate, secondary branch somewhat shorter than primary branch. Tarsus of leg 9 (Fig. 18) distinctly tapering, 4.7 times as long as its greatest diameter; setae cylindrical, proximal seta long, tapering, very thin distally, glabrous, distal seta short, cylindrical, blunt, with short pubescence, proximal seta 0.6 of the length of tarsus and 5.8 times as long as distal seta. Cuticle of tarsus glabrous.

FIGURES 11–19. Decapauropus extremus n. sp., holotype ad. 9 (♀). 11. Head, right half. 12. Right antenna, sternal view. 13. Collum segment, median and left part, sternal view. 14. Tergite VI, median and right posterior corner. 15. T 1. 16. T 3. 17. Seta on trochanter of leg 9. 18. Tarsus of leg 9. 19. Pygidium, median and left part, sternal view. Scale: a: 11, 14, 13, 15; b: 12, 16–19.

Pygidium (Fig. 19): Tergum: Posterior margin evenly rounded. Relative lengths of setae: a 1 = 10, a 2 = 13, a 3 = 24 and 25; all setae directed posteriorly, a -setae long, thin, tapering, pointed glabrous, a 1 almost straight, a 2 and a 3 somewhat curved inwards, st cylindrical. blunt, with distinct but short pubescence. Distance a 1– a 1 0.6 of the length of a 1; distance a 1– a 2 1.4 times as long as distance a 2– a 3; distance st–st twice longer than st and 0.4 of the length of distance a 1– a 1. Cuticle glabrous.

Sternum: Posterior margin between b 1 indented shallowly and with low broad lobe below anal plate. Relative lengths of setae (pygidial a 1 = 10): b 1≈11, b 2 = 5; setae tapering pointed, striate weakly distally, b 2 curved inward and converging; b 1 about as long as interdistance, b 2 as long as distance b 1– b 2.

Anal plate circular, glabrous, two short setiform appendages protruding backwards from distal part of sternal side, these cylindrical blunt, length half of the length of the plate.