Umbridesmus millequingentesimus (Attems, 1944) Vohland & Hamer, 2013

Vohland, Katrin & Hamer, Michelle, 2013, A review of the millipedes (Diplopoda) of Namibia, with identification keys and descriptions of two new genera and five new species, African Invertebrates 54 (1), pp. 251-251 : 268-269

Umbridesmus millequingentesimus (Attems, 1944) , comb. n.

Figs 31–36

Pagioprium millequingentesimum: Attems 1944: 239–241 , figs 26, 27.

‘ Pagioprium ’ millequingentesimum: Jeekel 1968: 104 ; Hamer 1998: 27.

Diagnosis: Very small polydesmids. Gonopod tibiotarsus extremely enlarged, ending in incised or undulate lamella ( Fig. 31).

Description:

Size: Width of male 0.9 mm, female 1.1 mm, length about 13 mm.

Head: Epicranial suture deep. Antenna long, antennomere 6>5>4=3=2>1>7; antennomeres 5+6 distally with microsensilla ( Fig. 32, ms).

Tergites and sternites: Metaterga slightly porous and wrinkled posterior to metatergal sulcus, which is smooth and often slightly curved. Paraterga narrow, broadly separated from metaterga. Prozonite with porous surface; suture between metazonite and prozonite smooth. Pleurotergal ridges ( Fig. 32, pt) distinct, in anterior body region dentate, best expressed in segments 6 and 7. Leg 2 with partly thickened podomeres ( Fig. 33). The distal 1–5 podomeres of the pregonopodal legs with brush ( Fig. 35). Sternite 5 with slightly indented subrectangular conus ( Fig. 34). Sternite distal to gonopods relatively broad, smooth. Hypoproct broadly rounded ( Fig. 36). Gonopodial aperture slightly protruding anteriorly.

Gonopods: Gonopod femur relatively broad, with large, sheath-like dentate process where the acropodite is bent at a right angle. Solenomere long, slender, acute and slightly curved around tibiotarsus, which consists of a subcircular plate and a short, tapering upward-directed process ( Fig. 31).

Holotype (examined): ♂ NAMIBIA: Outjo [20°06'32"S 16°09'17"E, 1267 m] (B 6437) ( NHMW).

Other material examined: NAMIBIA: 1♂ Helio , 19°03'S 16°29'E, 14.ii–23.iii.1987, E. Griffin, preservative pitfall traps ( SMN 21856 ) ( NMNW) .

Distribution: Namibia; Kaokoveld ( Fig. 1).

Remarks: The gonopod acropodite of the specimen from Helio is less bent and the slen- der tibiotarsus process is differently directed compared to the drawing of the holotype given by Attems (1944, figs 26, 27). As Attems tended to press the gonopods between slides and this is the only difference, we judge it as merely being a variation and not a different species.

Jeekel (1968) suggested an intrageneric relationship between ‘ Cnemodesmus ’ cavicolus Kraus, 1958, from Angola and ‘ Pagioprium ’ millequingentesimum from Namibia. Both species share the attribute of a sheath-like femoral process.

Order Spirostreptida Brandt, 1833

Family Spirostreptidae Brandt, 1833

Spirostreptid millipedes belong to the best-studied group of millipedes in southern Africa. Hamer (1999) provided detailed information about genera, and Dangerfield (1998) gave insights into their ecological role within semiarid ecosystems. Records are restricted to the more northern parts of Namibia ( Fig. 37).