Praeterpediculus niger (Attems, 1928) 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 : 265-268

Praeterpediculus niger (Attems, 1928) , comb. n.

Figs 23–30

Phaeodesmus niger: Attems 1928: 249 , figs 503–506, 567.

Habrodesmus niger semiflavus: Attems 1944: 243 .

‘ Habrodesmus ’ niger: Jeekel 1968: 111 ; Hamer 1998: 27.

‘ Habrodesmus ’ semiflavus Jeekel, 1968: 111; Hamer 1998: 26. Syn. n.

Diagnosis: Tibiotarsus and solenomere elongate, fused together from shortly after base, apically tibiotarsus forms a sheath that covers the longer, acute solenomere. Distinct, apically acute femoral process ( Figs 23, 34).

Description:

Size: Width 1.2 mm, length about 16 mm.

Colour: Dark brown; border of collum, tip of antenna and distal parts of antennomere 6+7, posterior to metatergal fold dirty white, lighter posterior to metatergal suture.

Head: Epicranial suture distinct, ending above antenna. Antennomeres 6+7 with microsensilla, in antennomere 7 less expressed than in antennomere 6 ( Fig. 25).

Collum: Widely rounded, anterior and lateral margin slightly raised.

Tergites and sternites: Metatergite in segment 2 set lower than collum ( Fig. 25), broadly bordered. Pleurotergal ridges slightly dentate in segments 2–4. In segment 3, metatergite with small border, protruding slightly backwards, pleurotergal ridges slightly broader than in 2 nd segment, in segment 4 smaller. From segment 5 onwards, paraterga protruding backwards, relatively narrow, only slightly acute. Anterior legs up to segment 8 with tarsal brush ( Fig. 29, tb); on 8 th segment in first leg pair more expressed than in second one; femur of 3 rd to 5 th pair of legs with a ventral digitiform projection (adenostyle) ( Fig. 26, fp). Suture between meta- and prozonite as well as metatergal sulcus costulate ( Fig. 28, msu, pmj). Sternital process on 5 th segment indented. Epiproct truncate to slightly indented, bent down in lateral view ( Figs 27, 30).

Gonopods: Femur medially broadened. Lateral femoral process small and acute, slightly variable in size and orientation. Tibiotarsus and solenomere separated at the base, then fused together, acute solenomere only free at tip ( Figs 23, 24).

Syntype of Habrodesmus niger (examined): 1♂ NAMIBIA: Namutoni [18°48'27"S 16°56'25"E, 1099 m] (B5939) ( NHMW) .

Syntype of H. (P.) niger semiflavus (examined): 1♂ NAMIBIA: Kaoko Otavi [18°18'04"S 13°39'10"E, 1422 m] (B6464) ( NHMW) .

Other material examined: NAMIBIA: 1♂ Kunene district, Wolfsnes , 19°03'S 15°52'E, 24.iii–10.v.1988, E. Griffin ( SMN 21909 ) ( NMNW) ; 1♂ same data but 12.ii–16.iii.1987 ( SMN 21848 ) ( NMNW) ; 1♂ Kunene district, road to Ondundu Mountains [19°32'S 15°27'E, 1271 m], 12.ii–17.iii.1987, E. Griffin ( SMN 21852 ) ( NMNW) ; 1♂ Kunene district [?], N of Kamaseb [co­ordinates uncertain], 13.ii–20.iii.1987, E. Griffin ( SMN 21854 ) ( NMNW) .

Distribution: Namibia. Widely distributed in northern part of the country ( Fig. 1).

Habitat: Most of the samples consist of many specimens. The animals may have been aggregating in favourable (humid) habitats in the same manner as described by Shelley and Crawford (1996) for C. riparius . It would be a challenging investigation to see how this aggregation behaviour might be related to the success of the species; one of the few millipedes living in this semi-desert country.

Remarks: The closest relative is probably Anaclastopus neglectus (Attems, 1934) from Katanga, Democratic Republic of Congo, which also has the solenomere and tibiotarsus parallel. Attems (1934 a) as well as Jeekel (1968) and Hoffman (1981) stressed the close relationship of these species.

Attems (1944) distinguished niger and niger semiflavus only because of differences in colouration. Consecutive taxonomic publications listed them as distinct species ( Jeekel 1968; Hamer 1998) without explaining their status as two valid species. Reinvestigation of the types could not solve the colour problem as the colour was leached out. There is some variation in the degree of curvature of the solenomere and tibiotarsus between the populations, but no consistent form in the type material examined which would allow any distinction indicative of different species. Other features such as the form of the conus in segment 5, the form of the pleural keels and the occurrence of the femoral process in the pregonopodial legs were stable.

The co­ordinates for Kamaseb in the Kunene district could not be identified since Kamaseb is, in fact, located much further south than the Kunene district.

The syntype material in the NHMW is labelled as being from the South African Museum in Cape Town .

Genus Umbridesmus Vohland , gen. n.

Etymology: From Greek umbra (shade) and desmus (millipede), in reference to the umbrella-shaped distal projection of the tibiotarsus.

Type species: Pagioprium millequingentesimum Attems, 1944 .

Diagnosis: Small paradoxosomatid species with distinct pleurotergal ridges ( Fig. 32, pt) and sternal cones ( Fig. 34). Gonopod tibiotarsus widely enlarged, with lamellate sheath, solenomere acute ( Fig. 31).

Remarks: Jeekel (1968) suggested a generic relationship between ‘ Cnemodesmus ’ cavicolus Kraus, 1958, from Angola and Pagioprium Attems, 1937 , due to similarities in the position and relative length of the tibiotarsus and the femoral processes. ‘ Cnemodesmus ’ cavicolus is much larger, however, and thus a revision of the type material is required. At this stage, the genus Umridesmus is monotypic. Jeekel (1951) synomised Pagioprium under Tectoporus Carl, 1902 , which is restricted to species from Java, Sumatra and Sulawesi (as Celebes) ( Jeekel 1968; Hoffman 1979; Hamer 1998).