Podochresimus unistolonus Attems, 1944

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 : 263-265

Podochresimus unistolonus Attems, 1944

Figs 17–22

Podochresimus unistolonus: Attems 1944: 245–246 , figs 34–36; Jeekel 1968: 107; Hoffman 1968: 221.

Diagnosis (based on illustration in Attems (1944)): Gonopod with one long, curved and apically tapered femoral process ( Fig. 17, fp). Process at base of solenophorous tibiotarsus branch ( Fig. 17, b) long and spiniform, and third process of postfemoral region slightly ventrally directed, and apically widened ( Fig. 17, a).

Description (after Attems (1944)):

Size: Width: metazonites 1.25 mm, prozonites 1 mm.

Colour: Body and antennae dark castaneous brown, legs light yellow.

Tergites and sternites: Pleural keels weakly expressed, dorsally limited by a depression, posteriorly rounded, only on last segments forming small tooth. Metazonites dorsally smooth, with two transverse rows of minute, fragile bristles on first five segments. Metatergal sulcus well developed. Anterior segments with fine, ridged pleural keels. Sternites with deep, cross­like depression and four fields of fine bristles. Sternite 5 with large conus between anterior legs, either subdivided into two knobs or even and enlarged distally. Hypoproct broadly rounded, paraprocts with small lateral bulges.

Legs: Long. Femur of legs on segments 3–8 with large bulge terminally. Tibia and tarsus of anterior legs with dense brush.

Gonopods: Prefemur elongated. Femur medially broader than distally, and on medial side, having a distal, curved lateral branch ( Fig. 17, fp). Tibiotarsus with three branches, two of which are basally connected, and third which is solenophorous ( Fig. 17, c).

Remarks: No types were designated by Attems (1944), but Hoffman (1968) stated that the syntypes are in the NHMW. He did not provide any details concerning them. The gonopods of the type material ( Fig. 18) do not match those illustrated by Attems (1944) in his original description of the species ( Fig. 17). We can only assume that the incorrect gonopods were placed in the container for P. unistolonis , and the origin of these gonopods and the identity of the species to which they belong are unknown. It is therefore not possible to be certain about the source of the other body parts examined ( Figs 19–22), although these do seem to match the description by Attems (1944).

Syntype (examined): NAMIBIA: 1♂ “ Kapland , Camacis ” [19°07'30"S 13°36'54"E, 827 m] (Inv. NR. 3475; Attems B 6429; NHMW) .

Distribution: Known only from the type locality in Namibia. The original label is partly illegible and this has led to some confusion as to the correct type locality.Attems (1944) cited ‘Kapland: Besfontein, Camacis’ in South Africa as the type locality in the original species description. Lawrence (1962), however, suggested ‘Sesfontein’ and ‘Camaeis’ in the former Kaokoveld, Namibia, as the correct type locality, because these two localities were sampled during the South African Museum’s Expedition in 1925 and 1926. Considering that Lawrence’s (1962) assumption appears to be the most plausible, the type locality is here regarded as being within Namibia ( Fig. 1).

Genus Praeterpediculus Vohland , gen. n.

Etymology: From Latin praeter (alongside) and pediculus (small foot), in reference to its small size, with legs appearing comparatively long.

Type species: Phaeodesmus niger Attems, 1928 .

Diagnosis: Medium­sized paradoxosomatids with expressed pleural keels on first segments, frons setose, microsensilla on antennomere 6+7 ( Fig. 25), femoral processes (adenostyles) on leg pairs 3–5 ( Fig. 26) and indented sternital process on segment 5. Gonopod with short, stout, anteriad-directed femoral process at the base of solenophore ( Figs 23, 24, fp). Solenophorous tibiotarsus elongated ( Fig. 23, tt, 24, s).

Remarks: While we initially hesitated to erect a monotypic genus, work by Jeekel (1968) and Hoffman (1981) supports this decision. Praeterpediculus niger was originally described as a species of the genus Phaeodesmus by Attems (1928), but as Phaeodesmus is defined as having the gonopod tibia and bi­ or tri­ramous tarsus clearly separated, this concept does not fit the species, and as a result, P. niger was assigned to the genus Habrodesmus Cook, 1896 by Attems (1944).

The concept of Habrodesmus , tribe Xanthodesmini Jeekel, 1968 , has a colourful history. In a key to the species, Cook (1896: 97) defined the genus Habrodesmus , but only later did he formally describe the type species, H. laetus Cook, 1898 . Attems (1944) chose Habrodesmus andreinii Brölemann, 1904 , as the type, which was not valid ( Kraus 1956). This species is currently placed in Oranmorpha Verhoeff, 1941 ( Jeekel 1968) . Jeekel (1968) listed mainly west African species as belonging to Habrodesmus . He and subsequent taxonomists (Hoffman 1981) excluded P. niger from Habrodesmus because of the elongated tibiotarsus and solenomere of the gonopods.

Hoffman (1981) suggested Anaclastopus as a new genus for Phaeodesmus neglectus Attems, 1934 , and also discussed assigning P. niger to the new genus, as Jeekel (1968) had already indicated uncertainty about its placement by including quotation marks for ‘ Habrodesmus ’ niger and ‘ H.’ neglectus . In fact, there are similarities concerning the gonopods: in both genera, Anaclastopus and Praeterpediculus , the solenomere and tibiotarsus are elongated and parallel. However, there are some differences that force a generic distinction: the gonopods in A. neglectus are bent in comparison to P. niger , resulting in the small (post)femoral process being directed mesally in A. neglectus and anteriorly in P. niger . The solenomere and tibiotarus are longer and more strongly curved in A. neglectus , while in P. niger they are straight to slightly curved.

In terms of somatic characters, A. neglectus has only one femoral process (adenostyle) on leg pair 3; the constriction between metazonite and prozonite is smooth compared to the structure in P. niger ; the metatergal sulcus is only faintly visible compared to the structured one in P. niger ; the process on sternite 5 is flat compared to the indented one in P. niger ; and, lastly, there are small projections on sternite 6 and two subcoxal cones on the rear margin of sternite 8, none of these are features being seen in P. niger .

According to Hoffman’s (1981) discussion of the tribal position of Anaclastopus , Praeterpediculus is placed in the tribe Cnemodesmini instead of Xanthodesmini because of the (post)femoral process.