Spirostreptus Brandt 1833

Mwabvu, Tarombera, Hamer, Michelle, Slotow, Robert & Barraclough, David, 2009, A revision of the taxonomy and distribution of Spirostreptus Brandt 1833 (Diplopoda, Spirostreptida, Spirostreptidae) with descriptions of a new species and a new genus of spirostreptid millipede, Zootaxa 2211, pp. 36-56 : 38-39

Genus Spirostreptus Brandt 1833

Spirostreptus Brandt 1833 , p. 203 (type species: Spirostreptus sebae Brandt 1833 ; by subsequent designation of Pocock, 1894, p. 388); Spirostreptus: Attems 1914, 1928 ; Hoffman 1965, 1979, 2008; Krabbe 1982; Golovatch & Hoffman 2000; Hamer 1998, 1999; Hoffman et al. 2001; Mwabvu 2005b, 2006

Triaenostreptus Attems 1914 , p. 149 (type species Spirostreptus triodus Attems 1909 , by subsequent designation of Jeekel, 1970, p. 139); Attems 1928; Golovatch & Hoffman 2001; Hoffman 1971, 1979, 2008; Krabbe 1982; Hamer 1998

Diagnosis: Large spirostreptid millipedes, body length 162–344 mm; antennae 9–13 mm; minimum and maximum body width 4–15 mm and 11–19 mm, respectively.

Prozonite 1–3 mm wide and metazonite 1–2 mm wide.

Number of body rings 60–73.

Three separate sclerites form the prebasilar plate of the gnathochilarium.

Collum with an anterior lobe, black or dark brown in colour, with 2–5 complete folds and 0–7 incomplete folds.

Body black or brown in colour. Legs, antennae and anal valve colour generally lighter shades of body colour, often light brown.

Prozonite yellowish to brown; metazonite with one row of sagilla. Ozopores begin on 5th or 6th body ring.

Gonopod 6–9 mm long; sternite triangular; paracoxite fused tightly to the metaplica, apically horizontal. Telocoxites approximately parallel to each other, medial edge straight and close together.

Proplica approximately 2/3 of gonopod length; proplica broad sub-apically, setose apically. Proplica with a central groove flanked by sharply raised lateral and medial edges.

Thumb-like lateral lobe present between the distal telocoxite lobe and apical proplica, lateral lobe directed towards paracoxite at an angle to lateral edge of distal lobe.

Distal telocoxite enlarged and laterally produced into rounded golf club-shaped lobe ( Figs 1 a, 2a, 3a, 4a, 5a, 6a).

Metaplica with a small window through which part of pre-knee telopodite is visible ( Figs 1 b, 2b, 3b, 4b, 5b, 6b).

Telopodite knee and origin of antetorsal process concealed under apex of proplica. Antetorsal process tapering; post knee telopodite coils or spirals proximally, becoming lamellate before narrowing distally into a long thin extension with a trifurcate ending. Antetorsal process straight, S-shaped or crescent-shaped, with terminal spine ( Fig. 7 ).

Distribution: Known from southern Africa ( Angola, Botswana, Democratic Republic of Congo, Mozambique, Namibia, South Africa, Zambia and Zimbabwe).

Remark: Although Hoffman (2008) did not use the presence of the distal lobe and the slanting digitiform lateral lobe to define Spirostreptus in his key to the genera of Spirostreptini, we think that these characters are taxonomically more informative at the genus level than the form of the antetorsal process.

The distribution of the genus shows large gaps even in habitats similar to those from which the genus is known. These gaps are mainly in less accessible regions which suggest that current understanding of the distribution is a result of collecting bias rather than a true fragmentation.

Figures

FIGURE 1. Spirostreptus heros (NMSA 20495). a, oral view of gonopods; b, aboral view of gonopods; c, oral view of prefemoral lobe of first pair of male legs; d, lateral view of collum. Abbreviations: p, proplica; m, metaplica; llb, lateral lobe; dl, distal lobe; d, depression; tp, telopodite; at, antetorsal process; pc, paracoxite; st, sternite; cf, collum fold; al, anterior lobe; pfl, prefemoral lobe.

FIGURE 7. Shape of antetorsal process of the telopodites of Spirostreptus species. a, S. heros; b, S. kruegeri; c, S. sebae; d, S. unciger; e, S. batokensis; f, S. tripartitus. Abbreviations: tp, telopodite; tk, telopodite knee; at, antetorsal process.