Otostigmus (Parotostigmus) scabricauda ( Humbert & Saussure, 1870 )

Chagas-Jr, Amazonas, 2016, A systematic appraisal of the types of ten species of Otostigmus (Parotostigmus) (Scolopendromorpha, Scolopendridae, Otostigminae), Zootaxa 4147 (1), pp. 36-58 : 49-50

Otostigmus (Parotostigmus) scabricauda ( Humbert & Saussure, 1870)

( Figures 26–33 )

Branchiostoma scabricaudus Humbert & Saussure, 1870: 203 ; Saussure & Humbert, 1872: 121, Pl. 6, Fig. 15 ; Otostigmus appendiculatus Porat, 1876: 23 (Synonymised by Attems, 1930); Branchiotrema scabricauda Kohlrausch, 1881: 75 ;

Otostigma brasiliense Meinert, 1886: 119 (Synonymised by Attems, 1930); Otostigmus scabricaudus Kraepelin, 1903: 123 , Fig. 61;

Otostigmus (Parotostigmus) scabricauda Attems, 1930: 159 , fig. 191; Bücherl, 1974: 117; Otostigmus (Androstigmus) scabricauda Bücherl, 1940: 221 ; 1942: 58.

Type material examined. Holotype NHMW 1015 , Rio de Janeiro, 1864, Tosh leg.

Diagnosis. Tergites 13–21 with scattered tubercles; tergites 5–20 more densely tuberculate laterally. Sternites 2–20 with a rounded anterior medial depression; sternites 4–13 with two small longitudinal rounded depressions in the middle; sternites 2–15 with three small transversal rounded depressions at the posterior margin. Legs 2–16 with one tarsal spur. Prefemur of ultimate legs of males with a digitiform appendix slightly shorter than the prefemur, and slightly flattened dorsoventrally; digitiform appendix with a tuft of hairs at the tip.

Redescription (male). Length: 70 mm from the anterior margin of the cephalic plate to the posterior margin of tergite 21. Antennae with 17 articles, the two basal articles glabrous. Cephalic plate smooth, without sutures and depressions, wider than long ( Fig. 26 ). Coxosternal tooth-plates wider than long; with 4+4 teeth, the two inner teeth closer to each other than to the external teeth; with a strong seta in the middle of each tooth-plate ( Fig. 28 ). Coxosternite with transverse and short longitudinal sutures at the base of the tooth-plates; the transverse suture is bifurcate laterally ( Figs 27 and 28 ). Forcipular trochanteroprefemoral process larger than tooth-plates, the margin with one medial denticle ( Fig. 28 ).

Tergite 1 overlying the posterior margin of the cephalic plate; tergites 1–4 without sutures; tergites 5–20 with complete paramedian sutures; tergites 5–21 marginate; tergites 1–12 smooth; tergites 13–21 with scattered tubercles; the number of tubercles on the tergites gradually increases from tergites 13–21; tergites 5–20 with gradually increasing lateral longitudinal rugosity; tergite 21 longer than wide, the posterior margin slightly convex; with slight longitudinal depression ( Fig. 29 ).

Sternites smooth, longer than wide; sternites 2–20 with a rounded anterior medial depression; sternites 4–13 with two small longitudinal rounded depressions in the middle; sternites 2–15 with three small transversal rounded depressions at the posterior margin; sternite 21 shorter than the preceding sternite, converging posteriorly; posterior margin of sternite 21 slightly concave and with a weak longitudinal depression ( Fig. 30 ).

Coxopleuron without spines, slightly prolonged posteriorly; pore-field covers almost all coxopleuron, only the posteromedian and posterolateral end poreless ( Fig. 30 ).

Legs 1 with one femoral, one tibial and two tarsal spurs; with two accessory pretarsal spines, and legs 2–16 with one tarsal spur. Prefemur of ultimate legs with a digitiform appendix slightly shorter than the prefemur ( Fig. 31 ); with a tuft of hairs at the tip ( Fig. 32 ) and slightly flattened dorsoventrally ( Fig. 33 ).

Remarks. O. scabricauda was briefly described by Humbert and Saussure (1870) in the genus Branchiostoma Newport, 1845 . Eleven years later, Kohlrausch (1881) transferred it to the genus Branchiotrema Kohlrausch, 1878 . Kraepelin (1903) redescribed O. scabricauda in detail and returned it to Otostigmus . Kraepelin’s redescription is very similar to this description of the type of O. scabricauda , so I think that he described the same specimen. O. scabricauda is widely distributed in Brazil, and was also recorded from Colombia, Ecuador and Peru ( Bucherl 1974). Chagas-Jr et al. (2014) excluded the Colombian record because of misidentifications and lack of the species in the examined collections. O. scabricauda is one of the several species of Parotostigmus in which the males have a digitiform appendix on the prefemur of the ultimate legs. As it was one of the first known species with this sexually dimorphic character, all other Otostigmus subsequently described with this feature were compared to it. However, as showed by Chagas-Jr (2012), the digitiform appendix is not exclusive to Brazilian Otostigmus , being also present in the males of other Neotropical and West African species; and at least among Brazilian Otostigmus , the morphology of the digitiform appendix is species-specific (for more details see Chagas-Jr 2012). The digitiform appendix of the holotype of O. scabricauda is almost the same length as the prefemur, slightly flattened dorsoventrally, and with a tuft of hairs right at the tip. Its tip is rounded. In studied specimens of O. scabricauda from Rio de Janeiro, the type locality, the digitiform appendix is similar to the holotype in shape and length, but the tuft of hairs emerges from a terminal concavity. The morphology of this appendix and its function need further investigation.

Figures

FIGURES 26 – 28. Otostigmus (P.) scabricauda. Type NHMW 1015, male. 26. Cephalic plate. 27. Forcipular segment and sternite 1. 28. Forcipular coxosternal tooth-plates and trochanteroprefemoral process. Scale bars 1 mm.

FIGURES 29 – 33. Otostigmus (P.) scabricauda. Type NHMW 1015, male. 29. Tergite of ultimate leg-bearing segment. 30. Sternite and coxopleuron of ultimate leg-bearing segment. 31. Right ultimate leg. 32. Prefemur of right ultimate leg showing the digitiform appendix. 33. Prefemur of right ultimate leg showing the digitiform appendix. DA—Digitiform appendix; TH— Tuft of hairs. Scale bars 1 mm.

FIGURES 15 – 17. Otostigmus (P.) cooperi. Holotype NMNH 2061590, female. 15. Habitus, (dorsal view). 16. Habitus, (ventral view). 17. Tergites 9 and 10 showing the keels. MLK—Median longitudinal keel. Scale bars 10 mm, except fig. 17 scale bar 1 mm.