Otostigmus (Parotostigmus) casus Chamberlin, 1914

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: 38-39

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Otostigmus (Parotostigmus) casus Chamberlin, 1914


Otostigmus (Parotostigmus) casus Chamberlin, 1914 

( Figures 5–10View FIGURES 5 – 6View FIGURES 7 – 10)

Otostigmus casus Chamberlin, 1914: 177  ;

Otostigmus (Parotostigmus) casus Attems, 1930: 164  ; Bücherl, 1940: 232; 1942: 63; 1974: 111.

Type material examined. Holotype MCZAbout MCZ IZ no.1481 (14278), Brazil, Mato Grosso, Madeira-Mamore, Railroad Camp 39, “Expedition: Stanford Expedition to Brazil 1911, Coll: W.M. Mann, 1911 ( Figs 5–6View FIGURES 5 – 6). 

Redescription. Length: 57 mm from the anterior margin of the cephalic plate to the posterior margin of tergite 21. Antennae with 17 articles, two basal articles glabrous. Cephalic plate smooth, without sutures and depressions, but with median sulcus anteriorly ( Fig. 7View FIGURES 7 – 10). Coxosternal tooth-plates, wider than long with 4+4 teeth and a strong seta on each plate. Coxosternite with a transverse suture at the base of the tooth-plates; this suture is laterally bifurcate (not described) ( Fig. 8View FIGURES 7 – 10). Margin of the forcipular trochanteroprefemoral process with one small medial denticle.

Tergites 1–6 smooth, from tergites 7–21 with tubercles, the number increasing gradually; the posterior tergites are densely tuberculate; tergites 12–20 more tuberculate laterally (keels and general surface scabrous). Tergites 5– 20 with complete paramedian sutures. Tergites 7–20 with a low median longitudinal keel (5 or 6); tergites 7–21 marginate (depressed from the fifth caudad, leaving the lateral margin distinctly elevated especially in the middle and caudal regions, but true margination only on tergite 21). Tergite 21 convex, its posterior margin with a shallow median longitudinal depression (last dorsal plate with the posterior edge moderately bowed out caudad and mesially truncate) ( Fig. 9View FIGURES 7 – 10).

Sternites 2–18 with a rounded depression in the center, those of sternites 2 and 3 very shallow;(with three pitlike depressions arranged in a triangle as usual; there are also three other depressions along the caudal border). Sternite 21 with posterior margin concave (narrowed caudad, the sides convex at the anterior ends, but straight and meeting in the middle at a slightly reentrant angle). Sternites without sutures. Coxopleuron without spines. Porefield covers almost all the coxopleuron, only its posterior end poreless ( Fig. 10View FIGURES 7 – 10).

Legs 1 with one tibial and two tarsal spurs in the tarsus; legs 2, 3, 6, 9, 17, and 18 with one tarsal spur (2 to 18 with a single tarsal spur). Ultimate legs missing (19 to 21 pairs of legs unknown).

Remarks. Chagas-Jr (2012) considered O. casus  as one of the most problematic Brazilian Otostigmus  to identify. His conclusion was preliminary, since he had not yet examined the type of O. casus  . Even so, he compared the original description of O. casus  with other Brazilian Otostigmus  and observed that O. casus  resembles O. tidius  in the presence of both short paramedian sutures on the sternites and two tarsal spurs at legs 1–8 ( Chagas-Jr 2012). After examining the type of O. casus  , I noticed that there are no short paramedian sutures on sternites, and two tarsal spurs at legs 1 only. Besides, both the dorsal integument and body size in O. casus  are more similar to the types of O. suitius  , O. rex  and O. samacus  than to O. tidius  . In O. casus  , O. rex  and O. suitius  the tergites have complete paramedian sutures from tergites 5–20, in O. samacus  from tergites 4–20. There is margination from tergites 7–21 in O. casus  and O. suitius  , and from tergites 6–21 in O. rex  and O. samacus  . The body length of O. casus  , O. rex  and O. suitius  varies from 55 to 78 mm, and in O. tidius  from 13 to 22 mm. The holotype of O. tidius  was not found in the myriapodogical collection of the Museum of Comparative Zoology, but Chagas-Jr (2012) examined ten specimens of O. tidius  from the states of Tocantins, Mato Grosso, Goiás, and Distrito Federal, Brazil  . As with in the case of O. casus  , O. rex  and O. suitius  , which were collected from the same locality in northwestern Mato Grosso state, have been described in the same work, and share characters in common, O. casus  is here considered as a junior synonym of O. suitius  . 


Museum of Comparative Zoology














Otostigmus (Parotostigmus) casus Chamberlin, 1914

Chagas-Jr, Amazonas 2016

Otostigmus (Parotostigmus) casus

Bucherl 1940: 232
Attems 1930: 164

Otostigmus casus

Chamberlin 1914: 177