Otostigmus rex Chamberlin, 1914

Chagas-Júnior, Amazonas, 2012, The centipede genus Otostigmus Porat in Brazil: Description of three new species from the Atlantic Forest; a summary and an identification key to the Brazilian species of this genus (Chilopoda, Scolopendromorpha, Scolopendridae, Otostigminae), Zootaxa 3280, pp. 1-28 : 23

Otostigmus rex Chamberlin, 1914

Type locality. Madeira-Mamoré R. R. camp 39, state of Mato Grosso.

Brazilian published records. None.

New records. Tocantins. Without specific locality, 02.i.1959, Hoge & Pedro ( IBSP 898). Distrito Federal. Brasília, área alfa da marinha, xi.1999 ( MNRJ 15043), ( MNRJ 15042) collected in x.1999 by G. Montingelli and ( MNRJ 15040) collected in ix.1999 by G. Montingelli, P. Valdujo and C. Nogueira.

Remarks. After the description of O. rex, Verhoeff (1937) and Bücherl (1939c, 1941, 1943) interpreted its holotype as a female of O. scabricauda . Chamberlin (1914) himself considered that O. rex was very similar to the female of O. scabricauda , but it differed by the abruptly and conspicuously different color of the cephalic plate and first tergite from the rest of the body. In addition, the less scabrous integument, its larger body size, the distribution of hairs on the third basal article of the antennae and the partially fused medial teeth of tooth plates were regarded as characters distinguishing it from O. scabricauda . I examined 14 specimens from Brasília, central Brazil, which I could assign to O. rex , including males that were recorded for the first time. Both male and female of O. rex agreed in almost all features, but the males presented a digitiform appendix different from that of the male of O. scabricauda . The appendix of the male of O. rex is shorter than the prefemur, more distally clavate and the tuft of hairs is located on the dorsal surface of the tip of this appendix. In O. scabricauda the digitiform appendix is equal to or longer than the prefemur, it is not distally clavate and the tuft of hairs is located right at the tip of the appendix. The digitiform appendix of O. rex resembles the digitiform appendix of the Andean species O. silvestrii , O. insignis , O. lavanus , O. parvior and O. mesethus , but O. rex does not have a prolongation of the coxa of legs 19 and 20.