Otostigmus (Parotostigmus) brunneus Chamberlin, 1921

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 : 37

Otostigmus (Parotostigmus) brunneus Chamberlin, 1921

( Figures 1–4 )

Otostigmus brunneus Chamberlin, 1921: 15 , Pl. 1, Fig. 4 ;

Otostigmus (Parotostigmus) brunneus Attems, 1930: 166 , Fig. 202; Bücherl, 1974: 109; Otostigmus (Androstigmus) brunneus Bücherl, 1940: 224 ; 1942: 60.

Type material examined. Holotype MCZ IZ no.2181 (31416), Guyana (British Guiana), 1st Mourie Expedition: Bryant Walker Expedition (Univ. of Michigan), 1914, F.M. Gaige, 5.viii.1914 ( Figs 1–2 ).

Redescription (male). Length: 34 mm from the anterior margin of the cephalic plate to the posterior margin of tergite 21. Left antenna with 20 articles and right with 21 (20 articles in both antennae); two basal articles glabrous. Cephalic plate smooth, without sutures or depressions (paired longitudinal furrows) ( Fig. 3 ).

Coxosternal tooth-plates equal in length and width with 4+4 teeth the two inner closer to each other than to the external ones, and with a strong seta in the middle of each plate. Coxosternite with a transverse suture at the base of the tooth-plates, and with a very short longitudinal suture. Margin of the forcipular trochanteroprefemoral process with two to three short denticles, and the tip pointed.

Tergites smooth; tergites 6–20 with complete paramedian sutures (from 4); tergites 4 and 5 with incomplete very short sutures in the anterior part; tergites 11–21 poorly-developed lateral (only 21st marginate); tergite 21 with posterior margin convex, not angled (strongly convex in middle).

Sternites with short incomplete paramedian sutures (not distinctly furrowed), but these sutures are not clearly visible because the specimen is contracted, and are therefore impossible to be seen in photographs. Sternites without depressions; sternite 21 shorter than sternite 20, with posterior margin straight (caudal margin incurved). Coxopleuron without spines and with pore-field that covers almost the entire coxopleuron, only the posterior end poreless.

Legs 1–3 with two tarsal spurs; legs 4–19 with one tarsal spur, and 20 and 21 without them. Prefemur of the right ultimate leg with a digitiform appendix three-fourths the length of the prefemur (reaching only two-thirds the distance to the caudal end of prefemur) ( Fig. 4 ); digitiform appendix has a tuft of hairs located in the center of the tip; the prefemur of the left ultimate leg without digitiform appendix.

Remarks. Chamberlin (1921) did not provide sufficient diagnostic characters to distinguish O. brunneus from other species of Otostigmus , including O. clavifer , which was described from the same type locality. Some characters of tergites such as surface and distribution of complete paramedian sutures are the same as described for O. brunneus and O. clavifer . The surface of the tergites in O. brunneus and O. clavifer is smooth, and the complete paramedian sutures are present from tergites 6 to 20. There are 4+4 coxosternal teeth and the transverse and short longitudinal suture under the tooth-plates are present and have the same configuration in O. brunneus and O. clavifer . However, the most peculiar character of O. brunneus is the digitiform appendix of the ultimate prefemur. This sexually dimorphic character is present only in males of many species of the subgenus Parotostigmus. The digitiform appendix of the ultimate prefemur of O. brunneus is three-fourths the length of the prefemur, and at its tip there is a central tuft of hairs. This appendix is quite similar to the appendix of O. clavifer in shape and position of the hair tuft (see redescription of O. clavifer ). Therefore, O. brunneus is hereby considered as a junior synonym of O. clavifer .

Figures

FIGURES 1 – 2. Otostigmus (P.) brunneus. Holotype MCZ IZ no. 2181 (31416), male. 1. Habitus, (dorsal view). 2. Habitus, (ventral view). Scale bars 5 mm.

FIGURES 3 – 4. Otostigmus (P.) brunneus. Holotype MCZ IZ no. 2181 (31416), male. 3. Cephalic plate and tergites 1 – 4. 4. Tergites of antepenult, penultimate and ultimate leg-bearing segments and prefemora of ultimate legs. DA-Digitiform appendix. Scale bars 1 mm.