Ctenus sigma ( Schenkel, 1953 )

Polotow, Daniele & Brescovit, Antonio D., 2012, Redescription of five Amazonian species of Ctenus Walckenaer (Araneae, Ctenidae, Cteninae), Zootaxa 3338, pp. 49-59 : 56-58

Ctenus sigma ( Schenkel, 1953)

Figs 6 A–B

Isoctenus sigma Schenkel, 1953: 35 , figs 31a–b ( male holotype from El Pozon , 10° 58'N, 68° 43'W, Departamento Acosta, Falcon, Venezuela, XI–XII.1924, Wiedenmeyer col., deposited in MHMB, examined ); Polotow & Brescovit 2009a: 590. Ctenus sigma: Polotow & Brescovit 2009a: 590 .

Diagnosis. Males of Ctenus sigma ( Figs 6 A–B) resemble those of Ctenus amphora ( Höfer et al. 1994: figs 1a–b) by the shape of the embolus and the long retrolateral tibial apophysis, but can be distinguished by the absence of an additional ventral projection on the retrolateral tibial apophysis and by the presence of a ventrally pointed tegular projection.

Description. Male (holotype). Colouration: carapace reddish brown, pars thoracica pale brown, thoracic groove dark brown; black rings around eyes; legs reddish brown, with ventral faces of coxae and femora lighter; chelicerae reddish brown; endites and labium reddish brown, lighter at tips; sternum reddish brown with lighter borders; abdomen gray, with dorsal anterior light area and two dark gray spots in dorsal median area; ventral abdomen yellowish with sparse dark dots. Total length 12.40. Carapace 6.60 long and 5.20 wide. Clypeus 0.20 high. Eye diameters: AME 0.35, ALE 0.25, PME 0.42, PLE 0.43. Chelicerae with 3 promarginal teeth, median larger; 4 retromarginal teeth, basal small; with intermarginal denticles. Leg measurements: I: femur 6.60/ patella 2.70/ tibia 6.40/ metatarsus 6.70/ tarsus 2.10/ total 24.50; II: 6.60/ 2.70/ 6.30/ 6.60/ 1.80/ 24.00; III: 6.10/ 2.50/ 5.40/ 6.20/ 1.70/ 21.90; IV: 7.50/ 2.70/ 7.30/ 9.30/ 2.60/ 29.40. Leg formula 4123. Leg spination: tibia I and II v2-2 -2-2-2, r0, p0, III and IV v2-2 -2, r1-1-0, p1-1-0; metatarsus I, II v2-2 -2, r0, p0, III v2-2 -2, r1-1-1, p1-1-1; metatarsus unmodified. Palp: tibia shorter than cymbium; retrolateral tibial apophysis slightly sub-apical; retrolateral tibial apophysis nearly as long as cymbium, laminar retro-prolaterally; cymbium without basal projections; tegulum with ventral and basal projection; embolus broad at base, with short tip and with laminar basal projection, indented at tip; median apophysis cup-shaped, bimarginate, short; conductor hyaline, C-shaped in retrolateral view ( Figs 6 A–B).

Female. Unknown.

Other material examined. None.

Distribution. Known only from the type locality, north of Venezuela ( Fig. 7 ).

Figures

FIGURE 6. Ctenus sigma (holotype). Male genitalia. A. Male palp, ventral view; B. Male palp, retrolateral view. Scale bar: 2.00 mm. Abbreviations: C, conductor; CY, cymbium; E, embolus; LBP, laminar basal projection of the embolus; MA, median apophysis; RTA, retrolateral tibial apophysis; TE, tegulum; TI, tibia.

FIGURE 7. Collection localities of five Ctenus species. A. South America; B. Close up, northeastern South America. Legend: square = C. delesserti; black circle = C. falconensis and C. sigma; gray circle = C. nigritus; triangle = C. serratipes.