Ctenus nigritus F.O. Pickard-Cambridge, 1897

Polotow, Daniele & Brescovit, Antonio D., 2012, Redescription of five Amazonian species of Ctenus Walckenaer (Araneae, Ctenidae, Cteninae), Zootaxa 3338, pp. 49-59 : 52-54

Ctenus nigritus F.O. Pickard-Cambridge, 1897

Figs 3 A–D

Ctenus nigritus F. O. Pickard-Cambridge, 1897: 81 , pl. 3, figs 6 a, 7 a ( male holotype from Santarém, 2 ° 26 ˏ 34 ʺS, 54 ° 42 ˏ 28 ʺW, Pará, Brazil, 1896, E.E. Austen col., deposited in BMNH 1896.12. 13.98, examined ).

Diagnosis. Males of Ctenus nigritus resemble those of C. manauara ( Höfer et al. 1994: fig. 7 a–b) by the prominent ventral tegular projection, but can be distinguished by the larger RTA, which is truncated at the apex, and the shape of the retrolateral tibial apophysis ( Figs 3 A–B). Females resemble those of C. manauara ( Höfer et al. 1994: fig. 8 a) by the shape of the epigynal median sector, but can be distinguished by the visible ovoid projection and the apical position of the lateral sector processes ( Fig. 3 C).

Note. The holotype is faded; the colour description is based on the male and female deposited in MPEG 6939.

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; abdomen gray with several small black spots, with dorsal anterior light area and two gray dark spots in dorsal median area; ventral abdomen with V-shaped black area, from epigastric furrow to spinnerets, with two white spots near epigastric furrow. Total length 14.50. Carapace 8.00 long and 6.20 wide. Clypeus 0.32 high. Eye diameters: AME 0.40, ALE 0.25, PME 0.42, PLE 0.50. Chelicerae with 3 promarginal teeth, median larger; 4 retromarginal teeth, basal small; with intermarginal denticles. Leg measurements: I: femur 9.00/ patella 3.60 / tibia 8.80 / metatarsus 8.60 / tarsus 2.80 / total 32.80; II: 8.70 / 3.30 / 8.60 / 8.20 / 2.40 / 31.20; III: 7.40 / 3.00/ 6.30 / 7.40 / 2.00/ 26.10; IV: 9.60 / 3.20 / 8.20 / 12.00/ 2.90 / 35.90. Leg formula 4123. Leg spination: tibia I and II v 2 - 2 - 2 - 2 - 2, r 1 - 1 -0, p 1 - 1 - 1 -0, III and IV v 2 - 2 - 2, r 1 - 1 -0, p 1 - 1 -0; metatarsus I, II v 2 - 2 - 2, r 1 - 1 -0, p- 1 - 1 -0, III v 2 - 2 - 2, r 1 - 1 - 1, p 1 - 1 - 1; metatarsus IV unmodified. Palp: tibiae as long as cymbium; RTA on apical margin of tibia, short, broad and flattened, pointed ventrally; cymbium elongate, without basal projections; tegulum projected; embolus with large base, short tip and with laminar basal projection; median apophysis cup-shaped, bimarginate and short; conductor hyaline, C-shaped in retrolateral view ( Figs 3 A–B).

Female ( MPEG 6889). Colouration as in male. Total length 15.60. Carapace 6.80 long and 5.60 wide. Clypeus 0.22 high. Eye diameters: AME 0.28, ALE 0.17, PME 0.34, PLE 0.36. Chelicerae with 3 promarginal teeth, median larger; 4 retromarginal teeth, basal small; with intermarginal denticles. Leg measurements: I: femur 6.10 / patella 3.00/ tibia 5.70 / metatarsus 5.10 / tarsus 1.70 / total 21.60; II: 5.80 / 2.90 / 5.00/ 4.90 / 1.70 / 20.30; III: 5.20 / 2.60 / 3.90 / 4.70 / 1.60 / 18.00; IV: 6.40 / 2.50 / 5.60 / 8.10 / 2.10 / 24.70. Leg formula 4123. Leg spination: tibia I and II v 2 - 2 - 2 - 2 - 2, r0, p0, III and IV v 2 - 2 - 2, r 1 - 1, p 1 - 1; metatarsus I, II v 2 - 2 - 2, r0, p0, III v 2 - 2 - 2, r 1 - 1, p 1 - 1, IV v 1 - 1 - 1-2 - 2, r 1 - 1, p 1 - 1. Epigynum: median sector subrectangular, invaginated anteriorly; with two projecting ovoid lobes; lateral spurs originating medially in lateral sector ( Fig. 3 C); oval spermathecae; copulatory ducts, long, large and curved; fertilization duct short, originating from retrolateral side of spermathecae ( Fig. 3 D).

Variation. 10 males: total length 14.50–24.50; carapace 8.00– 13.70 long; femur I 9.00– 14.20. 10 females: total length 15.60–26.70; carapace 6.80–12.60 long; femur I 6.10–10.30.

Additional material examined. BRAZIL. Pará: Almeirim, Laranjal do Jari (00o 35 ' 27.94271 "S 52 o 44 ' 9.24822 "W), 3 females ( MPEG 6893 , 6908); 1 female ( MPEG 6926 ); (00o 41 ' 25.93745 "S 52 o 49 ' 9.21553 "W) 4 males and 5 females ( MPEG 6894 , 6895, 6914, 6927, 6932, 6939, 6951); (00o 41 ' 45.28868 "S 52 o 48 ' 32.29253 "W), 1 female ( MPEG 6935 ); 2 males ( MPEG 6899 , 6901); (00o 42 ' 33.18001 "S 52 o 46 ' 57.49371 "W), 11 females ( MPEG 6913 , 6915, 6920); 1 male and 11 females ( MPEG 6898 , 6902, 6906, 6936, 6945, 6949); (00o 42 ' 42.64747 "S 52 o 40 ' 0.86094 "W), 1 female ( MPEG 6943 ); (00o 42 ' 8.76351 "S 52 o 38 ' 8.94836 "W), 1 male and 3 females ( MPEG 6888 , 6942, 6954, 7595); (00o 49 ' 58.65601 "S 52 o 39 ' 29.69148 "W), 1 female ( MPEG 6934 ); (00o 53 ' 16.53963 "S 52 o 50 ' 41.59495 "W), 1 female ( MPEG 6950 ); (01o01' 32.45885 "S 52 o 54 ' 17.27678 "W), 2 females ( MPEG 6918 , 6937); 5 males and 4 females ( MPEG 6911 , 6925, 6931, 6938, 6953); (01o01' 33.12220 "S 52 o 34 ' 2.78573 "W), 2 males and 3 females ( MPEG 6886 , 6940, 6947); (01o 11 ' 28.30705 "S 52 o 38 ' 51.85530 "W), 2 males and 4 females ( MPEG 6892 , 6896, 6904, 6941, 6952); (01o 35 ' 13.05213 "S 52 o 39 ' 31.63974 "W), 2 females ( MPEG 6889 , 6897, 6929); (01o 36 ' 14.72106 "S 52 o 39 ' 9.44026 "W), 1 female ( MPEG 6916 ); Melgaço ( Estação Científica Ferreira Penna , FLONA Caxiuanã , 0 1 o 44 ' 15.5 " S 51 o 26 '42.0"W), 1 male and 1 female ( MPEG 9322 ); Juruti ( Ramal Pacoval , km 2, 0 2 o 28 ' 0.6 " S 56 o 12 ' 42.2 "W), 1 male ( MPEG 14930 ); ( Comunidade Café Torrado ), 3 males and 1 female ( MPEG 14004 , 14931, 14932).

Distribution. North of the State of Pará, Brazil ( Fig. 7 ).

Figures

FIGURE 3. Ctenus nigritus (male holotype and female MPEG 6889). Male genitalia. A. Male palp, ventral view; B. Male palp, retrolateral view. Scale bar: 1.00 mm. Female genitalia. C. Epigynum, ventral view; D. Vulva, dorsal view. Scale bar: 0.50 mm. Abbreviations: C, conductor; CD, copulatory duct; CY, cymbium; E, embolus; FD, fertilization duct; LBP, laminar basal projection of the embolus; LL, lateral lobes; LS, lateral sectors; MA, median apophysis; MS, median sector; OL, ovoid lobes; OP, ovoid projection; RTA, retrolateral tibial apophysis; S, spermathecae; 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.