Revision of the Neotropical spider genus Acanthoctenus (Araneae: Ctenidae Acanthocteninae) Author Arizala, Stephany Instituto de Biologia, Universidade Estadual de Campinas, (PG-IB / UNICAMP), Bloco O CP- 6109. Av. Bertrand Russel s / n. CEP 13083 - 865 Campinas, SP, Brazil. Author Labarque, Facundo Martín 0000-0001-9413-1949 Departamento de Ecologia e Biologia Evolutiva (DEBE), Universidade Federal de São Carlos (UFSCar), Campus São Paulo. Rodovia Washington Luís, Km 235, CEP 13565 - 905 São Carlos, SP, Brazil. & facundo. labarque @ gmail. com; https: // orcid. org / 0000 - 0001 - 9413 - 1949 facundo.labarque@gmail.com Author Polotow, Daniele 0000-0002-1069-1808 Departamento de Ecologia e Biologia Evolutiva (DEBE), Universidade Federal de São Carlos (UFSCar), Campus São Paulo. Rodovia Washington Luís, Km 235, CEP 13565 - 905 São Carlos, SP, Brazil. & danielepolotow @ gmail. com; https: // orcid. org / 0000 - 0002 - 1069 - 1808 danielepolotow@gmail.com text Zootaxa 2021 2021-01-27 4920 1 1 55 journal article 8507 10.11646/zootaxa.4920.1.1 8cd8a768-c115-4b2e-8167-f9ae52eb4f80 1175-5326 4471454 89E38EAD-A8D2-4ED9-A7D0-8C388A785E61 Acanthoctenus plebejus Simon, 1906 Figs 10B , 26–28 Acanthoctenus plebejus Simon, 1906: 291 , fig. 2A (female lectotype from Trinidad , Trinidad and Tobago , [ 10°41’30.5”N , 61°13’21.0”W ], deposited in MNHN AR5169, here designated, examined).—Mello-Leit„o 1936: 201.— World Spider Catalog 2020 . Acanthoctenus spinipes — Simon 1893: 430 (misidentification).— World Spider Catalog 2020 . Note. In the original description, Simon (1906: 291) mentioned several localities for Acanthoctenus plebejus including: Caracas and San Esteban cities, and a locality close to the intersection between Orinoco and Caroni rivers ( Venezuela ), Trinidad Island ( Trinidad and Tobago ), and Tarapoto city ( Peru ) (“— Venezuela : Caracas ! San Esteban ! Orinoco : Caroni .—Trinidad.— Amazonas : Tarapoto !”). It seems that Simon studied a syntype series, however, he did not provide a list of examined material in the original description (1906: 291). Also , Simon described (1906: 291) and illustrated (1906: fig. 2a) one female, but it might not be the same specimen. As the MNNH holds only a female specimen of A. plebejus ( MNNH AR5169 ) from Trinidad , we consider it as part of the syntype series and here designate it as lectotype . Diagnosis. Females of Acanthoctenus plebejus ( Figs 26 , 27D , 28 ) resemble those of A. spinipes ( Figs 16 C–D, 17C, 18A–B) by the atrium massive, subquadrangular, and the copulatory ducts strongly sclerotized. It can be distinguished by the median sector wide anteriorly extending into the atrium, the atrium anterior border slightly sclerotized, and the lateral sectors anterior border strongly curved. A. spinipes lacks an extension of the median sector into the atrium, presents strongly sclerotized anterior and lateral borders of the atrium, and straight anterior borders in the lateral sectors. Description. Male. Unknown. FIGURE 26. Acanthoctenus plebejus Simon, 1906 , female holotype (MNHN AR5169). A, epigynum, ventral; B, internal genitalia, dorsal. FIGURE 27. Acanthoctenus plebejus Simon, 1906 , female holotype (MNHN AR5169). A–C, habitus; A, dorsal; B, ventral; C, frontal. D, epigynum, ventral. Female ( holotype MNHN AR5169). Total length 15.02. Carapace 6.29 long and 5.18 wide. Clypeus 0.32 high. Eye diameters: AME 0.27, ALE 0.17, PME 0.34, PLE 0.47. Leg measurements: I: femur 7.12/ patella 2.69/ tibia 8.38/ metatarsus 7.01/ tarsus 1.95/ total 27.15; II: 7.07/ 2.96/ 6.85/ 5.90/ 1.88/ 24.66; III: 5.47/ 2.29/ 4.70/ 5.72/ 1.94/ 20.12; IV: 6.78/ 2.24/ 6.29/ 6.29/ 2.01/ 23.61. Leg formula 1243. Leg spination: tibia I and II v2-2-2-2-2-2-2-2-2, p-1-1-0-1-1-1, r-0-1-1-1, III v-2-2-2, p-1-1, r-1-1, IV v-2-2-2, p-1-1-1, r-1-1-1-1; metatarsus I and II v-2-2-2-2-2-2, p-1-0-1-1, r-1-0-1, III and IV v-2-2-2, r-1-1-1, p-1-1-1. Epigynum ( Figs 26 , 27D , 28 ): median sector subpentagonal, as wide as long, wide anteriorly extending into the atrium, projected posteriorly; anterior border of the lateral sectors curved; atrium large, subquadrangular; copulatory ducts strongly sclerotized, curved, S-shaped; spermathecae head quote-shaped, with apical glandular openings, spermathecae base curled; fertilization ducts tubular, slanting outwards. Distribution. Known only from the type locality in Trinidad and Tobago ( Fig. 10B ).