A review of the previously monotypic tribe Dibolostethini (Chelodesmidae: Chelodesminae) with description of two new species and a summary of the Chelodesmidae of the Tropical Andes Biodiversity Hotspot Author Means, Jackson C. DFD2FDCA-264D-4CB2-99E7-8C2826EC9370 Virginia Museum of Natural History, 21 Starling Ave., Martinsville, Virginia 24112, USA. jackson.means@vmnh.virginia.gov Author Bouzan, Rodrigo S. 14A15A7F-730F-4D41-BDAC-D53514FAB85D Pós-graduação em Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil. & Laboratório Especial de Coleções Zoológicas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503 - 090, São Paulo, Brazil. rodrigobouzan@ib.usp.br Author Iniesta, Luiz Felipe Moretti DEEF048E-97FB-4CCD-875F-5FA6184CA8AB Laboratório Especial de Coleções Zoológicas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503 - 090, São Paulo, Brazil. luiz-moretti@hotmail.com Author Martínez-Torres, Daniela 3D6A9085-FE64-4647-9A4E-EC1599DD26D4 Grupo de Investigación en Aracnología & Miriapodología (GAM-UN), National University of Colombia, Bogotá, Colombia. sdmartinezt@unal.edu.co Author Vasquez-Valverde, Luisa F. F02C95CA-727E-4170-B81C-A25C9944E700 Department of Entomology, Virginia Tech, 216 A Price Hall, Blacksburg, VA 24061, USA. luisafvv@vt.edu Author Brescovit, Antonio D. 29156EF8-63CA-4499-8CB7-C57C20A9109B Laboratório Especial de Coleções Zoológicas, Instituto Butantan, Avenida Vital Brasil, 1500, 05503 - 090, São Paulo, Brazil. antonio.brescovit@butantan.gov.br Author Ivanov, Kaloyan AD3C06A4-8ECF-40AD-9D17-DCFC8818A5AC Virginia Museum of Natural History, 21 Starling Ave., Martinsville, Virginia 24112, USA. kal.ivanov@vmnh.virginia.gov text European Journal of Taxonomy 2023 2023-07-27 885 1 65 85 http://dx.doi.org/10.5852/ejt.2023.885.2189 journal article 59554 10.5852/ejt.2023.885.2189 f8509ab7-b884-41aa-a5ee-f8c425a46031 2118-9773 8205500 444CE1D2-8098-4CDE-9B97-927CA13FC39F Dibolostethus sicarius Hoffman, 2009 Figs 3A, E , 4A–B , 5 , 8–9 Dibolostethus sicarius Hoffman, 2009: 151 , figs 1–11. Diagnosis Adult males of D . sicarius differ from those of D. kattani sp. nov. based on the lack of short, blunt projections on the sternite of the 5 th body ring, and from D. inopinatus sp. nov. and D. kattani sp. nov. based on the following combination of gonopodal characteristics: solenomere relatively straight until gently curving dorsally at apex, tip sinuous ( Fig. 5A ); prefemoral process slightly wider basally, expanded at midpoint and recurved, forming a cup-shaped depression before apex; apex with three lamellate flanges, best seen in anterior view ( Fig. 5B ). Type material Holotype ECUADOR • ♂ ; Los Rios Province [originally reported incorrectly as Pichinchi Province], Rio Palenque Science Center ; [ 0.588° N , 79.362° W ]; 21 Mar. 1977 ; J. Reiskind leg.; VMNH110810 . Paratypes ECUADOR • 2 ♀♀ ; same collection data as for holotype; VMNH110811 , VMNH110812 . Fig. 3. Dibolostethus Hoffman, 2009 somatic characters continued. A, E . Dibolostethus sicarius Hoffman, 2009 , holotype, ♂ (VMNH110810). B–D . D. kattani Means, Bouzan, Martínez-Torres & Ivanov sp. nov. , holotype, ♂ (ICN-MD-1317-1). A . Coxa 2, mesal view, red arrow = gonopore. B . Left leg 4, posterior view, red arrow = tibial ventro-apical projection. C . Left leg of 5 th leg pair showing incrassate femur, red arrow = tibial ventro-apical projection. D . Body ring 5, lateral view, red circle = anterior pair of sternal projections. E . Prefemur 5, red arrow = basal pore. Abbreviations: Cx = coxa; Pf = prefemur. Description Male ( holotype , VMNH110810) With characteristics typical for the genus. Coloration (preserved in 70% isopropanol): body rings light brown to caramel; antennae and head light yellow; legs light yellow; telson reddish, with posterior margin (= spinnerets region) yellowish. Head: epicranial macrosetae 2+2, interantennal macrosetae 1+1, frontal macrosetae 2+2. Sternites: 4 th body ring with two thin, blade-like acute projections, tips separated throughout, nearly translucent ( Fig. 4A–B ). Gonopod aperture on 7 th body ring oval, rim notably projecting above sternite ( 0.35 mm ), with a deep U-shaped concavity ( 0.2 mm ) on posterior margin. GONOPODS ( Fig. 5 ). Gonocoxae rounded, equivalent to about three quarters the length of the telopodite; dorsum of left and right gonocoxa with 2 and 3 (possible aberration) macrosetae, respectively. Solenomere long, slender, unbranched, apex falciform and partially enveloped by prefemoral process ( Fig. 5 , S). Prefemoral process: long (similar in length to solenomere), width subequal to solenomere, widening at halfway point with a medial knob before curving laterad into a cup-like structure; apex broad, with a series of lamellate flanges resembling a hammerhead shark in lateral view ( Fig. 5 , PfP). BODY MEASUREMENTS (mm). Total length 24.8, width of 10 th body segment 1.98. Antennomere lengths (1–7): 0.38, 0.75, 0.85, 0.85, 0.85, 0.85, 0.25. Collum: length 0.5, width 1.4. Podomere lengths of 10 th body ring (1–7): 0.28, 0.55, 0.9, 0.34, 0.53, 0.95, 0.09. Gonopod aperture: length 0.50, width 0.78. Gonopod: length 0.99, width 0.86. Gonocoxae: length 0.63, width 0.36. Telopodite: length 0.98, width 0.31. Telson length 0.78. Fig. 4. Body ring 4, sternal projections. A–B . Dibolostethus sicarius Hoffman, 2009 , holotype, ♂ (VMNH110810). C–D . D. inopinatus Means, Bouzan & Ivanov sp. nov. , holotype, ♂ (VMNH110813). A, C . Lateral views. B, D . Posterolateral views. Abbreviation: Cx = coxae. Fig. 5. Dibolostethus sicarius Hoffman, 2009 , holotype, ♂ (VMNH110810), left gonopod. A . Lateral view. B . Anterior view. C . Mesal view. Red circles = cingulum. Dashed lines = prostatic groove. Abbreviations: PfP = prefemoral process; S = solenomere. Female ( paratype , VMNH110811) Coloration (preserved in 70% isopropanol) as in male. Body larger and more robust than male. Similar to male in general body outline and somatic characters, except sternite of 4 th body ring without pair of acute projections, 4 th , 5 th , and 6 th podosterna elevated to a lesser degree, 4 th and 5 th pair of legs not modified, and tibia lacking acute ventro-apical projections. BODY MEASUREMENTS (mm). Total length 30.95, width of 10 th body segment 2.6. Antennomere lengths (1–7): 0.38, 0.9, 0.93, 0.88, 0.85, 0.83, 0.23. Collum: length 1.0, width 1.7. Podomere lengths of 10 th body ring (1–7): 0.3, 0.53, 0.9, 0.38, 0.45, 0.98, 0.09. Vulvar aperture width 0.56. Posterior margin of vulvar rim: well sclerotized, U-shaped; width 0.13. Vulvae: small, unmodified, setose ( Fig. 8 ); length 0.45, width 0.29. Valves symmetrical. External valve: lateral length 0.5, lateral height 0.44; dorsal length 0.39, dorsal width at midpoint 0.14. Operculum: length 0.06, width 0.21. Telson length 1.15. Distribution Herein restricted to the Los Rios Province , Ecuador ( Fig. 9 ).