Aquatic beetle diversity from Volcan Tacana, Mexico: altitudinal distribution pattern and biogeographical affinity of the fauna Author Luna-Luna, Alba Magali Doctorado en Ciencias Biologicas y de la Salud, Universidad Autonoma Metropolitana, Mexico City, Mexico Author Martins, Caleb Califre https://orcid.org/0000-0001-5630-9865 Postdoctoral fellow, Instituto de Biologia, Departamento de Zoologia, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico Author Lopez-Perez, Andres Postdoctoral fellow, Instituto de Biologia, Departamento de Zoologia, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico Author Ramirez-Ponce, Andres https://orcid.org/0000-0003-4742-7397 Laboratorio de Ecosistemas Costeros, Departamento de Hidrobiologia, Universidad Autonoma Metropolitana-Iztapalapa, Mexico City, Mexico Author Contreras-Ramos, Atilano https://orcid.org/0000-0001-8044-1348 Red de Biodiversidad y Sistematica, Instituto de Ecologia, A. C., Xalapa, Veracruz, Mexico acontreras@ib.unam.mx text ZooKeys 2022 2022-07-11 1111 301 338 http://dx.doi.org/10.3897/zookeys.1111.68665 journal article http://dx.doi.org/10.3897/zookeys.1111.68665 1313-2970-1111-301 8EDF5CD7B0104B6DB90F0A6A1200C768 B17D24BEF89E503B813D064FB1E7AA5C Clarkhydrus sp. Comments. This species was collected at levels 4 (rivers 1 and 2, 1,448-1,619 m) and 5 (river 1, 1,763 m) on substrates of macrophytes and leaf packs, and was present throughout sampling months (February 2018 through February 2019, dry and rainy season). Specimens did not match known described species of the genus; however, they are close to C. decemsignatus , yet male genital morphology differs.