Explosive radiation versus old relicts: The complex history of Ethiopian Trechina, with description of a new genus and a new subgenus (Coleoptera, Carabidae, Trechini) Author Faille, Arnaud https://orcid.org/0000-0003-3274-5915 Department of Entomology, Stuttgart State Museum of Natural History, Stuttgart, Germany arnaud.faille@smns-bw.de Author Hofmann, Sylvia Leibniz Institute for the Analysis of Biodiversity Change, Museum Koenig, 53113 Bonn, Germany Author Merene, Yeshitla https://orcid.org/0000-0003-2998-822X Faculty of Biology, Philipps University Marburg, Marburg, Germany & Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia & Amhara Agricultural Research Institute, Bahir Dar, Ethiopia Author Hauth, David Faculty of Biology, Philipps University Marburg, Marburg, Germany Author Opgenoorth, Lars Faculty of Biology, Philipps University Marburg, Marburg, Germany Author Woldehawariat, Yitbarek https://orcid.org/0000-0002-0918-8906 Department of Zoological Sciences, Addis Ababa University, Addis Ababa, Ethiopia Author Schmidt, Joachim General and Systematic Zoology, University of Rostock, Rostock, Germany agonumschmidt@hotmail.com text Deutsche Entomologische Zeitschrift 2023 2023-09-27 70 2 311 335 http://dx.doi.org/10.3897/dez.70.107425 journal article http://dx.doi.org/10.3897/dez.70.107425 1860-1324-2-311 8D3E277C424C440B8FE878085239C2A2 65D0B2390EBE553382C9727ECC9CBF8F Subgenus Minitrechus Vigna Taglianti & Magrini, 2010 Type species. T. gypaeti Vigna Taglianti & Magrini, 2010. New synonymy. Archeotrechus Magrini, Queinnec & Vigna Taglianti, 2012 (type species: T. relictus Magrini, Queinnec & Vigna Taglianti, 2012), syn. nov. Remarks. Based on the molecular data, all Trechus species known to occur in the mountains of southern Ethiopia (Bale and Arsi Mountains, Gughe Highlands), form a monophyletic clade (Fig. 3 ). This clade includes species characterized by widely differing body sizes, shapes, and proportions, and by many other morphological characters, including elytral chaetotaxy, the number of dilated male protarsomeres, and the extent of the dorsal opening of the aedeagal median lobe. Similar character states can likewise be found in Trechus sensu lato species occurring in northern Ethiopia which, however, do not cluster within the south Ethiopian clade. At the current state of knowledge, a morphological definition of this clade together with a differential diagnosis with respect to other species groups of Trechus sensu lato cannot be presented here and require more comprehensive morphological investigations. For the monophyletic southern Ethiopian Trechus clade, the oldest valid species group name is Minitrechus Vigna Taglianti & Magrini, which was given for a very tiny, depigmented species from Mt. Enkuolo ( Vigna Taglianti and Magrini 2010 ). The subgenus Trechus Archeotrechus Magrini, Queinnec & Vigna Taglianti was described two years later for a likewise tiny and depigmented species from the Bale Mountains, which is additionally characterized by a very wide dorsal opening of aedeagus ( Magrini et al. 2012 ). In our phylogeny, the type species of both of these subgenera cluster together within one of the two main clades of South Ethiopian Trechus , both of which are highly supported by the molecular data (Fig. 3 ). Consequently, the status of Archeotrechus as a separate subgenus within Trechus sensu lato can no longer be maintained. A complete list of species we propose to summarize within the subgenus Trechus Minitrechus , is shown in the checklist of the Ethiopian Trechini species, see Discussion, below.