Towards improved taxonomic standards in Orthoptera: Critical examination of Cadena-Castañeda et al. (2025b) and proposed synonymies

Zootaxa recently published a monograph entitled “Studies on pygmy grasshoppers: On the current Metrodorinae sensu lato classification (Orthoptera, Tetrigidae) with emphasis on American and Malagasy taxa” by Cadena-Castañeda et al. (2025b). This monograph represents the most expansive revision of Tetrigidae taxonomy in recent history, spanning nearly 300 pages. Across South America and Madagascar, the authors describe two new subfamilies, seven new tribes, 12 new genera and 11 new species in their revision of the subfamily Metrodorinae. The revision of this subfamily is much needed and the monograph in question provides valuable data in the form of type specimen photographs. However, in this paper, we present numerous concerns regarding this revision, including factual errors, omissions of key information, questionable taxonomic decisions and inconsistently applied diagnostic characters. Most of the newly-described taxa lack any diagnostic information and their compositions, coupled with the provided data, do not allow for differentiation between taxa, prompting us to propose numerous taxonomic acts: Platytettix Hancock, 1906 syn . of Metrodora Bolívar, 1887; Tylotettix Morse, 1900 syn . of Metrodora ; Hebardidora Cadena-Castañeda & Tavares, 2025, syn. nov . of Metrodora ; Bolivaridora Cadena-Castañeda & Tavares, 2025, syn. nov . of Metrodora ; Morseidora Cadena-Castañeda & Tavares, 2025, syn. nov . of Armasius Perez-Gelabert & Yong, 2014; Armasius acutus comb. nov . of Metrodora acuta Günther, 1939; Metrodora mollilobata Kasalo & Skejo, 2025, stat. resurr .; Devrieseium Cadena-Castañeda & Tavares, 2025, syn. nov . of Chiriquia Morse, 1900; Stalitettix Cadena-Castañeda & Tavares, 2025, syn. nov . of Chiriquia ; Garciaitettigini Cadena-Castañeda & Tavares, 2025, syn. nov . of Metrodorini Bolívar, 1887; Otumbini Cadena-Castañeda & Tavares, 2025, syn. nov . of Metrodorini; Tumbrinckitettix Cadena-Castañeda & Tavares, 2025, syn. nov . of Cryptotettix Hancock, 1900; Holocerus devriesei Skejo, Medak, Pavlović, Kitonić, Miko & Franjević, 2020, comb. rev .