This paper specifically highlights a taxonomic issue we term nomen phantasma (ghost name), a case where a species' identity, initially based on a past description or illustration, is later given a different description that is inconsistent with the original. This new, divergent description then becomes the reference for biological entities resembling the new description, deviating from the true original. Our analysis of the case of Nandus nebulosus (1835) serves as a prime example of a nomen phantasma that urgently requires attention to address the shortcomings of nomen dubium, nomen nudum, and simple misidentification, which do not fully capture the specific nuances of historical deviation from primary visual evidence. The issue of nomen phantasma does not stop at tracing the original publication but often necessitates a historical investigation into the use of the name, the impact of which can affect conclusions in various branches of biology, such as conservation studies, biogeography, and evolution. This manuscript is officially published under the auspices of the Veritas Research Project – Hasiholan Science Explorer. www.hasiholan.org © 2026 Hasiholan Science Explorer. License: CC BY-NC-ND 4.0 International DOI: https://doi.org/10.5281/zenodo.19686859 Terms of Use: Proper attribution must be given to the original authors. Reproduction or distribution of this work for commercial purposes, as well as any modification or derivation of the original text, is strictly prohibited without prior written permission from the copyright holder. The integrity of this manuscript is protected under the HSE Ontological Veto protocol.