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Background. The concept of name-bearing specimens is pivotal for nomenclatural stability. Hence, correctly listing the type specimens and designating lecto- and neotypes are crucial elements in taxonomic revisions. While reviewing the Labeo Cuvier, 1816 taxa of the Congo basin, we encountered several differences between the lists of type specimens provided in the various revisions of the genus. The majority of problems were encountered with six nominal species of Labeo that were described by Boulenger in 1898: Labeo barbatus Boulenger, 1898; Labeo falcifer Boulenger, 1898 (later replaced by Labeo falcipinnis Boulenger, 1903); Labeo lineatus Boulenger, 1898; Labeo longipinnis Boulenger, 1898; Labeo macrostoma Boulenger, 1898; and Labeo velifer Boulenger, 1898. For four of these species: L. barbatus, L. lineatus, L. macrostoma, and L. velifer, different specimens appear in the literature as name-bearing types. Also for Labeo lividus Roberts et Stewart, 1975, previously a junior synonym of L. barbatus, and for Labeo altivelis Peters, 1852, a species described from the lower Zambezi but also present in the Congo basin, alternative lists of type specimens were mentioned in the literature. Materials and methods. The correct list of type specimens was compiled based on museum archives and on an examination of the type specimens. The validity of the lectotype designations was checked. When a lectotype designation proved to be ambiguous, the actions of the subsequent revisers were investigated. Results. We found that the correct lectotypes of L. barbatus, L. falcipinnis, L. lineatus, L. longipinnis, L. macrostoma, and L. velifer are: BMNH 1898.12.28:7, MRAC 17, BMNH 1897.9.30:27, MRAC 113, MRAC 35, and BMNH 1898.12.28:1, respectively. Also for L. lividus and L. altivelis, confusion existed on the type series and a corrected list of type specimens is presented. Conclusion. Especially in older species descriptions, a detailed list of studied specimens is often lacking. In such cases, providing a correct list of type specimens is often not a trivial task. This study shows that inaccurate lists of type specimens can lead to invalid taxonomic acts, which could have nomenclatural implications. We hope that increased efforts in the dissemination of basic taxonomic information will reduce such errors in the future.
Maarten Van Steenberge (Thu,) studied this question.