Over the course of their long research history, a plethora of scientific names have been applied to the different species of apes (Hominoidea). Although numerous authors, past and present, have attempted to reconstruct hominoid nomenclatural history in detail, it appears that parts of it, mostly concerning the lesser apes or gibbons, still remain overlooked. Here I show that Simia Nanodes Lichtenstein, 1791 is a senior synonym of Simia Moloch Audebert, 1797, otherwise regarded as the oldest binomen applicable to the Javan gibbon. However, since Simia Nanodes failed to enter common usage, these names are subject to a reversal of precedence as defined by Article 23.9 of the International Code of Zoological Nomenclature. Simia Moloch Audebert, 1797 must be maintained as a nomen protectum, resulting in Hylobates moloch (Audebert, 1797) staying the valid name of the species. Simia Nanodes Lichtenstein, 1791 is declared a nomen oblitum. In compliance with this, I provide a complete scientific synonymy of the Javan gibbon and comment on its early research history.
Keywords: History of primatology; Hylobates moloch; Nomen oblitum; Nomenclature; Reversal of precedence; Synonymy.