On the validity of Stegoloxodon Kretzoi, 1950 (Mammalia: Proboscidea)

Abstract

The binomen Stegoloxodon indonesicus was proposed by Kretzoi (1950) for a dwarfed elephantoid from Java, Indonesia. Based on a single molar from Ci Pangglosoran near Bumiayu initially referred to Elephas planifrons by van der Maarel (1932), Stegoloxodon indonesicus was considered a synonym of Elephas celebensis (Hooijer, 1949) by Maglio (1973). Van den Bergh et al. (1992) accepted a close relationship between these two taxa but argued in support of their separate specific status. Notably, in this and later works (e.g. van den Bergh 1999; van den Bergh et al. 1996, 2001) the generic name used for the two species was “Elephas” between quotation marks, an approach initially adopted for “E.” celebensis by Sondaar (1984, p.229), who noted that the “so-called “Elephas” celebensis from Sulawesi is most probably not Elephas at all”. The uncertain generic position of “E.” celebensis (and “E.” indonesicus) was further emphasized by van den Bergh (1999), who provided a revised diagnosis for “Elephas” celebensis, argued against Maglio’s (1973) hypothesis of paedomorphosis as the reason for primitive characters in this species, and suggested relationship to Primelephas or “one of the Stegotetrabelodontinae”, not entirely rejecting E. planifrons as a possible ancestor however. Van den Bergh’s analysis of “Elephas” celebensis is crucial for the understanding of the affinities of both this taxon and the closely related dwarf from Java but does not take a taxonomical step logically following from the author’s arguments.