Leposternon polystegum forms one of the eleven species of the genus Leposternon, which has
been shown to possess high morphological variability in some valid species, as well as contain
possible new taxa. The diagnoses and characterizations of most species were based on external
morphology, but not all species have well-defined diagnostic characters or an analysis of
morphological variation. Consequently, in the current study, specimens of L. polystegum from
scientific collections were analyzed to provide such morphological data, and so aid in the
diagnosis of the species and further the understanding of its geographic distribution.
Additionally, measurements from L. polystegum were compared with phylogenetically related
congeners with pre-cloacal pores. Eleven meristic and 39 morphometric characters were
analyzed, using descriptive and multivariate statistical analyses. The results of the current study
were structured into two chapters. In the first, L. polystegum is characterized morphologically
with new meristic and morphometric data, a diagnosis provided and the intraspecific variation
tested and identified as a possible clinal variation. Additionally, the geographic distribution of
L. polystegum was analysed and structured in a gazetteer and an updated map. In the second
article, L. mineiro, a species with pre-cloacal pores, was re-characterized with new
morphological data and its geographic distribution was expanded.
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