期刊名称：Publicación Electrónica de la Asociación Paleontológica Argentina
电子版ISSN：2469-0228
出版年度：2021
卷号：21
期号：2
DOI：10.5710/PEAPA.24.07.2021.388
语种：English
出版社：Asociación Paleontológica Argentina
摘要：The early Miocene marine deposits in Tierra del Fuego bear a group of struthiolariid gastropods that stand out for their high morphological variability. since the end of the 19th century this variability was interpreted as reflecting (1) a highly diversified rapidly evolving group of species or (2) a single, plastic species characterized by ample intraspecific variability. The morphological study of more than 100 specimens of the Fuegian struthiolariid genus Perissodonta Martens collected in the Carmen Silva, Viamonte, and Irigoyen formations indicate that significant parameters, such as shell shape, spire length and number of spiral and axial sculptures (cords, threads, tubercles) vary continuously within an ample range of values, favoring a single, plastic species. Topotype specimens of Perissodonta ameghinoi (Ihering), collected from the early Miocene Monte León Formation in Patagonia, show similar plasticity of characters. Furthermore, recent topotype material of Perissodonta georgiana Strebel from Islas Georgias del Sur, a species considered very close or junior synonym of the genotype species P. mirabilis (Smith), indicates a similar degree of plasticity. Accordingly, the Fuegian struthiolariids previously assigned to Perissodonta ameghinoi; P. fueguina (Ihering); or P. densestriata (Ihering) are here referred to P. ameghinoi, a struthiolariid gastropod restricted to the early Miocene in Tierra del Fuego and Patagonia.
