Taxonomic revision of the Devonian chitinozoan Ramochitina boliviensis Grahn, 2002, a junior synonym of Ramochitina ramosi Sommer and van Boekel, 1964

Abstract

A taxonomic revision of Middle Devonian chitinozoans, identified as Ramochitina boliviensis Grahn, 2002, from the Tacobo TCB X-1001 and Ramos R-1011 boreholes in the Los Monos Formation of the Tarija Basin (South Bolivia and northwestern Argentina), has been conducted. Given the morphological similarities between R. boliviensis and Ramochitina ramosi (Sommer & van Boekel, 1964), an extensive literature review and detailed morphometric analysis were performed. The results indicate that both species range from the late Emsian to the middle Givetian and are restricted to Western Gondwana. Statistical analysis revealed that the overall measurements of R. boliviensis fall within the morphometric distribution of R. ramosi, with one spongy thick spine from the holotype of R. boliviensis considered a possible teratological form. Given the overlapping stratigraphic ranges, occurrences, and morphometrics, it is proposed that the morphological differences between R. boliviensis and R. ramosi represent intraspecific variability within R. ramosi or teratological forms of this species. The emendation of the species includes simple and branched spines within the same specimen. Consequently, Ramochitina boliviensis should be considered a junior synonym of Ramochitina ramosi.