Two non-indigenous species of Hippopodina (Bryozoa: Cheilostomatida) in the southwestern Atlantic: taxonomy and biogeography

Abstract

ABSTRACT The taxonomic reassessment of Brazilian material previously assigned to Hippopodina feegeensis (Busk, 1884) revealed the occurrence of two distinct species in the southwestern Atlantic: H. feegeensis and Hippopodina similis Souto & Reverter-Gil, 2024. Specimens from artificial and natural substrates along the Brazilian coast were examined using stereomicroscopy and scanning electron microscopy (SEM), and compared with historical specimens from Ernst Marcus’ collection. The species are distinguishable by characters of the frontal pseudopores, primary orifice, avicularia, ooecium, and ancestrular complex. Hippopodina feegeensis appears restricted to artificial structures in northeastern Brazil, whereas H. similis occurs mainly in southeastern and southern Brazil on both artificial and natural substrates. The recurrent association of both species with harbors and other man-made structures, combined with their disjunct Atlantic distribution, supports their likely involvement in maritime-mediated bioinvasion processes. The clarification of species boundaries within the H. feegeensis complex refines the biogeographical understanding of the genus in the southwestern Atlantic and underscores the importance of accurate taxonomy for detecting and monitoring non-indigenous bryozoans along the Brazilian coast.