A new species of freshwater sponge, Heteromeyenia barlettai sp. nov., is proposed here based on specimens discovered in a private aquarium in São Paulo, Brazil, and most likely inadvertently collected from the Paraná Basin. The present study also presents a redescription of H. insignis on the basis of the specimen reported upon by Volkmer (1963), collected from the Atlântico Sul Hydrographic Basin. Spicule measurements (n=30) were made for comparison with other Heteromeyenia species. This is the first time that H. insignis has its complete set of spicules studied under SEM. After comparison with the redescription of the type of H. baileyi, we also find characteristics that justify the maintenance of H. insignis as a valid species. A key to species of Heteromeyenia is provided.

Corvoheteromeyenia Ezcurra de Drago, 1979 (Spongillidae) is endemic to the Neotropical Region and was erected to comprise C. australis (Bonetto & Ezcurra de Drago, 1966) and C. heterosclera (Ezcurra de Drago, 1974). However, the distinction between these species was not well-established and the type materials were not deposited in the collections as otherwise indicated in the original descriptions. Thus, in order to elucidate their specific status, this paper provides a review of the genus and proposes a neotype designation of Corvoheteromeyenia heterosclera, following Article 75 of the International Code for Zoological Nomenclature (ICZN 1999). A total of 41 specimens were analyzed and identified as belonging to Corvoheteromeyenia. Based on the literature and additional specimens, the redescription of C. australis and C. heterosclera is presented. The acanthoxea microscleres were stated as the distinctive character of both, but are present only in C. heterosclera. Corvoheteromeyenia sanidastosclera Pinheiro, Silva & Calheira, 2015, is distinct from congeners by the presence of sanidaster gemmuloscleres and also differ from C. heterosclera by the absence of acanthoxea microscleres. A key to species of Corvoheteromeyenia is provided.

Corvoheteromeyenia Ezcurra de Drago, 1979 is exclusively known from Neotropical Region with two species recorded: C. australis (Bonetto & Ezcurra de Drago, 1966) and C. heterosclera (Ezcurra de Drago, 1974). The genus is characterized by the presence of birotuled gemmuloscleres inserted radially embedded in the gemmule, by megascleres which are exclusively oxeas, occasionally sparsely microspined and pseudobirotuled microscleres present in two distinct series. A total of twelve specimens were collected in São Francisco Basin (Bahia State, Brazil) and identified as belonging to C orvoheteromeyenia. Based on this material, we record C. heterosclera for São Francisco Basin. Additionally, we describe a new species of Corvoheteromeyenia that differs from other species of genus by having gemmulosclere sanidaster. Sanidaster display an intermediate morphology between the birotule and rodlike (acanthostrongyle) spicular type. The gemmulosclere sanidaster found here could be interpreted as malformations due to environmental conditions, since malformations in gemmuloscleres had previously been observed in experimental conditions in some freshwater sponges exposed to heavy metal. However, in these conditions only 50% of gemmoscleres were malformed, and in C. sanidastosclera n. sp., 100% of gemmoscleres were sanidasters. Thus we do not believe that this morphology of spicules was the result of exposure to chemical compounds in the environment. This result reinforces the idea of Penney & Racek (1968) that the segregation of Spongillidae Gray, 1867 into two groups based on the form of gemmoscleres as proposed by Vejdovsky ( 1887) is no longer justified.

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Anheteromeyenia Schröder, 1927 (Spongillidae) was erected to comprise species of Heteromeyenia Potts, 1881 without microscleres. Until now, only four species of Anheteromeyenia are known, three from the Neotropical Region (A. cheguevarai, A. ornata and A. vitrea) and A. argyrosperma from the Nearctic Region. In the present study, we describe a new species of Anheteromeyenia from the Neotropical Region, which differs from other congeners in having only one category of megascleres, exclusively smooth oxeas. An identification key to species of Anheteromeyenia and an emended diagnosis of the genus are provided.