Research Assistant Program

Scientific Project

 The identity of Hoplisoma flaveolum and how this affects the systematics of Brochis

Dr. Luiz F. C. Tencatt

 Hoplisoma flaveolum (Ihering, 1911) is a small-sized Corydoradinae catfish described from tributaries of the rio Piracicaba, upper rio Paraná basin, in São Paulo State, Brazil. Since its description, small specimens with several small, dark spots all over the body from the rio Piracicaba are being attributed to H. flaveolum. Even though it seems like an obvious association, the analysis of the holotype of H. flaveolum points in another direction. The holotype presents the following morphological features: (I) ventral laminar expansion of the infraorbital 1 well developed, (II) infraorbital 2 wide, with triangular processes on its midposterior margin and conspicuous roughly triangular projection on its posterodorsal margin, (III) absence of contact between the posterior process of the parieto-supraoccipital and the nuchal plate, (IV) dorsal spine short and with posterior margin lacking serrations, and (V) posterior margin of the pectoral spine laminar, mostly smooth, with only a few poorly-developed serrations on its proximal portion.

The are at least two important implications arising from this discovery. First, the aforementioned specimens frequently captured in the rio Piracicaba basin do not exhibit such features. Second, there is a more recently species sharing all of the aforementioned features, Brochis difluviatilis (Britto & Castro, 2002). Brochis difluviatilis is a very peculiar species of Brochis, as it does not present the typical morphological pattern of the genus. As its sister species (and sharing its general morphology and color pattern), we also have Brochis garbei (Ihering, 1911). The recent revalidation of Brochis raised important questionings among our research group, such as: should Brochis be considered in a broad approach (including all of its subclades in a single genus)? Or in a stricter approach (placing each subclade in different genera)? Before any decision-making, it is essential that we first solve the identity of H. flaveolum and B. difluviatilis, and only then decide the best course of action.

Therefore, the aim of this project is to provide a comprehensive taxonomy review of both H. flaveolum and B. difluviatilis, based on morphological and molecular data. To do so, we need resources to gather as much material/information as we can. Additionally, we also need resources to process all of this material/information. The plan is to make a scientific expedition to the upper rio Paraná basin in order to collect specimens from their type localities and also visit museums/collections in order to gather more specimens and to prepare better photographic material of the type specimens. For the travels/expedition’s expenses, we estimate around 2.000 pounds, and for renew our photographic material (macro lens) plus collecting tools (cast nets, seine nets, buckets, etc.) an average of 1.000 pounds.