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Marine mesograzers use macroalgae as food and habitat and may have strong top‐down effects on plants and macroalgae. Sympatric mesograzer species often differ regarding host use and feeding behavior, which may lead to distinct impacts by these consumers on primary producers. The amphipods Hyale niger and Ampithoe marcuzzii are mesograzers abundant that co‐occur in Brazilian waters and, although they use several macroalgae as habitat, it is unknown how much the food value of these hosts explains the host use pattern by the two mesograzers. Herein, we investigated the abundance and feeding behavior of the sympatric amphipods H. niger and A. marcuzzii. For that, their abundance on the macroalgal hosts Sargassum filipendula, Padina gymnospora, and Dichotomaria marginata was evaluated seasonally in a rocky shore at Fortaleza Beach, state of São Paulo, Brazil. Also, multiple‐choice and no‐choice feeding experiments were carried out at laboratory to evaluate the feeding behavior of these mesograzers. The abundance of H. niger was similar among the three macroalgal hosts (except during winter), while A. marcuzzii was more abundant on Dichotomaria and Padina than Sargassum in all seasons. Moreover, H. niger consumed more Padina than Dichotomaria and Sargassum in both feeding experiments. In turn, A. marcuzzii preferred to feed on Padina when it had a choice and consumed the three macroalgal hosts at similar levels in the no‐choice feeding experiment. Overall, H. niger and A. marcuzzii differ from each other regarding their feeding behavior and host use pattern. In particular, the food value of macroalgae seems to partially explain the host use by A. marcuzzi, but not by H. niger. The differences between H. niger and A. marcuzzii may result in varying impacts on primary producers.

Hernáez et al. (2020) described a new species of ghost shrimp, Neocallichirus pinheiroi, from northeastern coast of Brazil, Western Atlantic. Although the description and figures presented by Hernáez et al. (2020) fully characterize the new species, the journal issue in which the description appeared was published online only, and the article in which N. pinheiroi appeared did not include a ZooBank registration number (LISD), required for validation of new names in electronic-only publications [vide Art. 8.5.3 of the amended Code of the International Commission on Zoological Nomenclature (ICZN, 1999, 2012)]. As result, the name Neocallichirus pinheiroi Hernáez, Windsor, Paula & Santana, 2020, is not available according the International Code of Zoological Nomenclature (ICZN, 1999, 2012). Therefore, the present note serves to validate the name Neocallichirus pinheiroi by fulfilling the ICZN conditions for nomenclatural availability.