Priority = time, but place matters

The rule is simple. He who publishes a taxon first has priority with his name (provided that the ICZN-rules are followed). This rule can effect the choice of the outlet. There is a vast array of journals, often with their own target groups, but only a limited number of them will publish taxonomic works. One could expect a ‘natural selection’ towards the more well-known, international journals. Especially since many scientists are longing to have their papers published in ISI-rated journals (the dream of many taxonomists is to have once a paper in Nature or Science, few are lucky enough to reach their goal). However, there are always exceptions for whatever reasons. But even then the importance of the outlet can matter. An (non-Neotropical) example may illustrate this.
Ataba2007

In 2006 Christian Altaba described a fossil helicodontid from Mallorca as Darderia bellverica, and submitted his paper to a journal which was published early 2007. The same taxon has been described as Oestophora cuerdai by Quintana, Vicens & Pons, 2007. The result was a discussion about the publication date*, largely due to the fact that both journals were published later than the year in which the volume was due. This highlights the role of the editor and his sense for precision, viz. to clearly and correctly state the actual date of publication on the cover. High-standards journals are then clearly in advantage. But ultimately it is the author who chooses in which journal he wants to publish his paper. Especially when describing new taxa, this example tells us how the place can matter.

References:
Altaba, C.R., 2006 [2007]. A new land snail from the Quartenary of Mallora (Belearic Islands, Western Medeiterranean): Darderia bellverica n.gen n.sp. (Gastropoda, Pulmonata, Helicondontidae). - Anim. Biod. Cons. 29: 195-200.
*
Altaba, C.R., 2007. Reply to Quintana et al. (2007): Darderia bellverica Altaba, 2007 is the correct name for the Mallorcan fossil helicondontid. - Spira 2: 191-196.
Quintana, J., Vicens, D. & Pons, G.X., 2006 [2007]. A new species of the genus Oestrophora Hesse, 1907 (Gastropoda: Pulmonata: Trissexodontidae) from the Upper Pleistocene of Mallorca (Belearic Islands, Western Mediterranean). - Bol. Soc. Hist. Nat. Bal. 49: 51-58.
*
Quintana, J., Pons, G.X. & Vicens, D., 2007. Algunas anotaciones criticas sobre Oestrophora cuerdai Quintana, Vicens et Pons, 2006 (Mollusca: Pulmonata: Helicodontidae). - Spira 2: 157-162.

Update:
Christian Altaba (pers. comm.) suggested that
ZooBank could solve this kind of situations once it is fully operational. I think he is right.