A new species of toxic benthic dinoflagellate is described based on laboratory cultures isolated from two locations from Brazil, Rio de Janeiro and Bahia. The morphology was studied with SEM and LM. Cells are elliptical in right thecal view and flat. They are 37–44 μm long and 29–36 μm wide. The right thecal plate has a V shaped indentation where six platelets can be identified. The thecal surface of both thecal plates is smooth and has round or kidney shaped and uniformly distributed pores except in the central area of the cell, and a line of marginal pores. Some cells present an elongated depression on the central area of the apical part of the right thecal plate. Prorocentrum caipirignum is similar to Prorocentrum lima in its morphology, but can be differentiated by the general cell shape, being elliptical while P. lima is ovoid. In the phylogenetic trees based on ITS and LSU rDNA sequences, the P. caipirignum clade appears close to the clades of P. lima and Prorocentrum hoffmannianum. The Brazilian strains of P. caipirignum formed a clade with strains from Cuba, Hainan Island and Malaysia and it is therefore likely that this new species has a broad tropical distribution. Prorocentrum caipirignum is a toxic species that produces okadaic acid and the fast acting toxin prorocentrolide.

根据从巴西里约热内卢和巴伊亚州两个地点分离出来的实验室培养物，描述了一种新的有毒底栖鞭毛鞭毛藻物种。用SEM和LM研究了形态。在右视图中，单元格是椭圆形的，并且是平坦的。它们长37–44μm，宽29–36μm。右鞘板有一个V形凹口，可以在其中识别出六个血小板。两个孔板的孔表面均是光滑的，除了细胞的中心区域外，具有圆形或肾形的孔且分布均匀，并有一排边缘孔。一些细胞在右鞘板顶端部分的中央区域呈现出细长的凹陷。开腹原肠类似于利马原肠在形态上，但可以通过一般的细胞形状区分，椭圆形，而利马假单胞菌是卵形的。在基于ITS和LSU rDNA序列进化树中，P. caipirignum分支出现接近的分支利玛和原甲藻hoffmannianum。巴西的南美白对虾（P. caipirignum）菌株与来自古巴，海南岛和马来西亚的菌株形成了进化枝，因此这种新物种很可能具有广泛的热带分布。Caipirignum原肠原球菌是有毒物种，可产生冈田酸和速效毒素原原肠球菌。