Pseudothecadinium campbellii, a phototrophic, thecate, marine benthic species, has been found in the Sea of Japan, Russia. The morphological description of the species has been emended, and the thecal tabulation pattern is now APC 4′ 2a 4″ 6c 6 s 5‴ 1⁗. Our study indicates that P. campbellii is related to Thecadinium kofoidii and Thecadiniopsis tasmanica, based on a unique morphological feature: incomplete precingular plate series. Previously, molecular data was not available for the taxa, and thus the phylogenetic position of P. campbellii within the Dinophyceae remained obscure. In this study, analyses of the rRNA gene sequences (partial 18S and 28S) revealed that unexpectedly, P. campbellii is most closely related to Halostylodinium arenarium. It formed a common clade with the Thecadinium sensu stricto clade comprising T. kofoidii and T. pseudokofoidii. This clade was placed within the order Gonyaulacales. However, almost no similarity in morphology was found between the two genetically closest species. In addition, they have different lifestyles: unlike P. campbellii, the nonmotile stage is dominant in the life cycle of H. arenarium. It has been shown that other genetically similar species (T. kofoidii, T. pseudokofoidii, T. yashimaense) exhibited some morphological features that unite them with gonyaulacoids.

在日本海，俄罗斯海中发现了一种伪营养的坎贝假单胞菌属的海洋底栖物种。该物种的形态描述得到了改进，现在的标度制表模式为APC 4'2a 4” 6c 6 s 5⁗1‴。我们的研究表明，P.坎有关Thecadinium kofoidii和Thecadiniopsis tasmanica，基于一个独特的形态特征：不完全precingular板系列。以前，该分类单元的分子数据不可用，因此，坎贝氏杆菌在恐龙科中的系统发育位置仍然不清楚。在这项研究中，对rRNA基因序列（部分18S和28S）的分析表明，意外地，坎氏疟原虫与Halostylodinium arenarium关系最密切。它与包括T. kofoidii和T. pseudokofoidii的严格的Thecadinium sensu严格进化枝形成普通进化枝。这个进化枝被放置在Gonyaulacales的命令中。然而，在两个遗传上最接近的物种之间几乎没有形态上的相似性。此外，他们有不同的生活方式：与P.坎，在无动力的阶段是在生命周期的主导H.蓬。已经显示的是其它基因相似物种（T. kofoidii，T. pseudokofoidii，T. yashimaense）表现出一些形态特征，使它们与淋腺类胶体结合在一起。