The Mekong River endemic Sinomytilus harmandi possesses an internal anterior shell septum. It is thus superficially similar to the marine representatives of the, as currently defined, Septiferinae (Mytilidae) although species of the latter possess an anterior adductor muscle located between their septa and are characterised by accessory posterior adductor muscles, both of which are absent in S. harmandi. This study demonstrates that S. harmandi is monophyletic with the only other, similarly native Asian, freshwater mytiloid, Limnoperna fortunei, based on the phylogenetic tree herein presented. Asian freshwaters thus seem to have been colonised by the Mytilidae relatively recently and on two occasions from a common ancestor also associated with representatives of the Lithophaginae, as currently defined. The common presence of an anterior septum in S. harmandi and species of the Septiferinae, as currently recognised, is thus the result of convergence as is the anatomical similarity between S. harmandi and representatives of the Central European Dreissenidae (Heterodonta), which also possess an anterior shell septum.

湄公河的地方性香茅具有内部前壳隔膜。因此，它表面上类似于目前所定义的Septiferinae（Mytilidae）的海洋代表，尽管后者的物种具有位于它们的隔片之间的前内收肌，并具有附属的后内收肌特征，但两者均在S中不存在。。harmandi。这项研究表明，S. harmandi是单系与唯一的其他类似亚洲本地，淡水mytiloid，河壳菜蛤，基于此处介绍的系统树。因此，亚洲淡水似乎是最近才被Mytilidae所定殖的，并且两次是从一个共同的祖先那里定殖的，该祖先也与目前所定义的石藻科的代表有关。因此，目前认识到，在沙门氏菌中存在前隔膜和Septiferinae物种的共同存在是收敛的结果，因为沙门氏菌与中欧Dreissenidae（Heterodonta）的代表在解剖学上相似前壳隔膜。