Lanceolaria is an easily recognizable and widespread genus, distributed from eastern Russia south to Vietnam. It is an interesting genus to us as a representative of the subfamily Unioninae – the most easily recognized subfamily of the Unionidae.
Bouchet & Rorcoi (2010) recently took the bull by the horns and established seven subfamilies for the Unionidae, the most species-rich family of freshwater mussels: Unioninae, Ambleminae, Gonideinae, Rectidentinae, Parreysiinae, Coelaturinae, and Modellnaiinae. This was definitely an improvement over the two-subfamily-and-many-many-incertae-sedis-genera system we had punted with earlier (Graf & Cummings, 2006, 2007). Since 2010, Whelan et al. (2011) refined this new system somewhat by revising the Coelaturini as a tribe within the Parreysiinae, and this taxonomy is definitely something we can work with.
While the new classification established the subfamilies, the actual generic constituents of those taxa was indicated only by the synonymy of family-group level names. As far as we know, ours is the only list assigning all genera to these new subfamilies, although some are certainly guesses or placed by process of elimination. The challenge of these new subfamilies is that we really don’t have a good handle on the characters that diagnose them. We have had to rely on geography (Ambleminae), molecular characters (Parreysiinae), monotypy (Modellnaiinae), and intuition (Gonideinae, Rectidentinae).
But, among the subfamilies, the Unioninae is a shining star of recognizability. Members of this clade are diagnosed by hooked-type glochidia, and they consistently present an ectobranchous marsupium (i.e., they brood in the outer demibranchs). The placement of Lanceolaria among the Unioninae has also been supported by its frequent inclusion in phylogenetic analyses (Huang et al., 2002; Zhou et al., 2007; Ouyang et al., 2011).
We have optimism for the new classification of the Unionidae. What we are still waiting on is confidence. |
