Mussel of the

Page last updated
4 April 2024

Mussel of the Month

The April 2024 Mussel of the Month is Aculamprotula zonata. Aculamprotula is a genus of nine species distributed from South Korea through China to northern Vietnam.

Aculamprotula zonata
MCZ 167112. Ning-Kouo fou River, China (type?).

We chose Aculamprotula zonata as Mussel of the Month because 1) it is a good-looking shell, and 2) we are kind of surprised that — with all the active reclassification of freshwater mussel genera — the name Aculamprotula is still in use.

Aculamprotula Wu, Liang, Wang & Ouyang, 1999 was described to account for some species of the old Lamprotula sensu lato having triangular glochidia with hooks brooded only in the outer demibranches while other species of Lamprotula sensu stricto have unhooked glochidia brooded in all four demibranches. The ectobranchus species with hooked glochidia were moved to Aculamprotula and classified in the Unioninae, while the tetragenous species with unhooked glochidia stayed in Lamprotula in the subfamily Gonideinae (Graf & Cummings, 2021). This first-splitting of Lamprotula didn’t really take hold with the global mussel community until Pfeiffer & Graf (2013) reanalyzed the phylogenetic data published by Zhou et al. (2007).

In 2018, Huang et al. found that some of those species still left in Lamprotula actually belonged to a different family. They were transferred to the genus Gibbosula and reclassified from the Unionidae to the Margaritiferidae (Graf & Cummings, 2021).

So, there has been lots of attention paid to the species of the former Lamprotula s.l., but there is still work to do.

As we pointed out back in August 2013 when Aculamprotula fibrosa was Mussel of the Month, the type species of Lamprotula, Chama plumbea Dillwyn, 1817, is only known from a figure in Chemnitz (1795, figs. 1991-1992). Not only are we unsure where that species is from, but the shell looks a lot more like this month’s mussel, Aculamprotula zonata — which itself looks like other species of Aculamprotula. Maybe Aculamprotula should really be the one called Lamprotula, and the current Lamprotula s.s. should be called something else.

We don’t even really know if Aculamprotula zonata is a “real” species. Pfeiffer & Graf (2013) found the mtDNA sequences attributed to that species to be only 1% different from those labeled A. fibrosa and A. tientsinensis in Genbank. Whether or not Aculamprotula zonata (Heude, 1883) is a distinct evolutionary lineage/biological species, the name is pre-occupied (i.e., a junior homonym) of Unio marginalis var. zonata Hanley & Theobald, 1872 (= Trapezidens scutum) and as such is permanently invalid — without another nominal species name in synonymy to replace it.

If Aculamprotula zonata is not sunk into synonymy with another species, it needs to be given a new name — and maybe that new name will eventually be transferred back to Lamprotula!


Phylum Mollusca
Class Bivalvia
Subclass Palaeoheterodonta
Order Unionoida

Superfamily UNIONOIDEA Rafinesque, 1820
Family UNIONIDAE s.s.
Subfamily UNIONINAE s.s.
Tribe UNIONINI s.s.

Genus Aculamprotula Wu, Liang, Wang & Ouyang, 1999

Species Aculamprotula zonata (Heude, 1883)

To find out more about the story of Lamprotula and Aculamprotula, check out:
  • Graf, D.L. & K.S. Cummings. 2021. A ‘big data’ approach to global freshwater mussel diversity (Bivalvia: Unionoida), with an updated checklist of genera and species. Journal of Molluscan Studies 87(1). eyaa034.
  • Huang, X.-C., R.-W. Wu, C.-T. An, G.-L. Xie, J.-H. Su et al. 2018. Reclassification of Lamprotula rochechouartii as Margaritifera rochechouartii comb. nov. (Bivalvia: Margaritiferidae) reveal by time-calibrated multi-locus phylogenetic analyses and mitochondrial phylogenomics of Unionoida. Molecular Phylogenetics and Evolution 120: 297-306.
  • Pfeiffer, J.M. & D.L. Graf. 2013. Re-analysis confirms the polyphyly of Lamprotula Simpson, 1900 (Bivalvia: Unionidae). Journal of Molluscan Studies 79: 249-256.
  • Wu, X.-P., Y.-L. Liang, H.-Z. Wang & S. Ouyang. 1999. Morphological characters of glochidia of Unionidae and taxonomic significance. Acta Hydrobiologica Sinica 23 supplement: 139-147.
  • Zhou, C.-H., S. Ouyang, X.-P. Wu & M. Li. 2007. Phylogeny of the genus Lamprotula (Unionidae) in China based on mitochondrial DNA sequences of 16S rRNA and ND1 genes. Acta Zoologica Sinica 53(6): 1024-1030.

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