Molecular and morphological data to facilitate future research on freshwater mussels (Bivalvia: Unionidae: Anodontinae)

This data article presents the multi-locus DNA alignments, morphometric data, and details on specimens examined to resolve the evolutionary history of Anodontoides and Strophitus, primarily generic placement and species boundaries. We sequenced 3 loci to create our molecular matrix: cytochrome c oxidase subunit I, NADH dehydrogenase subunit I, and the nuclear-encoded ribosomal internal transcribed spacer I. Aligned sequences were used in phylogenetic analyses and to identify diagnostic nucleotides for Strophitus pascagoulaensis, Strophitus radiatus, Strophitus sp. cf. pascagoulaensis, and Strophitus williamsi. Linear morphometrics (i.e. maximum height, length, and width) were also implemented to further evaluate species boundaries within Strophitus. For further details and experimental findings, please refer to the article published in Molecular Phylogenetics and Evolution (Smith et al., 2018) [1].


Value of the data
Provided sequence data and alignments can be directly utilized in future phylogenetic studies on freshwater mussels (Bivalvia: Unionidae).
All data are tied to museum vouchers, ensuring repeatability of results and facilitating further investigation of additional DNA loci and morphological characters on the same specimens used in our study.
Sequence data are available to confirm species-level identification of existing museum specimens or samples collected during future field surveys.
Molecular and morphological data provides insight on cryptic diversity within Strophitus radiatus, including diagnostic nucleotides that distinguish species within this complex.

Data
We present multi-locus sequence data for 97 individuals representing 18 species of North American freshwater mussels (Bivalvia: Unionidae) belonging to the subfamily Anodontinae. We also provide shell measurements (max length, width, and height) taken from 142 specimens used to evaluate morphological differences between Strophitus pascagoulaensis, Strophitus radiatus, Strophitus sp. cf. pascagoulaensis, and Strophitus williamsi. Our molecular matrix can be used as a tool for confirming identification of vouchered or field collected specimens. Additionally, by depositing vouchered specimens and providing full access to our DNA alignment files, morphometric measurements, and specimen collection information, our data provide a valuable resource for future research on freshwater mussel systematics, distribution, and conservation.

Molecular data collection
Our taxon sampling focused on North American freshwater mussels in the subfamily Anodontinae (Table 1). We sequenced two mitochondrial genes and one nuclear gene for phylogenetic analyses:

Molecular data processing
Chromatograms were assembled and edited in Geneious v 6.1.2 [6] and consensus sequences were aligned in Mesquite v 3.1.0 [7] using MAFFT v 7.299 [8]. The mtDNA protein coding genes COI and NDI were aligned then translated into amino acids to ensure absence of gaps and stop codons. The ITSI alignment was performed using the default parameters in MAFFT and minor adjustments were made by eye where necessary. Independent alignment files (phylip format) for COI, NDI, and ITSI are available in supplemental information (Supplemental_File_1_All_COI.phy; Supplemental_File_2_All_NDI.phy; Supplemental_File_3_All_ITSI.phy). Diagnostic nucleotides within S. pascagoulaensis, S. radiatus, S. sp. cf. pascagoulaensis, and S. williamsi were identified using MEGA6 [9]. COI, NDI, and ITSI were independently analyzed (including redundant haplotypes) and groups were determined by species: S. pascagoulaensis, S. radiatus, S. sp. cf. pascagoulaensis, and S. williamsi. We used the mitochondrial genome sequence of Cristaria plicata (GenBank Accession: KM233451) to determine nucleotide positions for COI and NDI. Base pair positions at ITSI were determined by using an alignment consisting of only A. radiatus (Supplemental_ File_4_A_radiatus_ITSI.phy). We used the sequence of our only A. radiatus from the Pearl River as a reference (Genbank accession number MG199854). Diagnostic nucleotides are provided in Table 2.

Morphological data collection
We conducted linear morphometrics of external shell dimensions for all S. pascagoulaensis, S. radiatus, S. sp. cf. pascagoulaensis, and S. williamsi specimens used in genetic analyses along with additional museum specimens from focal drainages. Three measurements were taken for morphological analyses: maximum length (anterior to posterior), height (dorsal to ventral), and width (right to left valve) to the nearest 0.01 mm using digital calipers. One person conducted all measurements, and height and width were measured at the posterior end of the hinge ligament for consistency. Raw measurements are provided in Table 3.
26 T  T  C  T  Y  ND1  27  T  T  C  T  N  ND1  39  C  C  T  C  N  ND1  40  T  T  C  T  N  ND1  63  T  T  C  T  N  ND1  90  T  T  T  C  N  ND1 120