Data Generation

One gravid female P. streckersoni was collected from the type locality and deposited at Florida Museum (UF439535). Whole genomic DNA was extracted from fresh mantle tissue using the Qiagen PureGene Kit (Hilden, Germany) with standard protocols. High-molecular weight DNA was ensured by visualizing the isolation on a 1% agarose gel stained with GelRed nucleic acid stain (Biotium, Hayward, CA). Isolation quantity and quality was assessed using a Qubit^TM fluorometer and a NanoDrop^TM One (ThermoFisher Scientific; Waltham, MA), respectively. Before PacBio and 10X sequencing, the initial identification based on external shell morphology was confirmed by amplifying and sequencing the mt gene NADH dehydrogenase subunit 1 as described in Serb et al. (2003). A PacBio library was size selected with 10 kb cut-off following the SMRT bell construction protocol. The library was sequenced on a single-molecule real-time cell of a PacBio Sequel II using the v 2.0 chemistry. For 10X sequencing, a Chromium 10X library was constructed from high-molecular-weight DNA according to manufacturers recommended protocols. The resulting library was quantitated by qPCR and sequenced on an Illumina NovaSeq 6000 (San Diego, CA).

Total RNA was extracted from five different tissue types from the adult female: foot, gill, gonad, mantle, and stomach. In addition to total RNA extraction of adult somatic and gonadal tissue, RNA was isolated from a pool of fully developed glochidia to pick up additional transcripts expressed at the larval stage. All RNA was extracted using QIAshredder and RNeasy kits as described by the manufacturer (Qiagen). RNA quality and integrity were determined using a NanoDrop^TM and an Agilent Bioanalyzer (Santa Clara, CA), respectively. Messenger RNA (mRNA) was purified from approximately 200 ng of total RNA and a mRNA library was prepared using KAPA mRNA HyperPrep Kits (Roche; Basel, Switzerland). Indexed libraries that met appropriate cut-offs were quantified by qRT-PCR and sequenced using 100 bp paired-end sequencing on an Illumina NovaSeq 6000.