Table 1.

Information of all specimens used in this study. Photosymbiotic taxa are bolded. Abbreviations are as the following. UCM Museum of Natural History, University of Colorado Boulder, FMNH the Field Museum, WA Western Australian Museum, UMMZ Museum of Zoology, University of Michigan, MCZ Museum of Comparative Zoology, Harvard University, SRA NCBI Sequence Read Archive

Species	Locality	Voucher	Tissue	SRA	Contigs	N50	Source
Fulvia lineonotata	Guam	UCM48073	Mantle	SRR11252446	243,326	688	De novo
Americardia media	USA	FMNH 315293	Muscle	SRR11252445	182,732	527	De novo
Corculum cardissa	Australia	WA263	Mantle	SRR11252439	371,151	483	De novo
Fragum fragum	Guam	UCM48094	Mantle	SRR11252438	608,501	460	De novo
Fragum mundum	Australia	WA265	Whole	SRR11252437	333,455	492	De novo
Fragum scruposum	Guam	UCM48090	Mantle	SRR11252436	376,388	508	De novo
Fragum unedo	Australia	BivAToL-75 (FMNH)	Muscle	SRR8217860	121,185	393	[26]
Lunulicardiasp.	Australia	FMNH 317975	Muscle	SRR8217812	244,397	404	[26]
Microfragum festivum	Australia	WA261	Whole	SRR11252435	174,309	548	De novo
Laevicardium serratum	USA	BivAtoL-57 (FMNH)	Muscle	SRR8217867	162,615	536	[26]
Laevicardium sp. Curaçao	Curaçao	BivAtoL-456 (FMNH)	Muscle	SRR11252434	196,243	472	De novo
Acanthocardia tuberculata	Italy	UMMZ 39326	Mantle	SRR11252433	241,101	554	De novo
Cerastoderma edule	England	BivAToL-21 (FMNH)	Muscle	SRR8217858	120,092	594	[26]
Vasticardium pectiniforme	Japan	UCM48108	Muscle	SRR8217813	144,372	485	[26]
Vasticardium compunctum	Japan	UCM48123	Muscle	SRR11252432	134,451	478	De novo
Dallocardia muricata	USA	BivAtoL-454 (FMNH)	Muscle	NA	177,010	368	De novo
Papyridea lata	Curaçao	MCZ 383047	Muscle	SRR8217866	267,529	345	[26]
Trachycardium egmontianum	USA	FMNH 344567	Muscle	NA	186,788	350	De novo
Hippopussp.	Japan	UCM48120	Mantle	SRR11252444	187,464	406	De novo
Tridacna crocea	Cultured	UMMZ 304399	Mantle	SRR11252443	251,344	1092	De novo
Tridacna derasa	Cultured	UMMZ 304400	Mantle	SRR11252442	245,928	1056	De novo
Tridacna maxima2	Cultured	UMMZ 304398	Mantle	SRR12252441	298,624	956	De novo
Tridacna maxima1	Cultured	NA	Muscle	SRR8217859	176,478	527	[26]
Tridacna squamosa	Cultured	UMMZ 304401	Mantle	SRR12252440	245,781	1111	De novo
Outgroup
Cardites antiquatus	Spain	MCZ 379178	Muscle	SRR1560458	113,906	567	De novo
Chama macerophylla	Panama	MCZ 381299	Muscle	SRR8217830	165,533	686	De novo
Corbicula fluminea	USA	BivAToL-242 (FMNH)	Muscle	SRR1559272	176,007	763	[24]
Galeomma turtoni	Spain	MCZ 378975	Muscle	SRR1560274	92,358	548	[24]
Hiatella arctica	UK	BivAToL-195 (FMNH)	Muscle	SRR1560281	73,557	576	[24]
Lyonsia floridana	USA	BivAToL-248 (FMNH)	Muscle	SRR1560310	92,076	838	[24]
Mya arenaria	NA	MCZ 381391	Muscle	SRR1560361	98,870	873	[24]
Neotrigonia margaritacea	Australia	MCZ 379092	Muscle	SRR1560432	162,657	549	[24]
Calyptogena gnifica	USA	NA	Mantle	SRR8217831	42,445	399	[26]