Table S1. Collection details for samples used in this study including their Barcode of Life Database (BOLD: http://www.boldsystems.org) identifiers and GenBank accession numbers for COI-5P, ITS and psaA sequences (dash (-) indicating region not determined for that isolate).

Species / Voucher / Collection Informationa,b / Lat/Long / BOLD / Genbank COI-5P/ITS/psaA/rbcL

Chnoospora implexa J. Agardh

GWS023160 / Lord Howe I., Neds Beach, New South Wales, Australia, G.T. Kraft / -31.52/159.07 / OZSEA1600-10 / KF281116/-/-/-

Chordaria flagelliformis (O.F. Müller) C. Agardh

GWS027838 / White Horse Beach, Plymouth, MA, USA. GWS, KD, AS, MB & DM / 41.93/-70.56 / MACRO3131-11 / KF281117/-/-/-

Colpomenia bullosa (D.A. Saunders) Yamada

GWS003384 / Pachena Beach, Bamfield, BC, Canada, GWS, BC & DM / 48.79/-125.12 / MACRO138-06 / KF281118/-/-/-
GWS003394 / Pachena Beach, Bamfield, BC, Canada, GWS, BC & DM / 48.79/-125.12 / MACRO143-06 / KF281123/-/KF293727/KF281385
GWS009622 / Tahsis, Island #40 on Esperenza Inlet Chart, BC, Canada, GWS & BC / 49.81/-126.99 / MACRO1093-09 / KF281122/-/-/-
GWS009653 / Tahsis, Island #40 on Esperenza Inlet Chart, BC, Canada, GWS & BC / 49.81/-126.99 / MACRO1094-09 / KF281120/-/-/-
GWS010055 / Tahsis, Brian & ShannonÕs Channel, BC, Canada, GWS / 49.81/-126.95 / MACRO2170-10 / HM891461/-/-/-
GWS013199 / Ramsey Island (beach on NW coast), Gwaii Haanas, BC, Canada, GWS & DM / 52.57/-131.4 / MACRO1136-09 / HM890845/-/-/-
GWS013200 / Ramsey Island (beach on NW coast), Gwaii Haanas, BC, Canada, GWS & DM / 52.57/-131.4 / MACRO1137-09 / HM890846/-/-/-
GWS013201 / Ramsey Island (beach on NW coast), Gwaii Haanas, BC, Canada, GWS & DM / 52.57/-131.4 / MACRO2284-10 / HM891526/-/-/-
GWS013378 / Murchison Island Lagoon, Gwaii Haanas, BC, Canada, GWS & DM / 52.6/-131.45 / MACRO1146-09 / HM890855/-/-/-
GWS013382 / Murchison Island Lagoon, Gwaii Haanas, BC, Canada, GWS & DM / 52.6/-131.45 / MACRO1147-09 / HM890856/-/-/-
GWS013521 / Newberry Cove (east side of western inlet), Gwaii Haanas, BC, Canada, GWS & DM / 52.46/-131.45 / MACRO1151-09 / HM890860/-/-/-
GWS019746 / Alder Island, Gwaii Haanas, BC, Canada, GWS & KD / 52.44/-131.32 / MACRO2786-10 / HQ990572/-/-/-
GWS019917 / Koga Islet, Gwaii Haanas, BC, Canada, GWS & KD / 52.43/-131.38 / ABMMC13185-10 / KF281121/-/-/-
GWS020146 / Saw Reef, Gwaii Haanas, BC, Canada, GWS & KD / 52.45/-131.29 / MACRO2847-10 / HQ990617/-/-/-
GWS020383 / Hot Spring Island (east 'back' side), Gwaii Haanas, BC, Canada, GWS & KD / 52.58/-131.44 / MACRO2878-10 / HQ990632/-/-/-
GWS020491 / Hot Spring Island (north side), Gwaii Haanas, BC, Canada, GWS & KD / 52.58/-131.44 / MACRO2900-10 / HQ990643/-/-/-
GWS021646 / Soberanes Point, CA, United States of America, BC, KH & ST / 36.45/-121.93 / MACRO2635-10 / HQ990516/-/-/-
GWS021902 / Santa Cruz (Four Mile), CA, United States of America, BC, KH & ST / 36.97/-122.12 / ABMMC12098-10 / KF281119/-/-/-

Colpomenia peregrina Sauvagneau

GWS011720 / Peggys Cove, NS, Canada, GWS, DM, SH & MB / 44.49/-63.92 / MACRO2220-10 / HM891489/-/-/-
GWS011725 / Peggys Cove, NS, Canada, GWS, DM, SH & MB / 44.49/-63.92 / MACRO2223-10 / HM891490/-/-/-
GWS011879 / Paddys Head, NS, Canada, GWS & DM / 44.53/-63.95 / MACRO2240-10 / HM891504/-/-/-
GWS011881 / Paddys Head, NS, Canada, GWS & DM / 44.53/-63.95 / MACRO2242-10 / HM891506/-/-/-
GWS030143 / Niles Beach, MA, United States of America, GWS / 42.6/-70.66 / MACRO3357-12 / KF281124/-/-/-

Colpomenia sinuosa (Mertens ex Roth) Derbes & Solier

GWS016353 / Sanctuary Reef, Wynyard, Tasmania, Australia, GWS & KD / -40.99/145.77 / MACRO1827-10 / HM891305/-/-/-
GWS016408 / Stanley Breakwater, Tasmania, Australia, GWS, L. Kraft & KD / -40.77/145.31 / MACRO1838-10 / HM891310/-/-/-
GWS016523 / Stanley Breakwater, Tasmania, Australia, GWS, L. Kraft & KD / -40.77/145.31 / MACRO1860-10 / HQ990473/-/-/-
GWS018263 / Rocky Reef at Lighthouse 'Point' Piyangdo Island, Jeju, South Korea, GWS & H-G. Choi / 33.42/126.22 / MACRO2656-10 / HQ990524/-/-/-
GWS018634 / Seongsan, Jeju, South Korea, GWS & H-G. Choi / 33.46/126.94 / MACRO2578-10 / HQ990489/-/-/-
GWS024904 / Cozy Corner (Knobby Pt.), Western Australia, Australia, GWS & KD / -34.26/115.03 / PHAOZ192-10 / KF281126/-/-/-
GWS025024 / Cozy Corner (Knobby Pt.), Western Australia, Australia, GWS & KD / -34.26/115.03 / PHAOZ194-10 / KF281127/-/-/-
GWS025180 / Canal Rocks, Western Australia, Australia, GWS & KD / -33.67/115 / PHAOZ195-10 / KF281125/-/-/-

Colpomenia sp._1BC

GWS013049 / Warden Station Huxley Island, Gwaii Haanas, BC, Canada. GWS & DM / 52.43/-131.37 / MACRO2281-10 / HM891524/-/-/-

Colpomenia sp._1Jeju

GWS018382 / Hamdeok Beach, Jeju, South Korea. GWS / 33.55/126.66 / MACRO2671-10 / HQ990530/-/-/-

Colpomenia sp._1peregrina

GWS002935 / Bamfield, Seppings I., BC, Canada, HK / 48.84/-125.21 / MACRO025-06 / KF281128/-/-/-
GWS003119 / Bamfield, Scotts Bay, BC, Canada, RW / 48.83/-125.15 / MACRO1322-09 / HM890984/-/-/-
GWS003470 / Bamfield, Dixon I., BC, Canada, GWS, BC & DM / 48.85/-125.12 / MACRO1360-09 / HM891007/-/-/-

Colpomenia sp._1WA

GWS024218 / Mutton Bird I., Western Australia, Australia, GWS & KD / -35.05/117.69 / PHAOZ190-10 / KF281132/-/-/-
GWS025013 / Cozy Corner (Knobby Pt.), Western Australia, Australia, GWS & KD / -34.26/115.03 / PHAOZ193-10 / KF281130/-/-/-
GWS025528 / Blackwall Reach, Swan River, Western Australia, Australia, G. Belton / -32.02/115.78 / PHAOZ196-10 / KF281129/-/-/-
GWS025539 / Blackwall Reach, Swan River, Western Australia, Australia, G. Belton / -32.02/115.78 / PHAOZ197-10 / KF281131/-/-/-

Ectocarpus siliculosus (Dillwyn) Lyngbye

GWS030169 / Folly Cove, Gloucester, right side, MA, USA. AS / 42.69/-70.64 / MACRO3355-12 / KF281133/-/-/-

Hydroclathrus clathratus (C. Agardh) M.A. Howe

GWS018670 / Channel between Little & Big Munseom Islands, Jeju, South Korea, GWS & H-G. Choi / 33.23/126.57 / MACRO2685-10 / HQ990537/-/-/-
GWS022947 / Malabar Reef, Lord Howe I., New South Wales, Australia, GWS, KD & RW / -31.51/159.06 / PHAOZ167-10 / KF281140/-/-/-
GWS023174 / Lord Howe I., Neds Beach, New South Wales, Australia, G.T. Kraft / -31.52/159.07 / PHAOZ168-10 / KF281141/-/-/-
GWS023189 / North Head Gutters, Lord Howe, New South Wales, Australia, GWS, KD & RW / -31.52/159.04 / PHAOZ160-10 / KF281135/-/-/-
GWS023281 / North Head Gutters, Lord Howe, New South Wales, Australia, GWS, KD & RW / -31.52/159.04 / PHAOZ161-10 / KF281136/-/-/-
GWS023770 / Split Rock, Lord Howe, New South Wales, Australia, GWS & KD / -31.58/159.07 / PHAOZ162-10 / KF281134/-/-/-
GWS023844 / Split Rock, Lord Howe, New South Wales, Australia, GWS & KD / -31.58/159.07 / PHAOZ169-10 / KF281142/-/-/-
GWS024294 / Mutton Bird I., Western Australia, Australia, GWS & KD / -35.05/117.69 / PHAOZ163-10 / KF281137/-/-/-
GWS024469 / Little Beach, Western Australia, Australia, GWS & KD / -34.97/118.2 / PHAOZ164-10 / KF281138/-/-/-
GWS025181 / Canal Rocks, Western Australia, Australia, GWS & KD / -33.67/115 / PHAOZ166-10 / KF281139/-/-/-

Hydroclathrus stephanosorus Kraft

GWS022736 / Lord Howe I., Neds Beach, New South Wales, Australia. GWS & KD / -31.52/159.07 / PHAOZ159-10 / KF281143/-/-/-

Melanosiphon intestinalis (D.A. Saunders) M.J. Wynne

DM05-015 / Castalia sheltered biodiversity site, Grand Manan, NB, Canada, GWS & DM / 44.74/-66.76 / MACRO088-06 / KF281151/-/-/-
DM06-001 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO104-06 / KF281150/-/-/-
DM06-003 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO105-06 / KF281148/-/-/-
GWS000018 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS / 45.07/-66.47 / MACRO118-06 / KF281172/-/-/-
GWS002721 / Pachena Beach, Bamfield, BC, Canada, GWS / 48.79/-125.12 / MACRO021-06 / KF281171/-/-/-
GWS002928 / Bamfield, Sparlingia Pt. Bradys Beach, BC, Canada, HK & SC / 48.82/-125.16 / MACRO551-07 / KF281170/KF281395/-/-
GWS003089 / Harrington Cove exposed biodiversity site, Grand Manan, NB, Canada, GWS / 44.62/-66.86 / MACRO022-06 / KF281169/-/-/-
GWS003151 / Pachena Beach, Bamfield, BC, Canada, GWS & RW / 48.79/-125.12 / MACRO023-06 / KF293724/-/ KF293725/ KF293726
GWS003161 / Pachena Beach, Bamfield, BC, Canada, GWS & RW / 48.79/-125.12 / MACRO024-06 / KF281167/-/-/-
GWS003396 / Pachena Beach, Bamfield, BC, Canada, GWS, BC & DM / 48.79/-125.12 / MACRO1347-09 / HM890998/-/-/-
GWS003409 / Pachena Beach, Bamfield, BC, Canada, GWS, BC & DM / 48.79/-125.12 / MACRO563-07 / KF281166/-/-/-
GWS003468 / Bamfield, Dixon I., BC, Canada, GWS, BC & DM / 48.85/-125.12 / MACRO564-07 / KF281163/-/-/-
GWS003526 / Cape St. Marys, NS, Canada, GWS / 44.09/-66.2 / MACRO569-07 / KF281154/-/-/-
GWS003713 / Cottonii Creek, near Letete, NB, Canada, DM & GWS / 45.05/-66.89 / MACRO183-06 / KF281153/-/-/-
GWS003714 / Cottonii Creek, near Letete, NB, Canada, DM & GWS / 45.05/-66.89 / MACRO184-06 / KF281145/-/-/-
GWS003779 / Harrington Cove exposed biodiversity site, Grand Manan, NB, Canada, DM / 44.62/-66.86 / MACRO190-06 / KF281144/-/-/-
GWS003781 / Harrington Cove exposed biodiversity site, Grand Manan, NB, Canada, DM / 44.62/-66.86 / MACRO192-06 / KF281173/-/-/-
GWS003782 / Harrington Cove exposed biodiversity site, Grand Manan, NB, Canada, DM / 44.62/-66.86 / MACRO193-06 / KF281155/-/-/-
GWS003866 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO208-06 / KF281174/-/-/-
GWS003867 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO376-06 / KF281165/-/-/-
GWS003871 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO209-06 / KF281152/-/-/-
GWS004077 / Bamfield, Wizard I., BC, Canada, GWS, BC & DM / 48.86/-125.16 / MACRO382-06 / KF281146/-/-/-
GWS004728 / Raft Cove, Vancouver Island, BC, Canada, BC & DM / 50.59/-128.24 / MACRO598-07 / KF281147/-/-/-
GWS004823 / Ridley Island (south of coal terminal), Prince Rupert, BC, Canada, GWS, BC & DM / 54.22/-130.33 / MACRO601-07 / KF281156/-/-/-
GWS005102 / Ridley Island (north of grain terminal), Prince Rupert, BC, Canada, GWS, BC & DM / 54.22/-130.33 / MACRO609-07 / KF281157/-/-/-
GWS005688 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO628-07 / KF281158/-/KF281540/-
GWS005689 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM & GWS / 45.07/-66.47 / MACRO629-07 / KF281159/-/-/-
GWS005690 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM & GWS / 45.07/-66.47 / MACRO630-07 / KF281160/-/-/-
GWS005949 / Blacks Harbour, NB, Canada, DM & GWS / 45.04/-66.81 / MACRO737-07 / KF281162/-/-/-
GWS005950 / Blacks Harbour, NB, Canada, DM & GWS / 45.04/-66.81 / MACRO738-07 / FJ409176/-/-/-
GWS005953 / Beach Front Cottages, Seal Cove, NB, Canada, GWS / 44.65/-66.83 / MACRO739-07 / FJ409175/-/-/-
GWS006457 / Stephenson Pt., Nanaimo, BC, Canada, HK, DM, BC, KR & SH / 49.21/-123.94 / MACRO782-07 / KF281164/-/-/-
GWS006675 / Tahsis, Island #40 on Esperenza Inlet Chart, BC, Canada, BC, DM, KR & SH / 49.81/-126.99 / MACRO1482-10 / HM891091/-/-/-
GWS006802 / Tahsis, Friendly Cove, BC, Canada, DM, BC, KR & HK / 49.59/-126.62 / MACRO1492-10 / HM891099/-/-/-
GWS008268 / Bamfield, Blowhole at Bradys Beach, BC, Canada, DM, BC, KR & HK / 48.82/-125.16 / MACRO2064-10 / KF281168/-/-/-
GWS008316 / Ridley Island (south of coal terminal), Prince Rupert, BC, Canada, GWS, BC, DM & KR / 54.22/-130.33 / MACRO2067-10 / KF281161/-/-/-
GWS008875 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS & KD / 45.07/-66.47 / MACRO2117-10 / HM891428/-/-/-
GWS009221 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS / 45.07/-66.47 / MACRO2124-10 / HM891431/-/-/-
GWS009564 / Halfway Beach, near Sechelt, BC, Canada, GWS, BC, DM & KH / 49.6/-123.83 / MACRO2142-10 / HM891444/-/-/-
GWS009632 / Tahsis, Island #40 on Esperenza Inlet Chart, BC, Canada, GWS & BC / 49.81/-126.99 / MACRO1565-10 / HM891148/-/-/-
GWS010947 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO1603-10 / HM891180/-/-/-
GWS010948 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO2194-10 / HM891473/-/-/-
GWS012540 / Park at end of Honna Road, Queen Charlotte City, Haida Gwaii, BC, Canada, GWS & DM / 53.25/-132.12 / MACRO2261-10 / HM891514/-/-/-
GWS012541 / Park at end of Honna Road, Queen Charlotte City, Haida Gwaii, BC, Canada, GWS & DM / 53.25/-132.12 / MACRO1127-09 / HM890837/-/-/-
GWS012900 / Scudder Point, Burnaby Island, Gwaii Haanas, BC, Canada, GWS & DM / 52.45/-131.23 / MACRO1135-09 / HM890844/KF281396/-/-
GWS013364 / Murchison Island Lagoon, Gwaii Haanas, BC, Canada, GWS & DM / 52.6/-131.45 / MACRO1145-09 / HM890854/-/-/-
GWS019742 / Alder Island, Gwaii Haanas, BC, Canada, GWS & KD / 52.44/-131.32 / MACRO2784-10 / KF281149/-/-/-
GWS019982 / Warden Station Huxley Island, Gwaii Haanas, BC, Canada, GWS & KD / 52.43/-131.37 / MACRO2826-10 / HQ990602/-/-/-
GWS020512 / Hot Spring Island (north side), Gwaii Haanas, BC, Canada, GWS & KD / 52.58/-131.44 / MACRO2905-10 / HQ990647/-/-/-
GWS020639 / North Beach (near Naval Station), Haida Gwaii, BC, Canada, GWS & KD / 54.03/-132.05 / MACRO2922-10 / HQ990660/-/-/-
GWS022426 / 600m N/W of Roberts Creek Rivermouth, Roberts Creek, Sunshine Coast, BC, Canada, KD / 49.42/-123.66 / MACRO2966-10 / HQ990689/-/-/-
GWS022428 / 600m N/W of Roberts Creek Rivermouth, Roberts Creek, Sunshine Coast, BC, Canada, KD / 49.42/-123.66 / MACRO2968-10 / HQ990690/-/-/-

Petalonia fascia (O.F. Müller) Kuntze

CWS11-2-2 / Pleasure Beach, Waterford, CT, United States of America, C.W. Schneider / 41.31/-72.15 / MACRO3144-11 / KF281216/-/-/-
DM05-016 / Castalia sheltered biodiversity site, Grand Manan, NB, Canada, GWS & DM / 44.74/-66.76 / MACRO031-06 / KF281201/KF281406/-/-
DM06-004 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO106-06 / KF281217/KF281410/-/-
DM06-007 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO109-06 / KF281219/-/-/-
DM06-013 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO112-06 / KF281209/KF281409/-/-
DM06-020 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, DM / 45.07/-66.47 / MACRO941-08 / KF281193/KF281400/-/-
DM06-022 / St. Andrews , NB, Canada, DM / 45.07/-67.05 / MACRO115-06 / KF281208/KF281408/KF281541/KF281386
GWS000017 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS / 45.07/-66.47 / MACRO090-06 / KF281204/-/-/-
GWS002683 / Samoset Resort, ME, United States of America, GWS / 44.12/-69.08 / MACRO026-06 / KF281194/KF281401/-/-
GWS003162 / Pachena Beach, Bamfield, BC, Canada, GWS & RW / 48.79/-125.12 / MACRO027-06 / KF281195/KF281402/-/-
GWS003163 / Pachena Beach, Bamfield, BC, Canada, GWS & RW / 48.79/-125.12 / MACRO028-06 / KF281197/-/-/-
GWS003247 / Bamfield, Bradys Beach, BC, Canada, GWS / 48.82/-125.16 / MACRO029-06 / KF281198/-/-/-
GWS003392 / Pachena Beach, Bamfield, BC, Canada, GWS, BC & DM / 48.79/-125.12 / MACRO557-07 / KF281189/-/-/-
GWS003501 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS & DM / 45.07/-66.47 / MACRO030-06 / KF281200/KF281405/-/-
GWS003559 / Lepreau exposed biodiversity site, Bay of Fundy, NB, Canada, GWS & DM / 45.07/-66.47 / MACRO152-06 / KF281203/KF281407/-/-