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Asparagopsis armata Harvey
Le Jolis
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RHODOPHYCEAE
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(barbed asparagus seaweed)
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| Photo details | ||
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Whole gametophyte in tray showing the tufted branches arranged in pairs spirally around main axis as well as barbed axes. Scale: Width of plant approximately 15 cm. Location:Wembury Point, Plymouth, Devon - Photographer:Francis Bunker - Date:16/09/2001 - Identified By:Francis Bunker - Verified By: |
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| Identification Notes | ||
| The erect (gametangial) plants grow to 30 cm long as bushy plants with prominent major axes that are densely tufted and others which are naked apart from a scattering of prominent barbed spines. The densely branched axes are pyramidal in outline and composed of spirally arranged branches arising in pairs. These are shed with age giving a naked appearance to lower axes. Barbed axes usually occur in pairs and up to 10 cm in length and 2 to 4 mm wide and the spines on the barbed axes are short reflexed lateral branchlets. All axes and branchlets are corticated apart from ultimate laterals which are polysiphonous with three pericentral cells surrounding an axial cell. Plants are rose-pink, yellowish pink or white pink in colour. The tetrasporangial phase known as 'Falkenbergia' occurs as neat tangled balls of rose-pink threads 10 to 30 mm in diameter which is usually found attached to other algal species. Under a low power microscope these threads are revealed as an irregularly branched ecorticate polysiphonous axes, 40 to 50 µm in diameter with three spirally twisted pericentral cells surrounding an axial cell. The pericentral cells have associated secretory cells and under transmitted light against a dark background, they are highly refractive and seem to shine. Other characterising features: Gametangial plants are dioecious with spermatangial occurring in club-shaped swollen lateral axes up to 2 mm in length. cystocarps are flask-shaped growing to 2 mm long and with a terminal pore. Tetrasporangia occur on the 'Falkenbergia' phase being formed by the transformation of pericentral cells into ovoid tetraspores 70 x 30 µm in diameter. Dixon & Irvine, 1977 Hardy and Guiry, 2003 |
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| Confusion | ||
| Confusion The gametangial plants are fairly unmistakable but balls of thread like red algae found in the field should be checked as there is scope for confusing Falkenbergia with 'Trailliella' , the tetrasporangial phase of Bonnemaisonia hamifera. Trailliella consists of single chains of cells and is readily distinguished from the polysiphonous Falkenbergia under a microscope. |
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| Habitat | ||
| Lower intertidal pools and shallow subtidal attaching to other algae via barbed axes. Falkenbergia is mainly epiphytic but may be epilithic or even free floating. |
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| Recorded distribution | ||
| An introduced species first recorded for the British Isles in 1939 Galway. It has spread far and wide since this time along southern and western coasts being recorded from Sussex to Shetland. Gametophytes are most common in the south but have also been recorded from South Uist. |
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| Researched by | ||
| F. Bunker |
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| Synonyms | ||
| Acknowledgements | ||
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Additional Photos
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| Whole gametophyte in tray showing the tufted branches arranged in pairs spirally around main axis as well as barbed axes. Scale: Width of plant approximately 15 cm. Location:Wembury Point, Plymouth, Devon - Photographer:Francis Bunker - Date:16/09/2001 - Identified By:Francis Bunker - Verified By: | ||
| Close up to show the barbed axes of the gametophyte with its scattered reflexed lateral branchlets which are used to cling on to other algae. Scale: Length of barbed axes approximately 6 cm Location:Wembury Point, Plymouth, Devon - Photographer:Francis Bunker - Date:16/09/2001 - Identified By:Francis Bunker - Verified By: | ||
| Plant growing in the shallow subtidal viewed through the water at low tide. Note characteristic bright rose-pink colour and bush growth. Scale: Width of plant approximately 18 cm. Location:Mewstone, Plymouth, Devon - Photographer:Francis Bunker - Date:17/09/2001 - Identified By:Francis Bunker - Verified By: | ||
| Ball of Falkenbergia (the tetrasporangial phase of Asparagopsis armata). Scale: Ball width 2 cm. Location:StJustinians, Pembrokeshire - Photographer:Francis Bunker - Date:20/06/2003 - Identified By:Francis Bunker - Verified By: | ||
| Detail of Falkenbergia (the tetrasporangial phase of Asparagopsis armata) under a microscope against a black background showing the bright shine of the characteristic refractive secretory cells. Scale: Diameter of branches approximately 35 µm. Location:StJustinians, Pembrokeshire - Photographer:Francis Bunker - Date:20/06/2003 - Identified By:Francis Bunker - Verified By: | ||
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