Bonnemaisonia hamifera Hariot
Also known as Trailliella intricata Batters.
Common name: Bonnemaison's Hook Weed
Description: Gametophyte plants (above right)
occurring from March-June, brownish-red, fronds feathery, with a
slightly flattened axis to 1 mm wide and 350 mm long, attached bi hooks to
Cytstoseira, Sargassum and other algae by
crozier-shaped, hook-like modified branches. Tetrasporophyte
(“Trailliella-phase”) plants (right bottom) occurring all year
round, but most obvious in October-March, brownish-red, much
branched, filamentous, in dense cotton-wool-like tufts to 25 mm
in diameter (below right .
Habitat: Introduced, probably from the western
Pacific, at the end of the last century; gametophyte first found
in Europe (Isle of Wight) in 1893.Grows on rocks and other algae,
lowest intertidal and subtidal, southern and western coasts,
rare, mostly in large sunny, mid-intertidal pools.
Tetrasporophyte first recorded in British Isles (Dorset) in
1890, epiphytic on Corallina, lower intertidal pools
and subtidal, now widely distributed on southern and western
coasts to Shetland Isles, frequent and can be abundant in
certain locations, notably where there are large, lagoon-like
lower intertidal pools.
Similar species: Gametophyte:
Bonnemaisonia asparagoides,
which lacks the crozier-shaped hooks (left) and is exclusively a
subtidal plant. Tetrasporophyte: ball-like habit is shared with
the 'Falkenbergia-phase' of Asparagopsis armata. A microscope is required to distinguish the two: the
tetrasporphyte of B. hamifera has small colourless
cells that alternate from side to side of the filamet; these are
absent in the tetrasporphyte of A. armata., which, in
addition, is several cells in width.
Key characteristics: Crozier-shaped hooks in
gametophyte (below) for secondary attachment; sesonal occurrence
on western and southern coasts from March to June.
Identification guide for selected marine non-native species (National Museum Wales). (Download free PDF, about 3.5 Mb).
Photographs © M.D. Guiry
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