gigartina alveata from new zealand: among the oldest and newest marine red algae in the southern...
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GIGARTINA ALVEATA FROM NEW ZEALAND:AMONG THE OLDEST AND NEWEST MARINE RED
ALGAE IN THE SOUTHERN HEMISPHERE
Max H. Hommersand & Geoffery L. Leister Department of Biology, University of North Carolina
Chapel Hill, NC, USA
&
Wendy A. NelsonNational Institute of Water and Atmospheric Research
(NIWA), Kilbirnie, Wellington, New Zealand
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Habitat of Gigartina alveata, rocky outcroppings on sandy beaches, North Island, New Zealand
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Gigartina alveata, with up to 12 dichotomies, withstands desiccation well
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Gigartina alveata: concavo-convex shape of the thallusshowing the canaliculae and curved tips
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Joseph Banks, 1774
Sir Joseph Banks (Barron)
Fucus alveatus Turn.Lectotype: BM,Ex. Herb. Banks
Fucus alveatus Turner1819, pl. 239a (1/2 size)Coast of New Zealand
Gigartina alveata (Turn.) J. Ag. Herb. Agardh (LD 23721) (Sent by Harvey from TCD)
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North New Zealand Motuarohia Island (‘Motuaro’)
CaptainCook
Mercury Bay
Mercury Bay
Bay of Islands
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Phyllophoraceae
'alveata'
Gigartina / Rhodoglossum
Chondracanthus
OstiophyllumSarcothalia
'skottsbergii'
Iridaea / "Sarcothalia"
Mazzaella
Chondrus
100
76
52
84
100
81
99 100
10076
94
1000 Bootstrap replicates
L = 2146 Cl = 0.341 RI = 0.693
L = 2164 CI = 0.341 RI = 0.693
20 changes
Phylogeny of theGigartinaceae
rbcL tree
subgenus Eogigartina
subgenus Chondracanthus
Mastocarpus stellatusPhyllophora crispa
D.W. Freshwater(In: Hommersand et al.1994, 1999)
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View from concave side(cystocarps along margin and on convex side)
Gigartina alveata - cystocarpic
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Tetrasporangia in series derived from primary cortical filaments
Tetrasporangial sori (arrows)
(Lindauer 1949)
Gigartina alveata (tetrasporangia)
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Gigartina alveata Tip of a male plant
Cross section showing spermatangial clusters (arrows)
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Carpogonial branch before Carpogonial branch after fertilization presumed fertilization
(= Aux cell?)
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Gigartinaceae
Cystocarps showingtypes of internal
pericarps
Green = secondary filaments
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Auxiliary cell
Cystocarp envelope (arrows) forming from cortical filaments around the functional auxiliary cell
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cortex
medulla
Auxiliary cell
Cortical cells form rosettes of short-celled filamentsMedullary cells (arrowheads) undergo intercalary cell divisions
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cortex
medulla
gonimoblasts
The auxiliary cell has produced gonimoblastsThe modified medullary cells have formed rosettes
developing envelope
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Gonimoblastfilaments (g)elongate and ramify through
the medulla
g
Older stage with amixture of gonimoblastfilaments, medullary
cells and carpo-sporangia
Carposporangiaappear to arisefrom medullary
cells
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Young gonimoblasts surrounded by developing envelope with ostiole
ostiole
gonimoblasts
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Mature cystocarp with an auxiliary cell (ac), gonimoblast filaments, medullary cells, carposporangia and a spinose envelope with an ostiole
ostiole
ac
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CONCLUSION
1. Our observations call for establishment of a new genus and combination: Psilophycus alveatus (Turner) W.A. Nelson, Leister & Hommersand.
WHAT ELSE WOULD BE IMPORTANT TO KNOW?
2. The behavior of the nuclei in the development of the gonimoblast filaments and the possible role of the modified medullary cells in the formation of the carposporangia should be investigated.
3. The life history needs to be studied: To what extent is the life cycle sexual, apomictic or clonal by vegetative propagation?
4. Etc., etc.