Transcript PSA PowerPoint File - Biology Department

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. Nelson
National Institute of Water and Atmospheric Research
(NIWA), Kilbirnie, Wellington, New Zealand
Habitat of Gigartina alveata, rocky outcroppings on
sandy beaches, North Island, New Zealand
Gigartina alveata, with up to 12 dichotomies,
withstands desiccation well
Gigartina alveata: concavo-convex shape of the thallus
showing the canaliculae and curved tips
Joseph Banks, 1774
Fucus alveatus Turner
1819, pl. 239a (1/2 size)
Coast of New Zealand
Fucus alveatus Turn.
Lectotype: BM,
Gigartina alveata (Turn.) J. Ag.
Ex. Herb. Banks
Herb. Agardh (LD 23721)
(Sent by Harvey from TCD)
Sir Joseph Banks (Barron)
Captain
Cook
Mercury Bay
Bay of Islands
Mercury Bay
North New Zealand
Motuarohia Island (‘Motuaro’)
Chondrus
LL == 2164
2146
CI
Cl == 0.341
0.341
RI
RI == 0.693
0.693
94
Mazzaella
76
20 changes
Phylogeny of the
Gigartinaceae
99
100
100
81
rbcL tree
'skottsbergii'
Sarcothalia
Ostiophyllum
subgenus Chondracanthus
76
D.W. Freshwater
Iridaea /
"Sarcothalia"
100
(In: Hommersand et al.
1994, 1999)
Chondracanthus
subgenus Eogigartina
100
52
84
Gigartina /
Rhodoglossum
'alveata'
Phyllophoraceae Mastocarpus stellatus
Phyllophora crispa
1000 Bootstrap replicates
Gigartina alveata - cystocarpic
View from concave side
(cystocarps along margin
and on convex side)
Tetrasporangial
sori (arrows)
Gigartina alveata
(tetrasporangia)
(Lindauer 1949)
Tetrasporangia in series derived from primary cortical filaments
Gigartina alveata
Tip of a male plant
Cross section showing spermatangial clusters (arrows)
(= Aux cell?)
Carpogonial branch before
fertilization
Carpogonial branch after
presumed fertilization
Gigartinaceae
Cystocarps showing
types of internal
pericarps
Green
= secondary filaments
Auxiliary cell
Cystocarp envelope (arrows) forming from cortical
filaments around the functional auxiliary cell
c
o
r
t
e
x
Auxiliary cell
m
e
d
u
l
l
a
Cortical cells form rosettes of short-celled filaments
Medullary cells (arrowheads) undergo intercalary cell divisions
developing
envelope
c
o
r
t
e
x
m
e
d
u
l
l
a
gonimoblasts
The auxiliary cell has produced gonimoblasts
The modified medullary cells have formed rosettes
g
Gonimoblast
filaments (g)
elongate and
ramify through
the medulla
Older stage with a
Carposporangia
mixture of gonimoblast appear to arise
filaments, medullary
from medullary
cells and carpocells
sporangia
ostiole
gonimoblasts
Young gonimoblasts surrounded by developing
envelope with ostiole
ostiole
ac
Mature cystocarp with an auxiliary cell (ac), gonimoblast
filaments, medullary cells, carposporangia and a spinose
envelope with an ostiole
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.