GIGARTINA ALVEATA FROM NEW ZEALAND:

1
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
2
Habitat of Gigartina alveata, rocky outcroppings
on sandy beaches, North Island, New
Zealand
3
Gigartina alveata, with up to 12 dichotomies,
withstands desiccation well
4
Gigartina alveata concavo-convex shape of the
thallus showing the canaliculae and curved tips
5
Fucus alveatus Turner 1819, pl. 239a (1/2
size) Coast of New Zealand
Joseph Banks, 1774
Fucus alveatus Turn. Lectotype BM, Ex. Herb.
Banks
Gigartina alveata (Turn.) J. Ag. Herb. Agardh
(LD 23721) (Sent by Harvey from TCD)
Sir Joseph Banks (Barron)
6
Captain Cook
Mercury Bay
Bay of Islands
Mercury Bay
North New Zealand
Motuarohia Island (Motuaro)
7
Phylogeny of the Gigartinaceae
rbcL tree
subgenus Chondracanthus
D.W. Freshwater (In Hommersand et al. 1994, 1999)
subgenus Eogigartina
Mastocarpus stellatus Phyllophora crispa
8
Gigartina alveata - cystocarpic
View from concave side (cystocarps along
margin and on convex side)
9
Tetrasporangial sori (arrows) (Lindauer 1949)
Gigartina alveata (tetrasporangia)
Tetrasporangia in series derived from primary
cortical filaments
10
Gigartina alveata Tip of a male plant
Cross section showing spermatangial clusters
(arrows)
11
( Aux cell?)
Carpogonial branch before Carpogonial branch
after fertilization
presumed fertilization
12
Gigartinaceae Cystocarps showing types of
internal pericarps Green secondary filaments
13
Auxiliary cell
Cystocarp envelope (arrows) forming from cortical
filaments around the functional auxiliary
cell
14
cortex
medulla
Auxiliary cell
Cortical cells form rosettes of short-celled
filaments Medullary cells (arrowheads) undergo
intercalary cell divisions
15
developing envelope
cortex
medulla
gonimoblasts
The auxiliary cell has produced gonimoblasts The
modified medullary cells have formed rosettes
16
g
Gonimoblast filaments (g) elongate and ramify
through the medulla
Older stage with a mixture of gonimoblast filament
s, medullary cells and carpo- sporangia
Carposporangia appear to arise from
medullary cells
17
ostiole
gonimoblasts
Young gonimoblasts surrounded by developing
envelope with ostiole
18
ostiole
ac
Mature cystocarp with an auxiliary cell (ac),
gonimoblast filaments, medullary cells,
carposporangia and a spinose
envelope with an ostiole
19
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.